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ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
Parsed test spec with 3 sessions
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
starting permutation: s2snitch s1b s1s s2detach s1cancel s1insert s1c
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2snitch: insert into d4_pid select pg_backend_pid();
step s1b: begin;
step s1s: select * from d4_primary;
a
-
1
2
(2 rows)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2detach: alter table d4_primary detach partition d4_primary1 concurrently; <waiting ...>
step s1cancel: select pg_cancel_backend(pid) from d4_pid; <waiting ...>
step s2detach: <... completed>
ERROR: canceling statement due to user request
step s1cancel: <... completed>
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
pg_cancel_backend
-----------------
t
(1 row)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s1insert: insert into d4_fk values (1);
ERROR: insert or update on table "d4_fk" violates foreign key constraint "d4_fk_a_fkey"
step s1c: commit;
starting permutation: s2snitch s1b s1s s2detach s1insert s1c
step s2snitch: insert into d4_pid select pg_backend_pid();
step s1b: begin;
step s1s: select * from d4_primary;
a
-
1
2
(2 rows)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2detach: alter table d4_primary detach partition d4_primary1 concurrently; <waiting ...>
step s1insert: insert into d4_fk values (1);
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
ERROR: insert or update on table "d4_fk" violates foreign key constraint "d4_fk_a_fkey"
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2detach: <... completed>
step s1c: commit;
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
starting permutation: s2snitch s1brr s1s s2detach s1cancel s1insert s1c
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2snitch: insert into d4_pid select pg_backend_pid();
step s1brr: begin isolation level repeatable read;
step s1s: select * from d4_primary;
a
-
1
2
(2 rows)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2detach: alter table d4_primary detach partition d4_primary1 concurrently; <waiting ...>
step s1cancel: select pg_cancel_backend(pid) from d4_pid; <waiting ...>
step s2detach: <... completed>
ERROR: canceling statement due to user request
step s1cancel: <... completed>
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
pg_cancel_backend
-----------------
t
(1 row)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s1insert: insert into d4_fk values (1);
ERROR: insert or update on table "d4_fk" violates foreign key constraint "d4_fk_a_fkey"
step s1c: commit;
starting permutation: s2snitch s1brr s1s s2detach s1insert s1c
step s2snitch: insert into d4_pid select pg_backend_pid();
step s1brr: begin isolation level repeatable read;
step s1s: select * from d4_primary;
a
-
1
2
(2 rows)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2detach: alter table d4_primary detach partition d4_primary1 concurrently; <waiting ...>
step s1insert: insert into d4_fk values (1);
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
ERROR: insert or update on table "d4_fk" violates foreign key constraint "d4_fk_a_fkey"
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2detach: <... completed>
step s1c: commit;
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
starting permutation: s2snitch s1b s1declare s2detach s1cancel s1fetchall s1insert s1c
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2snitch: insert into d4_pid select pg_backend_pid();
step s1b: begin;
step s1declare: declare f cursor for select * from d4_primary;
step s2detach: alter table d4_primary detach partition d4_primary1 concurrently; <waiting ...>
step s1cancel: select pg_cancel_backend(pid) from d4_pid; <waiting ...>
step s2detach: <... completed>
ERROR: canceling statement due to user request
step s1cancel: <... completed>
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
pg_cancel_backend
-----------------
t
(1 row)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s1fetchall: fetch all from f;
a
-
1
2
(2 rows)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s1insert: insert into d4_fk values (1);
ERROR: insert or update on table "d4_fk" violates foreign key constraint "d4_fk_a_fkey"
step s1c: commit;
starting permutation: s2snitch s1b s1declare s2detach s1fetchall s1insert s1c
step s2snitch: insert into d4_pid select pg_backend_pid();
step s1b: begin;
step s1declare: declare f cursor for select * from d4_primary;
step s2detach: alter table d4_primary detach partition d4_primary1 concurrently; <waiting ...>
step s1fetchall: fetch all from f;
a
-
1
2
(2 rows)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s1insert: insert into d4_fk values (1);
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
ERROR: insert or update on table "d4_fk" violates foreign key constraint "d4_fk_a_fkey"
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2detach: <... completed>
step s1c: commit;
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
