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Patch b19e4250b45e91c9cbdd18d35ea6391ab5961c8d attempted to preserve existing behavior regarding statistics generation in the case that a truncation attempt was canceled due to lock conflicts. It failed to do this accurately in two regards: (1) autovacuum had previously generated statistics if the truncate attempt failed to initially get the lock rather than having started the attempt, and (2) the VACUUM ANALYZE command had always generated statistics. Both of these changes were unintended, and are reverted by this patch. On review, there seems to be consensus that the previous failure to generate statistics when the truncate was terminated was more an unfortunate consequence of how that effort was previously terminated than a feature we want to keep; so this patch generates statistics even when an autovacuum truncation attempt terminates early. Another unintended change which is kept on the basis that it is an improvement is that when a VACUUM command is truncating, it will the new heuristic for avoiding blocking other processes, rather than keeping an AccessExclusiveLock on the table for however long the truncation takes. Per multiple reports, with some renaming per patch by Jeff Janes. Backpatch to 9.0, where problem was created.
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/.