postgresql/src/backend
Tom Lane e83a8ae447 Don't use a tuplestore if we don't have to for SQL-language functions.
We only need a tuplestore if we're actually going to accumulate
multiple result tuples.  Obviously then we don't need one for non-set-
returning functions; but even a SRF doesn't need one if we decide to
use "lazyEval" (one row at a time) mode.  In these cases, it's
sufficient to use the junkfilter's result slot to hold the single row
that's due to be returned.  We just need to "materialize" that slot
to ensure it holds onto the data past shutdown of the sub-executor.

The original intent of this patch was partially to save a few cycles
(by not putting tuples into a tuplestore only to pull them back out
immediately), but mostly to ensure that we don't use a tuplestore
in non-set-returning functions.  That's because I had concerns
about whether a tuplestore is safe to keep across queries,
which was possible for functions invoked via long-lived FmgrInfos
such as those kept in the typcache.  There are no cases where SRFs
are called that way, so getting rid of the tuplestore in non-SRFs
should make things safer.

However, it emerges that running fmgr_sql in a short-lived context
(as 595d1efed made it do) makes the existing coding unsafe anyway:
we can end up with a long-lived TupleTableSlot holding a freeable
reference to a short-lived tuple, resulting in a double-free crash.
Not trying to pull tuples out of the tuplestore using that slot
dodges the problem, so I'm going to commit this now rather than
invent a band-aid solution for v18.

Reported-by: Alexander Lakhin <exclusion@gmail.com>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/2443532.1744919968@sss.pgh.pa.us
Discussion: https://postgr.es/m/9f975803-1a1c-4f21-b987-f572e110e860@gmail.com
2025-05-02 16:16:20 -04:00
..
access Adjust overstrong nbtree skip array assertion. 2025-04-30 23:15:51 -04:00
archive Update copyright for 2025 2025-01-01 11:21:55 -05:00
backup Use XLOG_CONTROL_FILE macro consistently for control file name. 2025-04-07 09:27:33 +09:00
bootstrap Remove unnecessary (char *) casts [mem] 2025-02-12 08:50:13 +01:00
catalog Change the names generated for child foreign key constraints. 2025-04-23 12:03:02 -04:00
commands Handle self-referencing FKs correctly in partitioned tables 2025-05-02 21:25:50 +02:00
executor Don't use a tuplestore if we don't have to for SQL-language functions. 2025-05-02 16:16:20 -04:00
foreign Update copyright for 2025 2025-01-01 11:21:55 -05:00
jit Don't use double-quotes in #include's of system headers, redux. 2025-04-27 13:23:19 -04:00
lib Update copyright for 2025 2025-01-01 11:21:55 -05:00
libpq Modularize log_connections output 2025-03-12 11:35:21 -04:00
main Use thread-safe strftime_l() instead of strftime(). 2025-03-28 07:13:43 +01:00
nodes gen_node_support.pl: improve error message for unclosed struct. 2025-04-22 13:56:31 -04:00
optimizer Disallow removing placeholders during Self-Join Elimination. 2025-04-28 01:40:42 +03:00
parser Allow NOT NULL constraints to be added as NOT VALID 2025-04-07 19:19:50 +02:00
partitioning Fix bug in cbc127917 to handle nested Append correctly 2025-02-25 09:24:42 +09:00
po Update copyright for 2025 2025-01-01 11:21:55 -05:00
port Give up on running with NetBSD/OpenBSD's default semaphore settings. 2025-04-29 17:27:52 -04:00
postmaster Fix typos and grammar in the code 2025-04-19 19:17:42 +09:00
regex Another unintentional behavior change in commit e9931bfb75. 2025-04-16 16:49:42 -07:00
replication Fix assertion failure during decoding from synced slots. 2025-04-29 12:52:05 +05:30
rewrite Fixes for ChangeVarNodes_walker() 2025-04-29 14:34:44 +03:00
snowball Use PG_MODULE_MAGIC_EXT in our installable shared libraries. 2025-03-26 11:11:02 -04:00
statistics Fix recently introduced typos 2025-04-11 22:17:12 +02:00
storage Don't use double-quotes in #include's of system headers, redux. 2025-04-27 13:23:19 -04:00
tcop Add function to get memory context stats for processes 2025-04-08 11:06:56 +02:00
tsearch Clear errno before calling strtol() in spell.c. 2025-03-08 11:24:25 -05:00
utils Convert strncpy to strlcpy 2025-04-30 23:00:47 +02:00
.gitignore
common.mk Blind attempt to fix LLVM dependency in the backend 2022-09-15 10:53:48 +07:00
Makefile aio: Add liburing dependency 2025-03-26 19:45:32 -04:00
meson.build Update copyright for 2025 2025-01-01 11:21:55 -05:00
nls.mk Return yyparse() result not via global variable 2025-01-24 06:55:39 +01:00