starting permutation: s2snitch s1b s1declare s2detach s1cancel s1svpt s1insert s1rollback s1fetchall s1c
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2snitch: insert into d4_pid select pg_backend_pid();
step s1b: begin;
step s1declare: declare f cursor for select * from d4_primary;
step s2detach: alter table d4_primary detach partition d4_primary1 concurrently; <waiting ...>
step s1cancel: select pg_cancel_backend(pid) from d4_pid; <waiting ...>
step s2detach: <... completed>
ERROR: canceling statement due to user request
step s1cancel: <... completed>
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
pg_cancel_backend
-----------------
t
(1 row)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s1svpt: savepoint f;
step s1insert: insert into d4_fk values (1);
ERROR: insert or update on table "d4_fk" violates foreign key constraint "d4_fk_a_fkey"
step s1rollback: rollback to f;
step s1fetchall: fetch all from f;
a
-
1
2
(2 rows)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s1c: commit;
starting permutation: s2snitch s1b s1declare s2detach s1svpt s1insert s1rollback s1fetchall s1c
step s2snitch: insert into d4_pid select pg_backend_pid();
step s1b: begin;
step s1declare: declare f cursor for select * from d4_primary;
step s2detach: alter table d4_primary detach partition d4_primary1 concurrently; <waiting ...>
step s1svpt: savepoint f;
step s1insert: insert into d4_fk values (1);
ERROR: insert or update on table "d4_fk" violates foreign key constraint "d4_fk_a_fkey"
step s1rollback: rollback to f;
step s1fetchall: fetch all from f;
a
-
1
2
(2 rows)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s1c: commit;
step s2detach: <... completed>
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
starting permutation: s2snitch s1b s2detach s1declare s1cancel s1fetchall s1insert s1c
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2snitch: insert into d4_pid select pg_backend_pid();
step s1b: begin;
step s2detach: alter table d4_primary detach partition d4_primary1 concurrently;
step s1declare: declare f cursor for select * from d4_primary;
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
step s1cancel: select pg_cancel_backend(pid) from d4_pid;
pg_cancel_backend
-----------------
t
(1 row)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s1fetchall: fetch all from f;
a
-
2
(1 row)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s1insert: insert into d4_fk values (1);
ERROR: insert or update on table "d4_fk" violates foreign key constraint "d4_fk_a_fkey"
step s1c: commit;
starting permutation: s2snitch s1b s2detach s1declare s1fetchall s1insert s1c
step s2snitch: insert into d4_pid select pg_backend_pid();
step s1b: begin;
step s2detach: alter table d4_primary detach partition d4_primary1 concurrently;
step s1declare: declare f cursor for select * from d4_primary;
step s1fetchall: fetch all from f;
a
-
2
(1 row)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s1insert: insert into d4_fk values (1);
ERROR: insert or update on table "d4_fk" violates foreign key constraint "d4_fk_a_fkey"
step s1c: commit;
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
starting permutation: s2snitch s1b s2detach s1declare s1cancel s1svpt s1insert s1rollback s1fetchall s1c
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2snitch: insert into d4_pid select pg_backend_pid();
step s1b: begin;
step s2detach: alter table d4_primary detach partition d4_primary1 concurrently;
step s1declare: declare f cursor for select * from d4_primary;
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
step s1cancel: select pg_cancel_backend(pid) from d4_pid;
pg_cancel_backend
-----------------
t
(1 row)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s1svpt: savepoint f;
step s1insert: insert into d4_fk values (1);
ERROR: insert or update on table "d4_fk" violates foreign key constraint "d4_fk_a_fkey"
step s1rollback: rollback to f;
step s1fetchall: fetch all from f;
a
-
2
(1 row)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s1c: commit;
starting permutation: s2snitch s1b s2detach s1declare s1svpt s1insert s1rollback s1fetchall s1c
step s2snitch: insert into d4_pid select pg_backend_pid();
step s1b: begin;
step s2detach: alter table d4_primary detach partition d4_primary1 concurrently;
step s1declare: declare f cursor for select * from d4_primary;
step s1svpt: savepoint f;
step s1insert: insert into d4_fk values (1);
ERROR: insert or update on table "d4_fk" violates foreign key constraint "d4_fk_a_fkey"
step s1rollback: rollback to f;
step s1fetchall: fetch all from f;
a
-
2
(1 row)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s1c: commit;
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
starting permutation: s2snitch s1brr s1declare2 s1fetchone s2detach s1cancel s1updcur s1c
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2snitch: insert into d4_pid select pg_backend_pid();
step s1brr: begin isolation level repeatable read;
step s1declare2: declare f cursor for select * from d4_fk where a = 2;
step s1fetchone: fetch 1 from f;
a
-
2
