Commit Graph

17387 Commits

Author SHA1 Message Date
Tom Lane 9bf4068cc3 Fix datumSerialize infrastructure to not crash on non-varlena data.
Commit 1efc7e538 did a poor job of emulating existing logic for touching
Datums that might be expanded-object pointers.  It didn't check for typlen
being -1 first, which meant it could crash on fixed-length pass-by-ref
values, and probably on cstring values as well.  It also didn't use
DatumGetPointer before VARATT_IS_EXTERNAL_EXPANDED, which while currently
harmless is not according to documentation nor prevailing style.

I also think the lack of any explanation as to why datumSerialize makes
these particular nonobvious choices is pretty awful, so fix that.

Per report from Jarred Ward.  Back-patch to 9.6 where this code came in.

Discussion: https://postgr.es/m/6F61E6D2-2F5E-4794-9479-A429BE1CEA4B@simple.com
2017-08-08 19:18:22 -04:00
Alvaro Herrera 77d2c00af7 Reword some unclear comments 2017-08-08 18:48:01 -04:00
Alvaro Herrera f5d54ef97a Fix typo in comment 2017-08-08 18:34:25 -04:00
Alvaro Herrera b2c95a3798 Fix replication origin-related race conditions
Similar to what was fixed in commit 9915de6c1c for replication slots,
but this time it's related to replication origins: DROP SUBSCRIPTION
attempts to drop the replication origin, but that fails if the
replication worker process hasn't yet marked it unused.  This causes
failures in the buildfarm:
ERROR:  could not drop replication origin with OID 1, in use by PID 34069

Like the aforementioned commit, fix by having the process running DROP
SUBSCRIPTION sleep until the worker marks the the replication origin
struct as free.  This uses a condition variable on each replication
origin shmem state struct, so that the session trying to drop can sleep
and expect to be awakened by the process keeping the origin open.

Also fix a SGML markup in the previous commit.

Discussion: https://postgr.es/m/20170808001433.rozlseaf4m2wkw3n@alvherre.pgsql
2017-08-08 16:07:46 -04:00
Alvaro Herrera 030273b7ea Fix inadequacies in recently added wait events
In commit 9915de6c1c, we introduced a new wait point for replication
slots and incorrectly labelled it as wait event PG_WAIT_LOCK.  That's
wrong, so invent an appropriate new wait event instead, and document it
properly.

While at it, fix numerous other problems in the vicinity:
- two different walreceiver wait events were being mixed up in a single
  wait event (which wasn't documented either); split it out so that they
  can be distinguished, and document the new events properly.

- ParallelBitmapPopulate was documented but didn't exist.

- ParallelBitmapScan was not documented (I think this should be called
  "ParallelBitmapScanInit" instead.)

- Logical replication wait events weren't documented

- various symbols had been added in dartboard order in various places.
  Put them in alphabetical order instead, as was originally intended.

Discussion: https://postgr.es/m/20170808181131.mu4fjepuh5m75cyq@alvherre.pgsql
2017-08-08 15:37:44 -04:00
Peter Eisentraut cdc47d1f39 Update SQL features list 2017-08-07 14:30:24 -04:00
Peter Eisentraut f7668b2b35 Translation updates
Source-Git-URL: git://git.postgresql.org/git/pgtranslation/messages.git
Source-Git-Hash: 1a0b5e655d7871506c2b1c7ba562c2de6b6a55de
2017-08-07 13:55:34 -04:00
Peter Eisentraut fca17a933b Fix local/remote attribute mix-up in logical replication
This would lead to failures if local and remote tables have a different
column order.  The tests previously didn't catch that because they only
tested the initial data copy.  So add another test that exercises the
apply worker.

Author: Petr Jelinek <petr.jelinek@2ndquadrant.com>
2017-08-07 10:49:08 -04:00
Peter Eisentraut 0e58455dd4 Fix handling of dropped columns in logical replication
The relation attribute map was not initialized for dropped columns,
leading to errors later on.

