MERGE performs actions that modify rows in the target table
using a source table or query. MERGE provides a single SQL
statement that can conditionally INSERT/UPDATE/DELETE rows
a task that would other require multiple PL statements.
e.g.
MERGE INTO target AS t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED AND t.balance > s.delta THEN
UPDATE SET balance = t.balance - s.delta
WHEN MATCHED THEN
DELETE
WHEN NOT MATCHED AND s.delta > 0 THEN
INSERT VALUES (s.sid, s.delta)
WHEN NOT MATCHED THEN
DO NOTHING;
MERGE works with regular and partitioned tables, including
column and row security enforcement, as well as support for
row, statement and transition triggers.
MERGE is optimized for OLTP and is parameterizable, though
also useful for large scale ETL/ELT. MERGE is not intended
to be used in preference to existing single SQL commands
for INSERT, UPDATE or DELETE since there is some overhead.
MERGE can be used statically from PL/pgSQL.
MERGE does not yet support inheritance, write rules,
RETURNING clauses, updatable views or foreign tables.
MERGE follows SQL Standard per the most recent SQL:2016.
Includes full tests and documentation, including full
isolation tests to demonstrate the concurrent behavior.
This version written from scratch in 2017 by Simon Riggs,
using docs and tests originally written in 2009. Later work
from Pavan Deolasee has been both complex and deep, leaving
the lead author credit now in his hands.
Extensive discussion of concurrency from Peter Geoghegan,
with thanks for the time and effort contributed.
Various issues reported via sqlsmith by Andreas Seltenreich
Authors: Pavan Deolasee, Simon Riggs
Reviewers: Peter Geoghegan, Amit Langote, Tomas Vondra, Simon Riggs
Discussion:
https://postgr.es/m/CANP8+jKitBSrB7oTgT9CY2i1ObfOt36z0XMraQc+Xrz8QB0nXA@mail.gmail.comhttps://postgr.es/m/CAH2-WzkJdBuxj9PO=2QaO9-3h3xGbQPZ34kJH=HukRekwM-GZg@mail.gmail.com
Since commit 7012b132d0, postgres_fdw
has been able to push down the toplevel aggregation operation to the
remote server. Commit e2f1eb0ee3 made
it possible to break down the toplevel aggregation into one
aggregate per partition. This commit lets postgres_fdw push down
aggregation in that case just as it does at the top level.
In order to make this work, this commit adds an additional argument
to the GetForeignUpperPaths FDW API. A matching argument is added
to the signature for create_upper_paths_hook. Third-party code using
either of these will need to be updated.
Also adjust create_foreignscan_plan() so that it picks up the correct
set of relids in this case.
Jeevan Chalke, reviewed by Ashutosh Bapat and by me and with some
adjustments by me. The larger patch series of which this patch is a
part was also reviewed and tested by Antonin Houska, Rajkumar
Raghuwanshi, David Rowley, Dilip Kumar, Konstantin Knizhnik, Pascal
Legrand, and Rafia Sabih.
Discussion: http://postgr.es/m/CAM2+6=V64_xhstVHie0Rz=KPEQnLJMZt_e314P0jaT_oJ9MR8A@mail.gmail.com
Discussion: http://postgr.es/m/CAM2+6=XPWujjmj5zUaBTGDoB38CemwcPmjkRy0qOcsQj_V+2sQ@mail.gmail.com
Add a new, optional, capability to bt_index_check() and
bt_index_parent_check(): check that each heap tuple that should have an
index entry does in fact have one. The extra checking is performed at
the end of the existing nbtree checks.
This is implemented by using a Bloom filter data structure. The
implementation performs set membership tests within a callback (the same
type of callback that each index AM registers for CREATE INDEX). The
Bloom filter is populated during the initial index verification scan.
Reusing the CREATE INDEX infrastructure allows the new verification
option to automatically benefit from the heap consistency checks that
CREATE INDEX already performs. CREATE INDEX does thorough sanity
checking of HOT chains, so the new check actually manages to detect
problems in heap-only tuples.
