e2c79e14d9
Previously, ginInsertCleanup could exit early if it detects that someone else is cleaning up the pending list, without waiting for that someone else to finish the job. But in this case vacuum could miss tuples to be deleted. Cleanup process now locks metapage with a help of heavyweight LockPage(ExclusiveLock), and it guarantees that there is no another cleanup process at the same time. Lock is taken differently depending on caller of cleanup process: any vacuums and gin_clean_pending_list() will be blocked until lock becomes available, ordinary insert uses conditional lock to prevent indefinite waiting on lock. Insert into pending list doesn't use this lock, so insertion isn't blocked. Also, patch adds stopping of cleanup process when at-start-cleanup-tail is reached in order to prevent infinite cleanup in case of massive insertion. But it will stop only for automatic maintenance tasks like autovacuum. Patch introduces choice of limit of memory to use: autovacuum_work_mem, maintenance_work_mem or work_mem depending on call path. Patch for previous releases should be reworked due to changes between 9.6 and previous ones in this area. Discover and diagnostics by Jeff Janes and Tomas Vondra Patch by me with some ideas of Jeff Janes
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. 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/.