Accept that we can't get versions for such locale names for now. Users
will need to specify the newer language tag format to enable the
collation versioning feature. It's not clear that we can do automatic
conversion from the old style to the new style reliably enough for this
purpose.
Unfortunately, this means that collation versioning probably won't work
for the default collation unless you provide something like en-US at
initdb or CREATE DATABASE time (though, for reasons not yet understood,
it does seem to work on some systems). It'd be nice to find a better
solution, or document this quirk if we settle on it, but this should
unbreak the 3 failing build farm animals in the meantime.
Reviewed-by: David Rowley <dgrowleyml@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CAEepm%3D0uEQCpfq_%2BLYFBdArCe4Ot98t1aR4eYiYTe%3DyavQygiQ%40mail.gmail.com
When considering Incremental Sort below a Gather Merge, we need to be
a bit more careful when matching pathkeys to EC members. It's not enough
to find a member whose Vars are all in the current relation's target;
volatile expressions in particular need to be contained in the target,
otherwise it's too early to use the pathkey.
Reported-by: Jaime Casanova
Author: James Coleman
Reviewed-by: Tomas Vondra
Backpatch-through: 13, where the incremental sort code was added
Discussion: https://postgr.es/m/CAJGNTeNaxpXgBVcRhJX%2B2vSbq%2BF2kJqGBcvompmpvXb7pq%2BoFA%40mail.gmail.com
If the planner erroneously puts a non-parallel-safe SubPlan into
a parallelized portion of the query tree, nodeSubplan.c will fail
in the worker processes because it finds a null in es_subplanstates,
which it's unable to cope with. It seems worth a test-and-elog to
make that an error case rather than a core dump case.
This probably should have been included in commit 16ebab688, which
was responsible for allowing nulls to appear in es_subplanstates
to begin with. So, back-patch to v10 where that came in.
Discussion: https://postgr.es/m/924226.1604422326@sss.pgh.pa.us
The intention in commit 491c029db was to require superuserness to
change the BYPASSRLS property, but the actual effect of the coding
in AlterRole() was to require superuserness to change anything at all
about a BYPASSRLS role. Other properties of a BYPASSRLS role should
be changeable under the same rules as for a normal role, though.
Fix that, and also take care of some documentation omissions related
to BYPASSRLS and REPLICATION role properties.
Tom Lane and Stephen Frost, per bug report from Wolfgang Walther.
Back-patch to all supported branches.
Discussion: https://postgr.es/m/a5548a9f-89ee-3167-129d-162b5985fcf8@technowledgy.de
The current implementation cannot handle this correctly, so just
forbid it for now.
GENERATED clauses must be attached to the column definition and cannot
be added later like DEFAULT, so if a child table has a generation
expression that the parent does not have, the child column will
necessarily be an attlocal column. So to implement ALTER TABLE ONLY /
DROP EXPRESSION, we'd need extra code to update attislocal of the
direct child tables, somewhat similar to how DROP COLUMN does it, so
that the resulting state can be properly dumped and restored.
Discussion: https://www.postgresql.org/message-id/flat/15830.1575468847%40sss.pgh.pa.us
Remove old containment operators @ and ~ for built-in geometry data
types. These have been deprecated; use <@ and @> instead.
(Some contrib modules still contain the same deprecated operators.
That will be dealt with separately.)
Author: Justin Pryzby <pryzby@telsasoft.com>
Discussion: https://www.postgresql.org/message-id/flat/20201027032511.GF9241@telsasoft.com
Commit 3a9ae3d206 (back in 2006) deprecated TG_RELNAME
in favor of TG_TABLE_NAME, but the existing usage in test
cases has remained till today. Change to use TG_TABLE_NAME
instead (TG_RELNAME is still covered by a test case).
Commit d94c36a45a introduced error handling to sslinfo to handle
OpenSSL errors gracefully. This ports this errorhandling to the
backend TLS implementation.