Author: Petr Jelinek <petr.jelinek@2ndquadrant.com>
Reported-by: Scott Milliken <scott@deltaex.com>
Bug: #14769
2017-08-07 10:28:35 -04:00
Tom Lane 8d9881911f Require update permission for the large object written by lo_put().
lo_put() surely should require UPDATE permission, the same as lowrite(),
but it failed to check for that, as reported by Chapman Flack.  Oversight
in commit c50b7c09d; backpatch to 9.4 where that was introduced.

Tom Lane and Michael Paquier

Security: CVE-2017-7548
2017-08-07 10:19:19 -04:00
Noah Misch e568e1eee4 Again match pg_user_mappings to information_schema.user_mapping_options.
Commit 3eefc51053 claimed to make
pg_user_mappings enforce the qualifications user_mapping_options had
been enforcing, but its removal of a longstanding restriction left them
distinct when the current user is the subject of a mapping yet has no
server privileges.  user_mapping_options emits no rows for such a
mapping, but pg_user_mappings includes full umoptions.  Change
pg_user_mappings to show null for umoptions.  Back-patch to 9.2, like
the above commit.

Reviewed by Tom Lane.  Reported by Jeff Janes.

Security: CVE-2017-7547
2017-08-07 07:09:28 -07:00
Heikki Linnakangas bf6b9e9444 Don't allow logging in with empty password.
Some authentication methods allowed it, others did not. In the client-side,
libpq does not even try to authenticate with an empty password, which makes
using empty passwords hazardous: an administrator might think that an
account with an empty password cannot be used to log in, because psql
doesn't allow it, and not realize that a different client would in fact
allow it. To clear that confusion and to be be consistent, disallow empty
passwords in all authentication methods.

All the authentication methods that used plaintext authentication over the
wire, except for BSD authentication, already checked that the password
received from the user was not empty. To avoid forgetting it in the future
again, move the check to the recv_password_packet function. That only
forbids using an empty password with plaintext authentication, however.
MD5 and SCRAM need a different fix:

* In stable branches, check that the MD5 hash stored for the user does not
not correspond to an empty string. This adds some overhead to MD5
authentication, because the server needs to compute an extra MD5 hash, but
it is not noticeable in practice.

* In HEAD, modify CREATE and ALTER ROLE to clear the password if an empty
string, or a password hash that corresponds to an empty string, is
specified. The user-visible behavior is the same as in the stable branches,
the user cannot log in, but it seems better to stop the empty password from
entering the system in the first place. Secondly, it is fairly expensive to
check that a SCRAM hash doesn't correspond to an empty string, because
computing a SCRAM hash is much more expensive than an MD5 hash by design,
so better avoid doing that on every authentication.

We could clear the password on CREATE/ALTER ROLE also in stable branches,
but we would still need to check at authentication time, because even if we
prevent empty passwords from being stored in pg_authid, there might be
existing ones there already.

Reported by Jeroen van der Ham, Ben de Graaff and Jelte Fennema.

Security: CVE-2017-7546
2017-08-07 17:03:42 +03:00
Peter Eisentraut 86524f0387 Fix function name in code comment
Reported-by: Peter Geoghegan <pg@bowt.ie>
2017-08-07 09:49:55 -04:00
Peter Eisentraut ad2ca3cba6 Improve wording of subscription refresh debug messages
Reported-by: Yugo Nagata <nagata@sraoss.co.jp>
2017-08-07 09:40:12 -04:00
Peter Eisentraut 6f81306e4d Downgrade subscription refresh messages to DEBUG1
The NOTICE messages about tables being added or removed during
subscription refresh would be incorrect and possibly confusing if the
transaction rolls back, so silence them but keep them available for
debugging.

Discussion: https://www.postgresql.org/message-id/CAD21AoAvaXizc2h7aiNyK_i0FQSa-tmhpdOGwbhh7Jy544Ad4Q%40mail.gmail.com
2017-08-07 09:16:03 -04:00
Andres Freund 5af4456a56 Fix thinko introduced in 2bef06d516 et al.
The callers for GetOldestSafeDecodingTransactionId() all inverted the
argument for the argument introduced in 2bef06d516. Luckily this
appears to be inconsequential for the moment, as we wait for
concurrent in-progress transaction when assembling a
snapshot. Additionally this could only make a difference when adding a
second logical slot, because only a pre-existing slot could cause an
issue by lowering the returned xid dangerously much.

