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Alexander Korotkov dd951dc34a Prevent GIN deleted pages from being reclaimed too early
When GIN vacuum deletes a posting tree page, it assumes that no concurrent
searchers can access it, thanks to ginStepRight() locking two pages at once.
However, since 9.4 searches can skip parts of posting trees descending from the
root.  That leads to the risk that page is deleted and reclaimed before
concurrent search can access it.

This commit prevents the risk of above by waiting for every transaction, which
might wait to reference this page, to finish.  Due to binary compatibility
we can't change GinPageOpaqueData to store corresponding transaction id.
Instead we reuse page header pd_prune_xid field, which is unused in index pages.

Discussion: https://postgr.es/m/31a702a.14dd.166c1366ac1.Coremail.chjischj%40163.com
Author: Andrey Borodin, Alexander Korotkov
Reviewed-by: Alexander Korotkov
Backpatch-through: 9.4
2018-12-13 06:39:53 +03:00
config Postpone LLVM-related uses of AC_CHECK_DECLS. 2018-11-19 12:43:05 -05:00
contrib Repair bogus EPQ plans generated for postgres_fdw foreign joins. 2018-12-12 16:08:30 -05:00
doc Doc: improve documentation about ALTER LARGE OBJECT requirements. 2018-12-11 11:21:50 -05:00
src Prevent GIN deleted pages from being reclaimed too early 2018-12-13 06:39:53 +03:00
.dir-locals.el Update documentation editor setup instructions 2018-07-13 21:28:18 +02:00
.gitattributes Remove contrib/tsearch2. 2017-02-13 11:06:11 -05:00
.gitignore Support for optimizing and emitting code in LLVM JIT provider. 2018-03-22 11:05:22 -07:00
aclocal.m4 Fix configure's AC_CHECK_DECLS tests to work correctly with clang. 2018-11-19 12:01:47 -05:00
configure Postpone LLVM-related uses of AC_CHECK_DECLS. 2018-11-19 12:43:05 -05:00
configure.in Postpone LLVM-related uses of AC_CHECK_DECLS. 2018-11-19 12:43:05 -05:00
COPYRIGHT Update copyright for 2018 2018-01-02 23:30:12 -05:00
GNUmakefile.in Ensure we build generated headers at the start of some more cases. 2018-07-30 18:04:39 -04:00
HISTORY Change documentation references to PG website to use https: not http: 2017-05-20 21:50:47 -04:00
Makefile Fix non-GNU makefiles for AIX make. 2017-11-30 00:57:22 -08:00
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/.