Author: Daniel Gustafsson <daniel@yesql.se>
sslinfo was passing the Port->ssl member directly to OpenSSL in order
to extract information regarding the connection. This breaks the API
provided by the backend TLS implementation, as well as duplicates code
for no benefit. Rewrite to make use of the backend API as much as
possible.
Author: Daniel Gustafsson <daniel@yesql.se>
fill_hba_line() thought it could get away with passing sizeof(struct
sockaddr_storage) rather than the actual addrlen previously returned
by getaddrinfo(). While that appears to work on many platforms,
it does not work on FreeBSD 11: you get back a failure, which leads
to the view showing NULL for the address and netmask columns in all
rows. The POSIX spec for getnameinfo() is pretty clearly on
FreeBSD's side here: you should pass the actual address length.
So it seems plausible that there are other platforms where this
coding also fails, and we just hadn't noticed.
Also, IMO the fact that getnameinfo() failure leads to a NULL output
is pretty bogus in itself. Our pg_getnameinfo_all() wrapper is
careful to emit "???" on failure, and we should use that in such
cases. NULL should only be emitted in rows that don't have IP
addresses.
Per bug #16695 from Peter Vandivier. Back-patch to v10 where this
code was added.
Discussion: https://postgr.es/m/16695-a665558e2f630be7@postgresql.org
make_ruledef() and make_viewdef() were coded to cope with possible
null-ness of these columns, but they've been marked BKI_FORCE_NOT_NULL
for some time. So there's not really any need to do more than what
we do for the other columns of pg_rewrite, i.e. just Assert that
we got non-null results.
(There is a school of thought that says Asserts aren't the thing
to do to check for corrupt data, but surely here is not the place
to start if we want such a policy.)
Also, remove long-dead-if-indeed-it-ever-wasn't-dead handling of
an empty actions list in make_ruledef(). That's an error case
and should be treated as such. (DO INSTEAD NOTHING is represented
by a CMD_NOTHING Query, not an empty list; cf transformRuleStmt.)
Kyotaro Horiguchi, some changes by me
Discussion: https://postgr.es/m/CAEudQApoA=tMTic6xEPYP_hsNZ8XtToVThK_0x7D_aFQYowq3w@mail.gmail.com
Traditionally, the names of fmgroids.h macros for pg_proc OIDs
have been constructed from the prosrc field. But sometimes the
same C function underlies multiple pg_proc entries, forcing us
to make an arbitrary choice of which OID to reference; the other
entries are then not namable via fmgroids.h. Moreover, we could
not have macros at all for pg_proc entries that aren't for
C-coded functions.
Instead, use the proname field, and append the proargtypes field
(replacing inter-argument spaces with underscores) if proname is
not unique. Special-casing unique entries such as F_OIDEQ removes
the need to change a lot of code. Indeed, I can only find two
places in the tree that need to be adjusted; while this changes
quite a few existing entries in fmgroids.h, few of them are
referenced from C code.
With this patch, all entries in pg_proc.dat have macros in fmgroids.h.
Discussion: https://postgr.es/m/472274.1604258384@sss.pgh.pa.us
On detecting a corrupted match tag, pglz_decompress() should just
summarily return -1. Breaking out of the loop, as I did in dfc797730,
doesn't quite guarantee that will happen. Also, we can use
unlikely() on that check, just in case it helps.
Backpatch to v13, like the previous patch.
Some places were using PG_GETARG_UINT32 where PG_GETARG_TRANSACTIONID
would be more appropriate. (Of course, they are the same internally,
so there is no externally visible effect.) To do that, export
PG_GETARG_TRANSACTIONID outside of xid.c. We also export
PG_RETURN_TRANSACTIONID for symmetry, even though there are currently
no external users.
Author: Ashutosh Bapat <ashutosh.bapat@2ndquadrant.com>
Discussion: https://www.postgresql.org/message-id/flat/d8f6bdd536df403b9b33816e9f7e0b9d@G08CNEXMBPEKD05.g08.fujitsu.local
Record the current version of dependent collations in pg_depend when
creating or rebuilding an index. When accessing the index later, warn
that the index may be corrupted if the current version doesn't match.