Reported-By: Antonin Houska
Discussion: https://postgr.es/m/32704.1496993134@localhost
Backport: 9.4-, where 2bef06d516 was backpatched to.
2017-08-06 14:20:55 -07:00
Tom Lane e9f4ac1389 Suppress unused-variable warnings when building with ICU 4.2.
Tidy-up for commit eccead9ed.
2017-08-05 11:48:43 -04:00
Robert Haas 52f8a59dd9 Make pg_stop_backup's wait_for_archive flag work on standbys.
Previously, it had no effect.  Now, if archive_mode=always, it will
work, and if not, you'll get a warning.

Masahiko Sawada, Michael Paquier, and Robert Haas.  The patch as
submitted also changed the behavior so that we would write and remove
history files on standbys, but that seems like material for a separate
patch to me.

Discussion: http://postgr.es/m/CAD21AoC2Xw6M=ZJyejq_9d_iDkReC_=rpvQRw5QsyzKQdfYpkw@mail.gmail.com
2017-08-05 10:49:26 -04:00
Peter Eisentraut eccead9ed4 Add support for ICU 4.2
Supporting ICU 4.2 seems useful because it ships with CentOS 6.

Versions before ICU 4.6 don't support pkg-config, so document an
installation method without using pkg-config.

In ICU 4.2, ucol_getKeywordsForLocale() sometimes returns values that
will not be accepted by uloc_toLanguageTag().  Skip loading keyword
variants in that version.

Reported-by: Victor Wagner <vitus@wagner.pp.ru>
2017-08-05 09:32:42 -04:00
Robert Haas f85f88bcc2 Fix bug in deciding whether to scan newly-attached partition.
If the table being attached had different attribute numbers than the
parent, the old code could incorrectly decide it needed to be scanned.

Amit Langote, reviewed by Ashutosh Bapat

Discussion: http://postgr.es/m/CA+TgmobexgbBr2+Utw-pOMw9uxaBRKRjMW_-mmzKKx9PejPLMg@mail.gmail.com
2017-08-04 22:01:37 -04:00
Peter Eisentraut 7e174fa793 Only kill sync workers at commit time in subscription DDL
This allows a transaction abort to avoid killing those workers.

Author: Petr Jelinek <petr.jelinek@2ndquadrant.com>
2017-08-04 21:17:47 -04:00
Robert Haas ff98a5e1e4 hash: Immediately after a bucket split, try to clean the old bucket.
If it works, then we won't be storing two copies of all the tuples
that were just moved.  If not, VACUUM will still take care of it
eventually.  Per a report from AP and analysis from Amit Kapila, it
seems that a bulk load can cause splits fast enough that VACUUM won't
deal with the problem in time to prevent bloat.

Amit Kapila; I rewrote the comment.

Discussion: http://postgr.es/m/20170704105728.mwb72jebfmok2nm2@zip.com.au
2017-08-04 19:33:01 -04:00
Tom Lane c30f1770a9 Apply ALTER ... SET NOT NULL recursively in ALTER ... ADD PRIMARY KEY.
If you do ALTER COLUMN SET NOT NULL against an inheritance parent table,
it will recurse to mark all the child columns as NOT NULL as well.  This
is necessary for consistency: if the column is labeled NOT NULL then
reading it should never produce nulls.

However, that didn't happen in the case where ALTER ... ADD PRIMARY KEY
marks a target column NOT NULL that wasn't before.  That was questionable
from the beginning, and now Tushar Ahuja points out that it can lead to
dump/restore failures in some cases.  So let's make that case recurse too.

Although this is meant to fix a bug, it's enough of a behavioral change
that I'm pretty hesitant to back-patch, especially in view of the lack
of similar field complaints.  It doesn't seem to be too late to put it
into v10 though.