Author: Peter Geoghegan
Reviewed-By: Pavan Deolasee, Andres Freund
Discussion: https://postgr.es/m/CAH2-Wzm5VmG7cu1N-H=nnS57wZThoSDQU+F5dewx3o84M+jY=g@mail.gmail.com
Previously there was no way in the standby side to find out the host and port
of the sender server that the walreceiver was currently connected to when
multiple hosts and ports were specified in primary_conninfo. For that purpose,
this patch adds sender_host and sender_port columns into pg_stat_wal_receiver
view. They report the host and port that the active replication connection
currently uses.
Bump catalog version.
Author: Haribabu Kommi
Reviewed-by: Michael Paquier and me
Discussion: https://postgr.es/m/CAJrrPGcV_aq8=cdqkFhVDJKEnDQ70yRTTdY9RODzMnXNrCz2Ow@mail.gmail.com
Previously, committing or aborting inside a cursor loop was prohibited
because that would close and remove the cursor. To allow that,
automatically convert such cursors to holdable cursors so they survive
commits or rollbacks. Portals now have a new state "auto-held", which
means they have been converted automatically from pinned. An auto-held
portal is kept on transaction commit or rollback, but is still removed
when returning to the main loop on error.
This supports all languages that have cursor loop constructs: PL/pgSQL,
PL/Python, PL/Perl.
Reviewed-by: Ildus Kurbangaliev <i.kurbangaliev@postgrespro.ru>
As promised in earlier commits, this adds documentation about the new
build options, the new GUCs, about the planner logic when JIT is used,
and the benefits of JIT in general.
Also adds a more implementation oriented README.
I'm sure we're going to want to expand this further, but I think this
is a reasonable start.
Author: Andres Freund, with contributions by Thomas Munro
Reviewed-By: Thomas Munro
Discussion: https://postgr.es/m/20170901064131.tazjxwus3k2w3ybh@alap3.anarazel.de
The target cluster that was rewound needs to perform recovery from
the checkpoint created at failover, which leads it to remove or recreate
some files and directories that may have been copied from the source
cluster. So pg_rewind can skip synchronizing such files and directories,
and which reduces the amount of data transferred during a rewind
without changing the usefulness of the operation.
Author: Michael Paquier
Reviewed-by: Anastasia Lubennikova, Stephen Frost and me
Discussion: https://postgr.es/m/20180205071022.GA17337@paquier.xyz
So far, a nested CALL or DO in PL/pgSQL would not establish a context
where transaction control statements were allowed. This fixes that by
handling CALL and DO specially in PL/pgSQL, passing the atomic/nonatomic
execution context through and doing the required management around
transaction boundaries.
Reviewed-by: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Add a new contrib module jsonb_plpython that provide a transform between
jsonb and PL/Python. jsonb values are converted to appropriate Python
types such as dicts and lists, and vice versa.
Author: Anthony Bykov <a.bykov@postgrespro.ru>
Reviewed-by: Aleksander Alekseev <a.alekseev@postgrespro.ru>
Reviewed-by: Nikita Glukhov <n.gluhov@postgrespro.ru>
Currently adding a column to a table with a non-NULL default results in
a rewrite of the table. For large tables this can be both expensive and
disruptive. This patch removes the need for the rewrite as long as the
default value is not volatile. The default expression is evaluated at
the time of the ALTER TABLE and the result stored in a new column
(attmissingval) in pg_attribute, and a new column (atthasmissing) is set
to true. Any existing row when fetched will be supplied with the
attmissingval. New rows will have the supplied value or the default and
so will never need the attmissingval.
Any time the table is rewritten all the atthasmissing and attmissingval
settings for the attributes are cleared, as they are no longer needed.
The most visible code change from this is in heap_attisnull, which
acquires a third TupleDesc argument, allowing it to detect a missing
value if there is one. In many cases where it is known that there will
not be any (e.g. catalog relations) NULL can be passed for this
argument.
Andrew Dunstan, heavily modified from an original patch from Serge
Rielau.
Reviewed by Tom Lane, Andres Freund, Tomas Vondra and David Rowley.
Discussion: https://postgr.es/m/31e2e921-7002-4c27-59f5-51f08404c858@2ndQuadrant.com
If the value of an index expression is unchanged after UPDATE,
allow HOT updates where previously we disallowed them, giving
a significant performance boost in those cases.
Particularly useful for indexes such as JSON->>field where the
JSON value changes but the indexed value does not.
Submitted as "surjective indexes" patch, now enabled by use
of new "recheck_on_update" parameter.