Thanks to Douglas Doole, Peter Eisentraut, Christoph Berg, Laurenz Albe,
Michael Paquier, Robert Haas, Tom Lane and others for very helpful
discussion.
Author: Thomas Munro <thomas.munro@gmail.com>
Author: Julien Rouhaud <rjuju123@gmail.com>
Reviewed-by: Peter Eisentraut <peter.eisentraut@2ndquadrant.com> (earlier versions)
Discussion: https://postgr.es/m/CAEepm%3D0uEQCpfq_%2BLYFBdArCe4Ot98t1aR4eYiYTe%3DyavQygiQ%40mail.gmail.com
Provide a place for the version of referenced database objects to be
recorded. A follow-up commit will use this to record dependencies on
collation versions for indexes, but similar ideas for other kinds of
objects have also been mooted.
Author: Thomas Munro <thomas.munro@gmail.com>
Reviewed-by: Julien Rouhaud <rjuju123@gmail.com>
Reviewed-by: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Discussion: https://postgr.es/m/CAEepm%3D0uEQCpfq_%2BLYFBdArCe4Ot98t1aR4eYiYTe%3DyavQygiQ%40mail.gmail.com
This model couldn't be extended to cover the default collation, and
didn't have any information about the affected database objects when the
version changed. Remove, in preparation for a follow-up commit that
will add a new mechanism.
Author: Thomas Munro <thomas.munro@gmail.com>
Reviewed-by: Julien Rouhaud <rjuju123@gmail.com>
Reviewed-by: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Discussion: https://postgr.es/m/CAEepm%3D0uEQCpfq_%2BLYFBdArCe4Ot98t1aR4eYiYTe%3DyavQygiQ%40mail.gmail.com
This was broken recently by a929e17e5. I'd failed to remember that
parallel tests should have their EXPLAIN output run through the
explain_parallel_append function so that the output is stable when
parallel workers fail to start.
fairywren was first to notice.
Reported-by: Michael Paquier
Discussion: https://postgr.es/m/20201102062951.GB15770@paquier.xyz
Logical replication protocol uses a single byte character to identify a
message type in logical replication protocol. The code uses string
literals for the same. Use Enum so that
1. All the string literals used can be found at a single place. This
makes it easy to add more types without the risk of conflicts.
2. It's easy to locate the code handling a given message type.
3. When used with switch statements, it is easy to identify the missing
cases using -Wswitch.
Author: Ashutosh Bapat
Reviewed-by: Kyotaro Horiguchi, Andres Freund, Peter Smith and Amit Kapila
Discussion: https://postgr.es/m/CAExHW5uPzQ7L0oAd_ENyvaiYMOPgkrAoJpE+ZY5-obdcVT6NPg@mail.gmail.com
Previously we only tagged on the required information to allow the
executor to perform run-time partition pruning for Append/MergeAppend
nodes belonging to base relations. It was thought that nested
Append/MergeAppend nodes were just about always pulled up into the
top-level Append/MergeAppend and that making the run-time pruning info for
any sub Append/MergeAppend nodes was a waste of time. However, that was
likely badly thought through.
Some examples of cases we're unable to pullup nested Append/MergeAppends
are: 1) Parallel Append nodes with a mix of parallel and non-parallel
paths into a Parallel Append. 2) When planning an ordered Append scan a
sub-partition which is unordered may require a nested MergeAppend path to
ensure sub-partitions don't mix up the order of tuples being fed into the
top-level Append.