Michael Paquier, editorialized on slightly by me

Discussion: https://postgr.es/m/b8794d6a-38f0-9d7c-ad4b-e85adf860fc9@enterprisedb.com
2017-08-04 11:45:18 -04:00
Tom Lane 97d3a0b090 Disallow SSL session tickets.
We don't actually support session tickets, since we do not create an SSL
session identifier.  But it seems that OpenSSL will issue a session ticket
on-demand anyway, which will then fail when used.  This results in
reconnection failures when using ticket-aware client-side SSL libraries
(such as the Npgsql .NET driver), as reported by Shay Rojansky.

To fix, just tell OpenSSL not to issue tickets.  At some point in the
far future, we might consider enabling tickets instead.  But the security
implications of that aren't entirely clear; and besides it would have
little benefit except for very short-lived database connections, which is
Something We're Bad At anyhow.  It would take a lot of other work to get
to a point where that would really be an exciting thing to do.

While at it, also tell OpenSSL not to use a session cache.  This doesn't
really do anything, since a backend would never populate the cache anyway,
but it might gain some micro-efficiencies and/or reduce security
exposures.

Patch by me, per discussion with Heikki Linnakangas and Shay Rojansky.
Back-patch to all supported versions.

Discussion: https://postgr.es/m/CADT4RqBU8N-csyZuzaook-c795dt22Zcwg1aHWB6tfVdAkodZA@mail.gmail.com
2017-08-04 11:07:10 -04:00
Peter Eisentraut b374481221 Further unify ROLE and USER command grammar rules
ALTER USER ... SET did not support all the syntax variants of ALTER ROLE
...  SET.  Fix that, and to avoid further deviations of this kind, unify
many the grammar rules for ROLE/USER/GROUP commands.

Reported-by: Pavel Golub <pavel@microolap.com>
2017-08-03 20:34:45 -04:00
Robert Haas 972b6ec20b Fix lock upgrade hazard in ATExecAttachPartition.
Amit Langote

Discussion: http://postgr.es/m/CAFjFpReT_kq_uwU_B8aWDxR7jNGE=P0iELycdq5oupi=xSQTOw@mail.gmail.com
2017-08-03 14:21:00 -04:00
Robert Haas 583df3b5c5 Code beautification for ATExecAttachPartition.
Amit Langote

Discussion: http://postgr.es/m/CAFjFpReT_kq_uwU_B8aWDxR7jNGE=P0iELycdq5oupi=xSQTOw@mail.gmail.com
2017-08-03 14:19:59 -04:00
Robert Haas 86705aa8c3 Allow a foreign table CHECK constraint to be initially NOT VALID.
For a table, the constraint can be considered validated immediately,
because the table must be empty.  But for a foreign table this is
not necessarily the case.

Fixes a bug in commit f27a6b15e6.

Amit Langote, with some changes by me.

Discussion: http://postgr.es/m/d2b7419f-4a71-cf86-cc99-bfd0f359a1ea@lab.ntt.co.jp
2017-08-03 13:24:48 -04:00
Robert Haas 12a34f59bf Improve ExecModifyTable comments.
Some of these comments wrongly implied that only an AFTER ROW trigger
will cause a 'wholerow' attribute to be present for a foreign table,
but a BEFORE ROW trigger can have the same effect.  Others implied
that it would always be present for a foreign table, but that's not
true either.

Etsuro Fujita and Robert Haas

Discussion: http://postgr.es/m/10026bc7-1403-ef85-9e43-c6100c1cc0e3@lab.ntt.co.jp
2017-08-03 12:47:00 -04:00
Robert Haas 610e8ebb0f Teach map_partition_varattnos to handle whole-row expressions.
Otherwise, partitioned tables with RETURNING expressions or subject
to a WITH CHECK OPTION do not work properly.

Amit Langote, reviewed by Amit Khandekar and Etsuro Fujita.  A few
comment changes by me.

Discussion: http://postgr.es/m/9a39df80-871e-6212-0684-f93c83be4097@lab.ntt.co.jp
2017-08-03 11:21:29 -04:00
Tom Lane 9d4e566999 Remove broken and useless entry-count printing in HASH_DEBUG code.
init_htab(), with #define HASH_DEBUG, prints a bunch of hashtable
parameters.  It used to also print nentries, but commit 44ca4022f changed
that to "hash_get_num_entries(hctl)", which is wrong (the parameter should
be "hashp").