(1 row)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2detach: alter table d4_primary detach partition d4_primary1 concurrently; <waiting ...>
step s1cancel: select pg_cancel_backend(pid) from d4_pid; <waiting ...>
step s2detach: <... completed>
ERROR: canceling statement due to user request
step s1cancel: <... completed>
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
pg_cancel_backend
-----------------
t
(1 row)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s1updcur: update d4_fk set a = 1 where current of f;
ERROR: insert or update on table "d4_fk" violates foreign key constraint "d4_fk_a_fkey"
step s1c: commit;
starting permutation: s2snitch s1brr s1declare2 s1fetchone s2detach s1updcur s1c
step s2snitch: insert into d4_pid select pg_backend_pid();
step s1brr: begin isolation level repeatable read;
step s1declare2: declare f cursor for select * from d4_fk where a = 2;
step s1fetchone: fetch 1 from f;
a
-
2
(1 row)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2detach: alter table d4_primary detach partition d4_primary1 concurrently; <waiting ...>
step s1updcur: update d4_fk set a = 1 where current of f;
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
ERROR: insert or update on table "d4_fk" violates foreign key constraint "d4_fk_a_fkey"
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2detach: <... completed>
step s1c: commit;
starting permutation: s2snitch s1brr s1declare2 s1fetchone s1updcur s2detach s1c
step s2snitch: insert into d4_pid select pg_backend_pid();
step s1brr: begin isolation level repeatable read;
step s1declare2: declare f cursor for select * from d4_fk where a = 2;
step s1fetchone: fetch 1 from f;
a
-
2
(1 row)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s1updcur: update d4_fk set a = 1 where current of f;
step s2detach: alter table d4_primary detach partition d4_primary1 concurrently; <waiting ...>
step s1c: commit;
step s2detach: <... completed>
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
ERROR: removing partition "d4_primary1" violates foreign key constraint "d4_fk_a_fkey1"
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
starting permutation: s2snitch s1b s1s s2detach s3insert s1c
step s2snitch: insert into d4_pid select pg_backend_pid();
step s1b: begin;
step s1s: select * from d4_primary;
a
-
1
2
(2 rows)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2detach: alter table d4_primary detach partition d4_primary1 concurrently; <waiting ...>
step s3insert: insert into d4_fk values (1);
ERROR: insert or update on table "d4_fk" violates foreign key constraint "d4_fk_a_fkey"
step s1c: commit;
step s2detach: <... completed>
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
starting permutation: s2snitch s1b s1s s2detach s3brr s3insert s3commit s1cancel s1c
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2snitch: insert into d4_pid select pg_backend_pid();
step s1b: begin;
step s1s: select * from d4_primary;
a
-
1
2
(2 rows)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2detach: alter table d4_primary detach partition d4_primary1 concurrently; <waiting ...>
step s3brr: begin isolation level repeatable read;
step s3insert: insert into d4_fk values (1);
ERROR: insert or update on table "d4_fk" violates foreign key constraint "d4_fk_a_fkey"
step s3commit: commit;
step s1cancel: select pg_cancel_backend(pid) from d4_pid; <waiting ...>
step s2detach: <... completed>
ERROR: canceling statement due to user request
step s1cancel: <... completed>
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
pg_cancel_backend
-----------------
t
(1 row)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s1c: commit;
starting permutation: s2snitch s1b s1s s2detach s3brr s3insert s3commit s1c
step s2snitch: insert into d4_pid select pg_backend_pid();
step s1b: begin;
step s1s: select * from d4_primary;
a
-
1
2
(2 rows)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2detach: alter table d4_primary detach partition d4_primary1 concurrently; <waiting ...>
step s3brr: begin isolation level repeatable read;
step s3insert: insert into d4_fk values (1);
ERROR: insert or update on table "d4_fk" violates foreign key constraint "d4_fk_a_fkey"
step s3commit: commit;
step s1c: commit;
step s2detach: <... completed>
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
starting permutation: s2snitch s1brr s1s s2detach s1cancel s1noop s3vacfreeze s1s s1insert s1c
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2snitch: insert into d4_pid select pg_backend_pid();
step s1brr: begin isolation level repeatable read;
step s1s: select * from d4_primary;
a
-
1
2
(2 rows)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2detach: alter table d4_primary detach partition d4_primary1 concurrently; <waiting ...>
step s1cancel: select pg_cancel_backend(pid) from d4_pid; <waiting ...>
step s2detach: <... completed>
ERROR: canceling statement due to user request
step s1cancel: <... completed>
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
pg_cancel_backend
-----------------
t
(1 row)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
step s1noop:
