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Michael Paquier 8582b4d044 Improve handling of corrupted two-phase state files at recovery
When a corrupted two-phase state file is found by WAL replay, be it for
crash recovery or archive recovery, then the file is simply skipped and
a WARNING is logged to the user, causing the transaction to be silently
lost.  Facing an on-disk WAL file which is corrupted is as likely to
happen as what is stored in WAL records, but WAL records are already
able to fail hard if there is a CRC mismatch.  On-disk two-phase state
files, on the contrary, are simply ignored if corrupted.  Note that when
restoring the initial two-phase data state at recovery, files newer than
the horizon XID are discarded hence no files present in pg_twophase/
should be torned and have been made durable by a previous checkpoint, so
recovery should never see any corrupted two-phase state file by design.

The situation got better since 978b2f6 which has added two-phase state
information directly in WAL instead of using on-disk files, so the risk
is limited to two-phase transactions which live across at least one
checkpoint for long periods.  Backups having legit two-phase state files
on-disk could also lose silently transactions when restored if things
get corrupted.

This behavior exists since two-phase commit has been introduced, no
back-patch is done for now per the lack of complaints about this
problem.

Author: Michael Paquier
Discussion: https://postgr.es/m/20180709050309.GM1467@paquier.xyz
2018-09-07 11:00:16 -07:00
config Remove test for VA_ARGS, implied by C99. 2018-08-24 10:41:45 -07:00
contrib Make contrib/unaccent's unaccent() function work when not in search path. 2018-09-06 10:49:45 -04:00
doc Refactor installation of extension headers. 2018-09-07 14:19:14 +01:00
src Improve handling of corrupted two-phase state files at recovery 2018-09-07 11:00:16 -07:00
.dir-locals.el Update documentation editor setup instructions 2018-07-13 21:23:41 +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
COPYRIGHT Update copyright for 2018 2018-01-02 23:30:12 -05:00
GNUmakefile.in Remove unwanted "garbage cleanup" logic in Makefiles. 2018-08-08 14:32:29 -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
aclocal.m4 Add configure infrastructure (--with-llvm) to enable LLVM support. 2018-03-20 17:26:25 -07:00
configure Refactor dlopen() support 2018-09-06 11:33:04 +02:00
configure.in Refactor dlopen() support 2018-09-06 11:33:04 +02:00

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/.