Unfortunately, it was not just as simple as removing the lines in
createplan.c which were purposefully not building the run-time pruning
info for anything but RELOPT_BASEREL relations. The code in
add_paths_to_append_rel() was far too sloppy about which partitioned_rels
it included for the Append/MergeAppend paths. The original code there
would always assume accumulate_append_subpath() would pull each sub-Append
and sub-MergeAppend path into the top-level path. While it does not
appear that there were any actual bugs caused by having the additional
partitioned table RT indexes recorded, what it did mean is that later in
planning, when we built the run-time pruning info that we wasted effort
and built PartitionedRelPruneInfos for partitioned tables that we had no
subpaths for the executor to run-time prune.
Here we tighten that up so that partitioned_rels only ever contains the RT
index for partitioned tables which actually have subpaths in the given
Append/MergeAppend. We can now Assert that every PartitionedRelPruneInfo
has a non-empty present_parts. That should allow us to catch any weird
corner cases that have been missed.
In passing, it seems there is no longer a good reason to have the
AppendPath and MergeAppendPath's partitioned_rel fields a List of IntList.
We can simply have a List of Relids instead. This is more compact in
memory and faster to add new members to. We still know which is the root
level partition as these always have a lower relid than their children.
Previously this field was used for more things, but run-time partition
pruning now remains the only user of it and it has no need for a List of
IntLists.
Here we also get rid of the RelOptInfo partitioned_child_rels field. This
is what was previously used to (sometimes incorrectly) set the
Append/MergeAppend path's partitioned_rels field. That was the only usage
of that field, so we can happily just remove it.
I also couldn't resist changing some nearby code to make use of the newly
added for_each_from macro so we can skip the first element in the list
without checking if the current item was the first one on each
iteration.
A bug report from Andreas Kretschmer prompted all this work, however,
after some consideration, I'm not personally classing this as a bug fix.
So no backpatch. In Andreas' test case, it just wasn't that clear that
there was a nested Append since the top-level Append just had a single
sub-path which was pulled up a level, per 8edd0e794.
Author: David Rowley
Reviewed-by: Amit Langote
Discussion: https://postgr.es/m/flat/CAApHDvqSchs%2BubdybcfFaSPB%2B%2BEA7kqMaoqajtP0GtZvzOOR3g%40mail.gmail.com
pglz_maximum_compressed_size() potentially underestimated the amount
of compressed data required to produce N bytes of decompressed data;
this is a fault in commit 11a078cf8.
Separately from that, pglz_decompress() failed to protect itself
against corrupt compressed data, particularly off == 0 in a match
tag. Commit c60e520f6 turned such a situation into an infinite loop,
where before it'd just have resulted in garbage output.
The combination of these two bugs seems like it may explain bug #16694
from Tom Vijlbrief, though it's impossible to be quite sure without
direct inspection of the failing session. (One needs to assume that
the pglz_maximum_compressed_size() bug caused us to fail to fetch the
second byte of a match tag, and what happened to be there instead was
a zero. The reported infinite loop is hard to explain without off == 0,
though.)
Aside from fixing the bugs, rewrite associated comments for more
clarity.
Back-patch to v13 where both these commits landed.
Discussion: https://postgr.es/m/16694-f107871e499ec114@postgresql.org
Although error results received from the backend should always have
a SQLSTATE field, ones generated by libpq won't, making this code
vulnerable to a crash after, say, untimely loss of connection.
Noted by Coverity.
Oversight in commit 403a3d91c. Back-patch to 9.5, as that was.
Statistics associated to an index got lost after running REINDEX
CONCURRENTLY, while the non-concurrent case preserves these correctly.
The concurrent and non-concurrent operations need to be consistent for
the end-user, and missing statistics would force to wait for a new
analyze to happen, which could take some time depending on the activity
of the existing autovacuum workers. This issue is fixed by copying any
existing entries in pg_statistic associated to the old index to the new
one. Note that this copy is already done with the data of the index in
the stats collector.