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s3vacfreeze: vacuum freeze pg_catalog.pg_inherits;
step s1s: select * from d4_primary;
a
-
1
2
(2 rows)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s1insert: insert into d4_fk values (1);
Fix relcache inconsistency hazard in partition detach During queries coming from ri_triggers.c, we need to omit partitions that are marked pending detach -- otherwise, the RI query is tricked into allowing a row into the referencing table whose corresponding row is in the detached partition. Which is bogus: once the detach operation completes, the row becomes an orphan. However, the code was not doing that in repeatable-read transactions, because relcache kept a copy of the partition descriptor that included the partition, and used it in the RI query. This commit changes the partdesc cache code to only keep descriptors that aren't dependent on a snapshot (namely: those where no detached partition exist, and those where detached partitions are included). When a partdesc-without- detached-partitions is requested, we create one afresh each time; also, those partdescs are stored in PortalContext instead of CacheMemoryContext. find_inheritance_children gets a new output *detached_exist boolean, which indicates whether any partition marked pending-detach is found. Its "include_detached" input flag is changed to "omit_detached", because that name captures desired the semantics more naturally. CreatePartitionDirectory() and RelationGetPartitionDesc() arguments are identically renamed. This was noticed because a buildfarm member that runs with relcache clobbering, which would not keep the improperly cached partdesc, broke one test, which led us to realize that the expected output of that test was bogus. This commit also corrects that expected output. Author: Amit Langote <amitlangote09@gmail.com> Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Discussion: https://postgr.es/m/3269784.1617215412@sss.pgh.pa.us
2021-04-22 21:13:25 +02:00
ERROR: insert or update on table "d4_fk" violates foreign key constraint "d4_fk_a_fkey"
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s1c: commit;
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
starting permutation: s2snitch s1b s1s s2detach s1cancel s1noop s3vacfreeze s1s s1insert s1c
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2snitch: insert into d4_pid select pg_backend_pid();
step s1b: begin;
step s1s: select * from d4_primary;
a
-
1
2
(2 rows)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s2detach: alter table d4_primary detach partition d4_primary1 concurrently; <waiting ...>
step s1cancel: select pg_cancel_backend(pid) from d4_pid; <waiting ...>
step s2detach: <... completed>
ERROR: canceling statement due to user request
step s1cancel: <... completed>
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
pg_cancel_backend
-----------------
t
(1 row)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
Use annotations to reduce instability of isolation-test results. We've long contended with isolation test results that aren't entirely stable. Some test scripts insert long delays to try to force stable results, which is not terribly desirable; but other erratic failure modes remain, causing unrepeatable buildfarm failures. I've spent a fair amount of time trying to solve this by improving the server-side support code, without much success: that way is fundamentally unable to cope with diffs that stem from chance ordering of arrival of messages from different server processes. We can improve matters on the client side, however, by annotating the test scripts themselves to show the desired reporting order of events that might occur in different orders. This patch adds three types of annotations to deal with (a) test steps that might or might not complete their waits before the isolationtester can see them waiting; (b) test steps in different sessions that can legitimately complete in either order; and (c) NOTIFY messages that might arrive before or after the completion of a step in another session. We might need more annotation types later, but this seems to be enough to deal with the instabilities we've seen in the buildfarm. It also lets us get rid of all the long delays that were previously used, cutting more than a minute off the runtime of the isolation tests. Back-patch to all supported branches, because the buildfarm instabilities affect all the branches, and because it seems desirable to keep isolationtester's capabilities the same across all branches to simplify possible future back-patching of tests. Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
2021-06-23 03:43:12 +02:00
step s1noop:
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s3vacfreeze: vacuum freeze pg_catalog.pg_inherits;
step s1s: select * from d4_primary;
a
-
2
(1 row)
ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
2021-03-25 22:00:28 +01:00
step s1insert: insert into d4_fk values (1);
ERROR: insert or update on table "d4_fk" violates foreign key constraint "d4_fk_a_fkey"
step s1c: commit;