Rather than correct the coding, though, let's just remove that field from
the printout.  The table must be empty, since we just finished building
it, so expensively calculating the number of entries is rather pointless.
Moreover hash_get_num_entries makes assumptions (about not needing locks)
which we could do without in debugging code.

Noted by Choi Doo-Won in bug #14764.  Back-patch to 9.6 where the
faulty code was introduced.

Discussion: https://postgr.es/m/20170802032353.8424.12274@wrigleys.postgresql.org
2017-08-02 12:17:08 -04:00
Peter Eisentraut cf65201833 Get a snapshot before COPY in table sync
This fixes a crash if the local table has a function index and the
function makes non-immutable calls.

Reported-by: Scott Milliken <scott@deltaex.com>
Author: Masahiko Sawada <sawada.mshk@gmail.com>
2017-08-02 11:34:42 -04:00
Tom Lane f352f91cbf Remove duplicate setting of SSL_OP_SINGLE_DH_USE option.
Commit c0a15e07c moved the setting of OpenSSL's SSL_OP_SINGLE_DH_USE option
into a new subroutine initialize_dh(), but forgot to remove it from where
it was.  SSL_CTX_set_options() is a trivial function, amounting indeed to
just "ctx->options |= op", hence there's no reason to contort the code or
break separation of concerns to avoid calling it twice.  So separating the
DH setup from disabling of old protocol versions is a good change, but we
need to finish the job.

Noted while poking into the question of SSL session tickets.
2017-08-02 11:28:49 -04:00
Peter Eisentraut 41cefbb6db Fix OBJECT_TYPE/OBJECT_DOMAIN confusion
This doesn't have a significant impact except that now SECURITY LABEL ON
DOMAIN rejects types that are not domains.

Reported-by: 高增琦 <pgf00a@gmail.com>
2017-08-02 10:40:32 -04:00
Tom Lane 514f613293 Second try at getting useful errors out of newlocale/_create_locale.
The early buildfarm returns for commit 1e165d05f are pretty awful:
not only does Windows not return a useful error, but it looks like
a lot of Unix-ish platforms don't either.  Given the number of
different errnos seen so far, guess that what's really going on is
that some newlocale() implementations fail to set errno at all.
Hence, let's try zeroing errno just before newlocale() and then
if it's still zero report as though it's ENOENT.  That should cover
the Windows case too.

It's clear that we'll have to drop the regression test case, unless
we want to maintain a separate expected-file for platforms without
HAVE_LOCALE_T.  But I'll leave it there awhile longer to see if this
actually improves matters or not.

Discussion: https://postgr.es/m/CAKKotZS-wcDcofXDCH=sidiuajE+nqHn2CGjLLX78anyDmi3gQ@mail.gmail.com
2017-08-01 17:17:20 -04:00
Tom Lane 1e165d05fe Try to deliver a sane message for _create_locale() failure on Windows.
We were just printing errno, which is certainly not gonna work on
Windows.  Now, it's not entirely clear from Microsoft's documentation
whether _create_locale() adheres to standard Windows error reporting
conventions, but let's assume it does and try to map the GetLastError
result to an errno.  If this turns out not to work, probably the best
thing to do will be to assume the error is always ENOENT on Windows.

This is a longstanding bug, but given the lack of previous field
complaints, I'm not excited about back-patching it.

Per report from Murtuza Zabuawala.

Discussion: https://postgr.es/m/CAKKotZS-wcDcofXDCH=sidiuajE+nqHn2CGjLLX78anyDmi3gQ@mail.gmail.com
2017-08-01 16:11:51 -04:00
Tom Lane f97256570f Allow creation of C/POSIX collations without depending on libc behavior.
Most of our collations code has special handling for the locale names
"C" and "POSIX", allowing those collations to be used whether or not
the system libraries think those locale names are valid, or indeed
whether said libraries even have any locale support.  But we missed
handling things that way in CREATE COLLATION.  This meant you couldn't
clone the C/POSIX collations, nor explicitly define a new collation
using those locale names, unless the libraries allow it.  That's pretty
pointless, as well as being a violation of pg_newlocale_from_collation's
API specification.

