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David Rowley ae1123f989 Overload index_form_tuple to allow the memory context to be supplied
40af10b57 changed things so we make use of a generation memory context for
storing tuples to be sorted by tuplesort.c. That change does not play
nicely with the changes made in 9f03ca915 (back in 2014). That commit
changed things so that index_form_tuple() is called while switched into
the tuplestore's tuplecontext. In order to fetch the tuple from the index,
index_form_tuple() must do various memory allocations which are unrelated
to the storage of the final returned tuple. Although all of these
allocations are pfree'd, the fact that we now use a generation context
means that the memory for these pfree'd allocations won't be used again by
any other allocation due to generation.c's lack of freelists.  This could
result in sorts used for building indexes exceeding maintenance_work_mem
by a very large amount.

Here we fix it so we no longer allocate anything apart from the tuple
itself into the generation context by adding a new version of
index_form_tuple named index_form_tuple_context, which can be called to
specify the MemoryContext to allocate the tuple into.

Discussion: https://postgr.es/m/CAApHDvrHQkiFRHiGiAS-LMOvJN-eK-s762=tVzBz8ZqUea-a_A@mail.gmail.com
Backpatch-through: 15, where 40af10b57 was added.
2022-07-07 08:14:32 +12:00
config Pre-beta mechanical code beautification. 2022-05-12 15:17:30 -04:00
contrib CREATE INDEX: use the original userid for more ACL checks. 2022-06-25 09:07:41 -07:00
doc relnotes: clarify that PG 15 multi-xid is advanced more 2022-07-05 14:06:45 -04:00
src Overload index_form_tuple to allow the memory context to be supplied 2022-07-07 08:14:32 +12:00
.cirrus.yml Make upgradecheck a no-op in MSVC's vcregress.pl 2022-04-02 12:06:11 +09:00
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GNUmakefile.in Run tests of libpq on installcheck-world, checkprep and check-world 2022-06-03 13:15:20 +09:00
HISTORY Canonicalize some URLs 2020-02-10 20:47:50 +01:00
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aclocal.m4 Probe $PROVE not $PERL while checking for modules needed by TAP tests. 2021-11-22 12:54:52 -05:00
configure Stamp 15beta2. 2022-06-27 16:11:56 -04:00
configure.ac Stamp 15beta2. 2022-06-27 16:11:56 -04:00

README

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/.