Reported-by: Fabrízio de Royes Mello
Author: Michael Paquier, Fabrízio de Royes Mello
Reviewed-by: Justin Pryzby
Discussion: https://postgr.es/m/CAFcNs+qpFPmiHd1oTXvcPdvAHicJDA9qBUSujgAhUMJyUMb+SA@mail.gmail.com
Backpatch-through: 12
PXE_DECRYPT_FAILED exists already for decryption errors, and an
equivalent for encryption did not exist. There is one code path that
deals with such failures for OpenSSL but it used PXE_ERR_GENERIC, which
was inconsistent. This switches this code path to use the new error
PXE_ENCRYPT_FAILED instead of PXE_ERR_GENERIC, making the code used for
encryption more consistent with the decryption.
Author: Daniel Gustafsson
Discussion: https://postgr.es/m/03049139-CB7A-436E-B71B-42696D3E2EF7@yesql.se
Certain background workers initiate parallel queries while
debug_query_string==NULL, at which point they attempted strlen(NULL) and
died to SIGSEGV. Older debug_query_string observers allow NULL, so do
likewise in these newer ones. Back-patch to v11, where commit
7de4a1bcc5 introduced the first of these.
Discussion: https://postgr.es/m/20201014022636.GA1962668@rfd.leadboat.com
Because of this, if you tried to create an operator family with the new
sortsupport function, you got an error:
ERROR: support function number 11 is invalid for access method gist
We missed this in commit 16fa9b2b30 that added the sortsupport function,
because it only added sortsupport to a built-in operator family.
Author: Andrey Borodin
Discussion: https://www.postgresql.org/message-id/3520A18A-5C38-4697-A2E3-F3BDE3496CD5%40yandex-team.ru
The timetz test cases I added in commit a9632830b were unintentionally
sensitive to whether or not DST is active in the PST8PDT time zone.
Thus, they'll start failing this coming weekend, as reported by
Bernhard M. Wiedemann in bug #16689. Fortunately, DST-awareness is
not significant to the purpose of these test cases, so we can just
force them all to PDT (DST hours) to preserve stability of the
results.
Back-patch to v10, as the prior patch was.
Discussion: https://postgr.es/m/16689-57701daa23b377bf@postgresql.org
On the same reasoning as in commit 36b931214, forbid using custom
oid_symbol macros in pg_type as well as pg_proc, so that we always
rely on the predictable macro names generated by genbki.pl.
We do continue to grant grandfather status to the names CASHOID and
LSNOID, although those are now considered deprecated aliases for the
preferred names MONEYOID and PG_LSNOID. This is because there's
likely to be client-side code using the old names, and this bout of
neatnik-ism doesn't quite seem worth breaking client code.
There might be a case for grandfathering EVTTRIGGEROID, too, since
externally-maintained PLs may reference that symbol. But renaming
such references to EVENT_TRIGGEROID doesn't seem like a particularly
heavy lift --- we make far more significant backend API changes in
every major release. For now I didn't add that, but we could
reconsider if there's pushback.
The other names changed here seem pretty unlikely to have any outside
uses. Again, we could add alias macros if there are complaints, but
for now I didn't.
As before, no need for a catversion bump.
John Naylor
Discussion: https://postgr.es/m/CAFBsxsHpCbjfoddNGpnnnY5pHwckWfiYkMYSF74PmP1su0+ZOw@mail.gmail.com
When ComputeXidHorizons() was called before MyDatabaseOid is set,
e.g. because a dead row in a shared relation is encountered during
InitPostgres(), the horizon for normal tables was computed too
aggressively, ignoring all backends connected to a database.
During subsequent pruning in a data table the too aggressive horizon
could end up still being used, possibly leading to still needed tuples
being removed. Not good.
This is a bug in dc7420c2c9, which the test added in 94bc27b576 made
visible, if run with force_parallel_mode set to regress. In that case
the bug is reliably triggered, because "pruning_query" is run in a
parallel worker and the start of that parallel worker is likely to
encounter a dead row in pg_database.
The fix is trivial: Compute a more pessimistic data table horizon if
MyDatabaseId is not yet known.
