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Tom Lane bfb69b1e5d Fix crash when logical decoding is invoked from a PL function.
The logical decoding functions do BeginInternalSubTransaction and
RollbackAndReleaseCurrentSubTransaction to clean up after themselves.
It turns out that AtEOSubXact_SPI has an unrecognized assumption that
we always need to cancel the active SPI operation in the SPI context
that surrounds the subtransaction (if there is one).  That's true
when the RollbackAndReleaseCurrentSubTransaction call is coming from
the SPI-using function itself, but not when it's happening inside
some unrelated function invoked by a SPI query.  In practice the
affected callers are the various PLs.

To fix, record the current subtransaction ID when we begin a SPI
operation, and clean up only if that ID is the subtransaction being
canceled.

Also, remove AtEOSubXact_SPI's assertion that it must have cleaned
up the surrounding SPI context's active tuptable.  That's proven
wrong by the same test case.

Also clarify (or, if you prefer, reinterpret) the calling conventions
for _SPI_begin_call and _SPI_end_call.  The memory context cleanup
in the latter means that these have always had the flavor of a matched
resource-management pair, but they weren't documented that way before.

Per report from Ben Chobot.

Back-patch to 9.4 where logical decoding came in.  In principle,
the SPI changes should go all the way back, since the problem dates
back to commit 7ec1c5a86.  But given the lack of field complaints
it seems few people are using internal subtransactions in this way.
So I don't feel a need to take any risks in 9.2/9.3.

Discussion: https://postgr.es/m/73FBA179-C68C-4540-9473-71E865408B15@silentmedia.com
2017-10-06 19:18:59 -04:00
config Absorb -D_USE_32BIT_TIME_T switch from Perl, if relevant. 2017-08-14 11:48:59 -04:00
contrib Fix crash when logical decoding is invoked from a PL function. 2017-10-06 19:18:59 -04:00
doc Don't recommend "DROP SCHEMA information_schema CASCADE". 2017-09-26 22:39:47 -07:00
src Fix crash when logical decoding is invoked from a PL function. 2017-10-06 19:18:59 -04:00
.dir-locals.el Update Emacs configuration 2013-08-13 20:08:44 -04:00
.gitattributes gitattributes: Ignore time zone data files for whitespace checks 2014-07-22 00:12:28 -04:00
.gitignore Add /config.cache to .gitignore in back branches 2017-02-25 13:04:22 -05:00
aclocal.m4 Remove cvs keywords from all files. 2010-09-20 22:08:53 +02:00
configure Avoid SIGBUS on Linux when a DSM memory request overruns tmpfs. 2017-09-25 16:09:20 -04:00
configure.in Avoid SIGBUS on Linux when a DSM memory request overruns tmpfs. 2017-09-25 16:09:20 -04:00
COPYRIGHT Update copyright for 2017 2017-01-03 12:37:53 -05:00
GNUmakefile.in Add TAP tests for client programs 2014-04-14 21:33:46 -04:00
HISTORY Change documentation references to PG website to use https: not http: 2017-05-20 21:50:47 -04:00
Makefile Allow make check in PL directories 2011-02-15 06:52:12 +02:00
README Change documentation references to PG website to use https: not http: 2017-05-20 21:50:47 -04:00
README.git Change documentation references to PG website to use https: not http: 2017-05-20 21:50:47 -04:00

PostgreSQL Database Management System
=====================================

This directory contains the source code distribution of the PostgreSQL
database management system.

PostgreSQL is an advanced object-relational database management system
that supports an extended subset of the SQL standard, including
transactions, foreign keys, subqueries, triggers, user-defined types
and functions.  This distribution also contains C language bindings.

PostgreSQL has many language interfaces, many of which are listed here:

	https://www.postgresql.org/download

See the file INSTALL for instructions on how to build and install
PostgreSQL.  That file also lists supported operating systems and
hardware platforms and contains information regarding any other
software packages that are required to build or run the PostgreSQL
system.  Copyright and license information can be found in the
file COPYRIGHT.  A comprehensive documentation set is included in this
distribution; it can be read as described in the installation
instructions.

The latest version of this software may be obtained at
https://www.postgresql.org/download/.  For more information look at our
web site located at https://www.postgresql.org/.