The practical effect of this change is quite limited: it allows creating
such collations even on platforms that don't HAVE_LOCALE_T, and it allows
making "POSIX" collation objects on Windows, which before this would only
let you make "C" collation objects.  Hence, even though this is a bug fix
IMO, it doesn't seem worth the trouble to back-patch.

In passing, suppress the DROP CASCADE detail messages at the end of the
collation regression test.  I'm surprised we've never been bit by
message ordering issues there.

Per report from Murtuza Zabuawala.

Discussion: https://postgr.es/m/CAKKotZS-wcDcofXDCH=sidiuajE+nqHn2CGjLLX78anyDmi3gQ@mail.gmail.com
2017-08-01 13:51:05 -04:00
Dean Rasheed 4de6216877 Comment fix for partition_rbound_cmp().
This was an oversight in d363d42.

Beena Emerson
2017-08-01 09:40:45 +01:00
Peter Eisentraut f40254a799 Fix typo
Author: Etsuro Fujita <fujita.etsuro@lab.ntt.co.jp>
2017-07-31 17:08:14 -04:00
Heikki Linnakangas c0a15e07cd Always use 2048 bit DH parameters for OpenSSL ephemeral DH ciphers.
1024 bits is considered weak these days, but OpenSSL always passes 1024 as
the key length to the tmp_dh callback. All the code to handle other key
lengths is, in fact, dead.

To remedy those issues:

* Only include hard-coded 2048-bit parameters.
* Set the parameters directly with SSL_CTX_set_tmp_dh(), without the
  callback
* The name of the file containing the DH parameters is now a GUC. This
  replaces the old hardcoded "dh1024.pem" filename. (The files for other
  key lengths, dh512.pem, dh2048.pem, etc. were never actually used.)

This is not a new problem, but it doesn't seem worth the risk and churn to
backport. If you care enough about the strength of the DH parameters on
old versions, you can create custom DH parameters, with as many bits as you
wish, and put them in the "dh1024.pem" file.

Per report by Nicolas Guini and Damian Quiroga. Reviewed by Michael Paquier.

Discussion: https://www.postgresql.org/message-id/CAMxBoUyjOOautVozN6ofzym828aNrDjuCcOTcCquxjwS-L2hGQ@mail.gmail.com
2017-07-31 22:36:09 +03:00
Tatsuo Ishii 393d47ed0f Add missing comment in postgresql.conf.
current_source requires to restart server to reflect the new
value. Per Yugo Nagata and Masahiko Sawada.

Back patched to 9.2 and beyond.
2017-07-31 11:24:51 +09:00
Tatsuo Ishii 8b015dd723 Add missing comment in postgresql.conf.
dynamic_shared_memory_type requires to restart server to reflect
the new value. Per Yugo Nagata and Masahiko Sawada.

Back pached to 9.4 and beyond.
2017-07-31 11:06:37 +09:00
Tatsuo Ishii 9fe63092b5 Add missing comment in postgresql.conf.
max_logical_replication_workers requires to restart server to reflect
the new value. Per Yugo Nagata. Minor editing by me.
2017-07-31 10:46:32 +09:00
Andres Freund cc9f08b6b8 Move ExecProcNode from dispatch to function pointer based model.
This allows us to add stack-depth checks the first time an executor
node is called, and skip that overhead on following
calls. Additionally it yields a nice speedup.

While it'd probably have been a good idea to have that check all
along, it has become more important after the new expression
evaluation framework in b8d7f053c5 - there's no stack depth
check in common paths anymore now. We previously relied on
ExecEvalExpr() being executed somewhere.

We should move towards that model for further routines, but as this is
required for v10, it seems better to only do the necessary (which
already is quite large).