Author: Andres Freund
Discussion: https://postgr.es/m/20201029040030.p4osrmaywhqaesd4@alap3.anarazel.de
This adds the statistics about transactions streamed to the decoding
output plugin from ReorderBuffer. Users can query the
pg_stat_replication_slots view to check these stats and call
pg_stat_reset_replication_slot to reset the stats of a particular slot.
Users can pass NULL in pg_stat_reset_replication_slot to reset stats of
all the slots.
Commit 9868167500 has added the basic infrastructure to capture the stats
of slot and this commit extends the statistics collector to track
additional information about slots.
Bump the catversion as we have added new columns in the catalog entry.
Author: Ajin Cherian and Amit Kapila
Reviewed-by: Sawada Masahiko and Dilip Kumar
Discussion: https://postgr.es/m/CAA4eK1+chpEomLzgSoky-D31qev19AmECNiEAietPQUGEFhtVA@mail.gmail.com
This fixes a bug in the edge case where, for a temp table, heap_page_prune()
can end up with a different horizon than heap_vacuum_rel(). Which can trigger
errors like "ERROR: cannot freeze committed xmax ...".
The bug was introduced due to interaction of a7212be8b9 "Set cutoff xmin more
aggressively when vacuuming a temporary table." with dc7420c2c9 "snapshot
scalability: Don't compute global horizons while building snapshots.".
The problem is caused by lazy_scan_heap() assuming that the only reason its
HeapTupleSatisfiesVacuum() call would return HEAPTUPLE_DEAD is if the tuple is
a HOT tuple, or if the tuple's inserting transaction has aborted since the
heap_page_prune() call. But after a7212be8b9 that was also possible in other
cases for temp tables, because heap_page_prune() uses a different visibility
test after dc7420c2c9.
The fix is fairly simple: Move the special case logic for temp tables from
vacuum_set_xid_limits() to the infrastructure introduced in dc7420c2c9. That
ensures that the horizon used for pruning is at least as aggressive as the one
used by lazy_scan_heap(). The concrete horizon used for temp tables is
slightly different than the logic in dc7420c2c9, but should always be as
aggressive as before (see comments).
A significant benefit to centralizing the logic procarray.c is that now the
more aggressive horizons for temp tables does not just apply to VACUUM but
also to e.g. HOT pruning and the nbtree killtuples logic.
Because isTopLevel is not needed by vacuum_set_xid_limits() anymore, I
undid the the related changes from a7212be8b9.
This commit also adds an isolation test ensuring that the more aggressive
vacuuming and pruning of temp tables keeps working.
Debugged-By: Amit Kapila <amit.kapila16@gmail.com>
Debugged-By: Tom Lane <tgl@sss.pgh.pa.us>
Debugged-By: Ashutosh Sharma <ashu.coek88@gmail.com>
Author: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/20201014203103.72oke6hqywcyhx7s@alap3.anarazel.de
Discussion: https://postgr.es/m/20201015083735.derdzysdtqdvxshp@alap3.anarazel.de
Commit f2b883969 did not get the memo about the new formatting
style for tables documenting built-in functions. I noticed because
of a PDF build warning about an overwidth table.
I started with the intention of just suppressing a PDF build warning
by removing the example output, but ended up doing more: correcting
factual errors in the function's signature, moving a bunch of
generalized handwaving into the "Using amcheck Effectively" section
which seemed a better place for it, and improving wording and markup
a little bit.
Discussion: https://postgr.es/m/732904.1603728748@sss.pgh.pa.us
In almost all other places, we use plain "r" or "w" mode in popen()
calls (the exceptions being for COPY data). This one has been
overlooked (possibly because it's buried in a ".l" flex file?),
but it's using PG_BINARY_R.
Kensuke Okamura complained in bug #16688 that we fail to strip \r
when stripping the trailing newline from a backtick result string.
That's true enough, but we'd also fail to convert embedded \r\n
cleanly, which also seems undesirable. Fixing the popen() mode
seems like the best way to deal with this.
