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Alvaro Herrera 5804f4b39b Fix longstanding problems in VACUUM caused by untimely interruptions
In VACUUM FULL, an interrupt after the initial transaction has been recorded
as committed can cause postmaster to restart with the following error message:
PANIC: cannot abort transaction NNNN, it was already committed
This problem has been reported many times.

In lazy VACUUM, an interrupt after the table has been truncated by
lazy_truncate_heap causes other backends' relcache to still point to the
removed pages; this can cause future INSERT and UPDATE queries to error out
with the following error message:
could not read block XX of relation 1663/NNN/MMMM: read only 0 of 8192 bytes
The window to this race condition is extremely narrow, but it has been seen in
the wild involving a cancelled autovacuum process.

The solution for both problems is to inhibit interrupts in both operations
until after the respective transactions have been committed.  It's not a
complete solution, because the transaction could theoretically be aborted by
some other error, but at least fixes the most common causes of both problems.
2009-11-10 18:01:27 +00:00
config New version of mkinstalldirs fixes problems on Tru64 UNIX. 2005-01-08 09:54:29 +00:00
contrib Fix xslt_process() to ensure that it inserts a NULL terminator after the 2009-07-10 00:32:29 +00:00
doc Tag 8.0.22 2009-09-04 05:28:47 +00:00
src Fix longstanding problems in VACUUM caused by untimely interruptions 2009-11-10 18:01:27 +00:00
aclocal.m4 Add new auto-detection of thread flags. 2004-04-23 18:15:55 +00:00
configure Tag 8.0.22 2009-09-04 05:28:47 +00:00
configure.in Tag 8.0.22 2009-09-04 05:28:47 +00:00
COPYRIGHT Tag appropriate files for rc3 2004-12-31 22:04:05 +00:00
GNUmakefile.in Add installcheck-parallel target to top level makefiles. 2006-08-18 19:59:05 +00:00
Makefile Add installcheck-parallel target to top level makefiles. 2006-08-18 19:59:05 +00:00
README Remove more traces of libpgtcl from the source tree. Also, make some 2004-10-01 02:00:44 +00:00
README.CVS Some further editorializing on README.CVS. 2004-03-28 06:09:08 +00:00

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.

The JDBC, ODBC, C++, Python, and Tcl interfaces have been moved to the
PostgreSQL Projects Web Site at http://gborg.postgresql.org for separate
maintenance.  A Perl DBI/DBD driver is available from CPAN.

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
ftp://ftp.postgresql.org/pub/.  For more information look at our web
site located at http://www.postgresql.org/.