Author: Andres Freund, Tom Lane
Reported-By: Julien Rouhaud
Discussion:
    https://postgr.es/m/22833.1490390175@sss.pgh.pa.us
    https://postgr.es/m/b0af9eaa-130c-60d0-9e4e-7a135b1e0c76@dalibo.com
2017-07-30 16:18:21 -07:00
Andres Freund d47cfef711 Move interrupt checking from ExecProcNode() to executor nodes.
In a followup commit ExecProcNode(), and especially the large switch
it contains, will largely be replaced by a function pointer directly
to the correct node. The node functions will then get invoked by a
thin inline function wrapper. To avoid having to include miscadmin.h
in headers - CHECK_FOR_INTERRUPTS() - move the interrupt checks into
the individual executor routines.

While looking through all executor nodes, I noticed a number of
arguably missing interrupt checks, add these too.

Author: Andres Freund, Tom Lane
Reviewed-By: Tom Lane
Discussion:
    https://postgr.es/m/22833.1490390175@sss.pgh.pa.us
2017-07-30 16:06:42 -07:00
Alvaro Herrera 5e3254f086 Update copyright in recently added files 2017-07-26 18:17:18 -04:00
Alvaro Herrera 459c64d322 Fix concurrent locking of tuple update chain
If several sessions are concurrently locking a tuple update chain with
nonconflicting lock modes using an old snapshot, and they all succeed,
it may happen that some of them fail because of restarting the loop (due
to a concurrent Xmax change) and getting an error in the subsequent pass
while trying to obtain a tuple lock that they already have in some tuple
version.

This can only happen with very high concurrency (where a row is being
both updated and FK-checked by multiple transactions concurrently), but
it's been observed in the field and can have unpleasant consequences
such as an FK check failing to see a tuple that definitely exists:
    ERROR:  insert or update on table "child_table" violates foreign key constraint "fk_constraint_name"
    DETAIL:  Key (keyid)=(123456) is not present in table "parent_table".
(where the key is observably present in the table).

Discussion: https://postgr.es/m/20170714210011.r25mrff4nxjhmf3g@alvherre.pgsql
2017-07-26 17:24:16 -04:00
Alvaro Herrera c28e4f4dc6 Remove obsolete comments about functional dependencies
Initial submitted versions of the functional dependencies patch ignored
row groups that were smaller than a configured size.  However, that
consideration was removed in late stages of the patch just before
commit, but some comments referring to it remained.  Remove them to
avoid confusion.

Author: Atsushi Torikoshi
Discussion: https://postgr.es/m/7cfb23fc-4493-9c02-5da9-e505fd0115d2@lab.ntt.co.jp
2017-07-26 11:40:39 -04:00
Alvaro Herrera 9915de6c1c Fix race conditions in replication slot operations
It is relatively easy to get a replication slot to look as still active
while one process is in the process of getting rid of it; when some
other process tries to "acquire" the slot, it would fail with an error
message of "replication slot XYZ is active for PID N".

The error message in itself is fine, except that when the intention is
to drop the slot, it is unhelpful: the useful behavior would be to wait
until the slot is no longer acquired, so that the drop can proceed.  To
implement this, we use a condition variable so that slot acquisition can
be told to wait on that condition variable if the slot is already
acquired, and we make any change in active_pid broadcast a signal on the
condition variable.  Thus, as soon as the slot is released, the drop
will proceed properly.

Reported by: Tom Lane
Discussion: https://postgr.es/m/11904.1499039688@sss.pgh.pa.us
Authors: Petr Jelínek, Álvaro Herrera
2017-07-25 13:26:49 -04:00
Robert Haas 4132dbec69 Fix partitioning crashes during error reporting.
In various places where we reverse-map a tuple before calling
ExecBuildSlotValueDescription, we neglected to ensure that the
slot descriptor matched the tuple stored in it.

Amit Langote and Amit Khandekar, reviewed by Etsuro Fujita

Discussion: http://postgr.es/m/CAJ3gD9cqpP=WvJj=dv1ONkPWjy8ZuUaOM4_x86i3uQPas=0_jg@mail.gmail.com
2017-07-24 18:08:08 -04:00