It's been like this for a long time, so back-patch to all supported
branches.
Discussion: https://postgr.es/m/16688-c649c7b69cd7e6f8@postgresql.org
It's unsafe to do this at parse time because addition of generated
columns to a table would not invalidate stored rules containing
UPDATEs on the table ... but there might now be dependent generated
columns that were not there when the rule was made. This also fixes
an oversight that rewriteTargetView failed to update extraUpdatedCols
when transforming an UPDATE on an updatable view. (Since the new
calculation is downstream of that, rewriteTargetView doesn't actually
need to do anything; but before, there was a demonstrable bug there.)
In v13 and HEAD, this leads to easily-visible bugs because (since
commit c6679e4fc) we won't recalculate generated columns that aren't
listed in extraUpdatedCols. In v12 this bitmap is mostly just used
for trigger-firing decisions, so you'd only notice a problem if a
trigger cared whether a generated column had been updated.
I'd complained about this back in May, but then forgot about it
until bug #16671 from Michael Paul Killian revived the issue.
Back-patch to v12 where this field was introduced. If existing
stored rules contain any extraUpdatedCols values, they'll be
ignored because the rewriter will overwrite them, so the bug will
be fixed even for existing rules. (But note that if someone were
to update to 13.1 or 12.5, store some rules with UPDATEs on tables
having generated columns, and then downgrade to a prior minor version,
they might observe issues similar to what this patch fixes. That
seems unlikely enough to not be worth going to a lot of effort to fix.)
Discussion: https://postgr.es/m/10206.1588964727@sss.pgh.pa.us
Discussion: https://postgr.es/m/16671-2fa55851859fb166@postgresql.org
We have a perfectly good convention for OID macros for built-in functions
already, so making custom symbols is just introducing unnecessary
deviation from the convention. Remove the one case that had snuck in,
and add an error check in genbki.pl to discourage future instances.
Although this touches pg_proc.dat, there's no need for a catversion
bump since the actual catalog data isn't changed.
John Naylor
Discussion: https://postgr.es/m/CAFBsxsHpCbjfoddNGpnnnY5pHwckWfiYkMYSF74PmP1su0+ZOw@mail.gmail.com
get_foreign_key_join_selectivity() looks for join clauses that equate
the two sides of the FK constraint. However, if we have a query like
"WHERE fktab.a = pktab.a and fktab.a = 1", it won't find any such join
clause, because equivclass.c replaces the given clauses with "fktab.a
= 1 and pktab.a = 1", which can be enforced at the scan level, leaving
nothing to be done for column "a" at the join level.
We can fix that expectation without much trouble, but then a new problem
arises: applying the foreign-key-based selectivity rule produces a
rowcount underestimate, because we're effectively double-counting the
selectivity of the "fktab.a = 1" clause. So we have to cancel that
selectivity out of the estimate.
To fix, refactor process_implied_equality() so that it can pass back the
new RestrictInfo to its callers in equivclass.c, allowing the generated
"fktab.a = 1" clause to be saved in the EquivalenceClass's ec_derives
list. Then it's not much trouble to dig out the relevant RestrictInfo
when we need to adjust an FK selectivity estimate. (While at it, we
can also remove the expensive use of initialize_mergeclause_eclasses()
to set up the new RestrictInfo's left_ec and right_ec pointers.
The equivclass.c code can set those basically for free.)
This seems like clearly a bug fix, but I'm hesitant to back-patch it,
first because there's some API/ABI risk for extensions and second because
we're usually loath to destabilize plan choices in stable branches.
Per report from Sigrid Ehrenreich.
Discussion: https://postgr.es/m/1019549.1603770457@sss.pgh.pa.us
Discussion: https://postgr.es/m/AM6PR02MB5287A0ADD936C1FA80973E72AB190@AM6PR02MB5287.eurprd02.prod.outlook.com
Thomas Munro