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Tom Lane 2065dd2834 Prevent very-low-probability PANIC during PREPARE TRANSACTION. 
The code in PostPrepare_Locks supposed that it could reassign locks to
the prepared transaction's dummy PGPROC by deleting the PROCLOCK table
entries and immediately creating new ones.  This was safe when that code
was written, but since we invented partitioning of the shared lock table,
it's not safe --- another process could steal away the PROCLOCK entry in
the short interval when it's on the freelist.  Then, if we were otherwise
out of shared memory, PostPrepare_Locks would have to PANIC, since it's
too late to back out of the PREPARE at that point.

Fix by inventing a dynahash.c function to atomically update a hashtable
entry's key.  (This might possibly have other uses in future.)

This is an ancient bug that in principle we ought to back-patch, but the
odds of someone hitting it in the field seem really tiny, because (a) the
risk window is small, and (b) nobody runs servers with maxed-out lock
tables for long, because they'll be getting non-PANIC out-of-memory errors
anyway.  So fixing it in HEAD seems sufficient, at least until the new
code has gotten some testing.
 		2013-01-13 22:20:22 -05:00
config Improve handling of ereport(ERROR) and elog(ERROR). 2013-01-13 18:40:09 -05:00
contrib Improve handling of ereport(ERROR) and elog(ERROR). 2013-01-13 18:40:09 -05:00
doc Allow parallel copy/link in pg_upgrade 2013-01-09 08:57:47 -05:00
src Prevent very-low-probability PANIC during PREPARE TRANSACTION. 2013-01-13 22:20:22 -05:00
.gitignore Add gitignore for mingw/cygwin build outputs 2011-06-09 18:11:47 +02:00
COPYRIGHT Update copyrights for 2013 2013-01-01 17:15:01 -05:00
GNUmakefile.in Make init-po and update-po recursive make targets 2012-06-29 14:01:54 +03:00
Makefile Allow make check in PL directories 2011-02-15 06:52:12 +02:00
README Remove useless whitespace at end of lines 2010-11-23 22:34:55 +02:00
README.git Trivial typo fix. 2010-09-21 14:16:00 -04:00
aclocal.m4 Remove cvs keywords from all files. 2010-09-20 22:08:53 +02:00
configure Improve handling of ereport(ERROR) and elog(ERROR). 2013-01-13 18:40:09 -05:00
configure.in Improve handling of ereport(ERROR) and elog(ERROR). 2013-01-13 18:40:09 -05:00

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:

	http://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.  Changes between all PostgreSQL releases are recorded in the
file HISTORY.  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
http://www.postgresql.org/download/.  For more information look at our
web site located at http://www.postgresql.org/.