Author: Konstantin Knizhnik
Reviewer: Simon Riggs, with much wordsmithing and some cleanup
Previously, PQhost didn't return the connected host details when the
connection type was CHT_HOST_ADDRESS (i.e., via hostaddr). Instead, it
returned the complete host connection parameter (which could contain
multiple hosts) or the default host details, which was confusing and
arguably incorrect.
Change this to return the actually connected host or hostaddr
irrespective of the connection type. When hostaddr but no host was
specified, hostaddr is now returned. Never return the original host
connection parameter, and document that PQhost cannot be relied on
before the connection is established.
PQport is similarly changed to always return the active connection port
and never the original connection parameter.
Author: Hari Babu <kommi.haribabu@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>
Reviewed-by: David G. Johnston <david.g.johnston@gmail.com>
Setting random could increase reproducibility of test in some cases. Patch
suggests three providers for seed: time (default), strong random
generator (if available) and unsigned constant. Seed could be set from
command line or enviroment variable.
Author: Fabien Coelho
Reviewed by: Chapman Flack
Discussion: https://www.postgresql.org/message-id/flat/20160407082711.q7iq3ykffqxcszkv@alap3.anarazel.de
Commit eb7ed3f306 enabled unique constraints on partitioned tables,
but one thing that was not working properly is INSERT/ON CONFLICT.
This commit introduces a new node keeps state related to the ON CONFLICT
clause per partition, and fills it when that partition is about to be
used for tuple routing.
Author: Amit Langote, Álvaro Herrera
Reviewed-by: Etsuro Fujita, Pavan Deolasee
Discussion: https://postgr.es/m/20180228004602.cwdyralmg5ejdqkq@alvherre.pgsql
Section 10.5 didn't say explicitly that multiple UNIONs are resolved
pairwise. Since the resolution algorithm is described as taking any
number of inputs, readers might well think that a query like
"select x union select y union select z" would be resolved by
considering x, y, and z in one resolution step. But that's not what
happens (and I think that behavior is per SQL spec). Add an example
clarifying this point.
Per bug #15129 from Philippe Beaudoin.
Discussion: https://postgr.es/m/152196085023.32649.9916472370480121694@wrigleys.postgresql.org
This adds a new option --wal-segsize (analogous to initdb) that changes
the WAL segment size in pg_control.
Author: Nathan Bossart <bossartn@amazon.com>
We were running out of good single-letter options for some upcoming
pg_resetwal functionality, so add long options to create more
possibilities. Add to pg_controldata as well for symmetry.
based on patch by Bossart, Nathan <bossartn@amazon.com>
Clarify that the -l option takes a file name, not an "address", and that
that might be different from the LSN if nondefault WAL segment sizes are
used.
Extension scripts begin execution with pg_catalog at the front of the
search path, so type names reliably refer to pg_catalog. Remove these
superfluous qualifications. Earlier <programlisting> of this <sect1>
already omitted them. Back-patch to 9.3 (all supported versions).
Previously, FOR EACH ROW triggers were not allowed in partitioned
tables. Now we allow AFTER triggers on them, and on trigger creation we
cascade to create an identical trigger in each partition. We also clone
the triggers to each partition that is created or attached later.
This means that deferred unique keys are allowed on partitioned tables,
too.
Author: Álvaro Herrera
Reviewed-by: Peter Eisentraut, Simon Riggs, Amit Langote, Robert Haas,
Thomas Munro
Discussion: https://postgr.es/m/20171229225319.ajltgss2ojkfd3kp@alvherre.pgsql
VACUUM thought that reltuples represents the total number of tuples in
the relation, while ANALYZE counted only live tuples. This can cause
"flapping" in the value when background vacuums and analyzes happen
separately. The planner's use of reltuples essentially assumes that
it's the count of live (visible) tuples, so let's standardize on having
it mean live tuples.
Another issue is that the definition of "live tuple" isn't totally clear;
what should be done with INSERT_IN_PROGRESS or DELETE_IN_PROGRESS tuples?
ANALYZE's choices in this regard are made on the assumption that if the
originating transaction commits at all, it will happen after ANALYZE
finishes, so we should ignore the effects of the in-progress transaction
--- unless it is our own transaction, and then we should count it.
Let's propagate this definition into VACUUM, too.
Likewise propagate this definition into CREATE INDEX, and into
contrib/pgstattuple's pgstattuple_approx() function.
Tomas Vondra, reviewed by Haribabu Kommi, some corrections by me
Discussion: https://postgr.es/m/16db4468-edfa-830a-f921-39a50498e77e@2ndquadrant.com
If the partition keys of input relation are part of the GROUP BY
clause, all the rows belonging to a given group come from a single
partition. This allows aggregation/grouping over a partitioned
relation to be broken down * into aggregation/grouping on each
partition. This should be no worse, and often better, than the normal
approach.
If the GROUP BY clause does not contain all the partition keys, we can
still perform partial aggregation for each partition and then finalize
aggregation after appending the partial results. This is less certain
to be a win, but it's still useful.
Jeevan Chalke, Ashutosh Bapat, Robert Haas. The larger patch series
of which this patch is a part was also reviewed and tested by Antonin
Houska, Rajkumar Raghuwanshi, David Rowley, Dilip Kumar, Konstantin
Knizhnik, Pascal Legrand, and Rafia Sabih.
Discussion: http://postgr.es/m/CAM2+6=V64_xhstVHie0Rz=KPEQnLJMZt_e314P0jaT_oJ9MR8A@mail.gmail.com
Logical decoding should not publish anything about tables created as
part of a heap rewrite during DDL. Those tables don't exist externally,
so consumers of logical decoding cannot do anything sensible with that
information. In ab28feae2b, we worked
around this for built-in logical replication, but that was hack.
This is a more proper fix: We mark such transient heaps using the new
field pg_class.relwrite, linking to the original relation OID. By
default, we ignore them in logical decoding before they get to the
output plugin. Optionally, a plugin can register their interest in
getting such changes, if they handle DDL specially, in which case the
new field will help them get information about the actual table.
Reviewed-by: Craig Ringer <craig@2ndquadrant.com>
This is an optional dependency. It'll be used for the upcoming LLVM
based just in time compilation support, which needs to wrap a few LLVM
C++ APIs so they're accessible from C..
For now test for C++ compilers unconditionally, without failing if not
present, to ensure wide buildfarm coverage. If we're bothered by the
additional test times (which are quite short) or verbosity, we can
later make the tests conditional on --with-llvm.
Author: Andres Freund
Discussion: https://postgr.es/m/20170901064131.tazjxwus3k2w3ybh@alap3.anarazel.de
If a view lacks an INSTEAD OF trigger, DML on it can only work by rewriting
the command into a command on the underlying base table(s). Then we will
fire triggers attached to those table(s), not those for the view. This
seems appropriate from a consistency standpoint, but nowhere was the
behavior explicitly documented, so let's do that.
There was some discussion of throwing an error or warning if a statement
trigger is created on a view without creating a row INSTEAD OF trigger.
But a simple implementation of that would result in dump/restore ordering
hazards. Given that it's been like this all along, and we hadn't heard
a complaint till now, a documentation improvement seems sufficient.
Per bug #15106 from Pu Qun. Back-patch to all supported branches.
Discussion: https://postgr.es/m/152083391168.1215.16892140713507052796@wrigleys.postgresql.org
Since SSL compression is no longer recommended, turn the default in
libpq from on to off.
OpenSSL 1.1.0 and many distribution packages already turn compression
off by default, so such a server won't accept compression anyway. So
this will mainly affect users of older OpenSSL installations.
Also update the documentation to make clear that this setting is no
longer recommended.
Discussion: https://www.postgresql.org/message-id/flat/595cf3b1-4ffe-7f05-6f72-f72b7afa7993%402ndquadrant.com
This allows specifying an external command for prompting for or
otherwise obtaining passphrases for SSL key files. This is useful
because in many cases there is no TTY easily available during service
startup.
Also add a setting ssl_passphrase_command_supports_reload, which allows
supporting SSL configuration reload even if SSL files need passphrases.
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
In a top-level CALL, the values of INOUT arguments will be returned as a
result row. In PL/pgSQL, the values are assigned back to the input
arguments. In other languages, the same convention as for return a
record from a function is used. That does not require any code changes
in the PL implementations.
Reviewed-by: Pavel Stehule <pavel.stehule@gmail.com>