The stats regression test attempts to ensure that Buffer Access Strategy "reuses" are being counted in pg_stat_io by vacuuming a table which is larger than the size of the strategy ring. However, when shared buffers are in sufficiently high demand, another backend could evict one of the blocks in the strategy ring before the first backend has a chance to reuse the buffer. The backend using the strategy would then evict another shared buffer and add that buffer to the strategy ring. This counts as an eviction and not a reuse in pg_stat_io. Count both evictions and reuses in the test to ensure it does not fail incorrectly. Reported-by: Jeff Davis <pgsql@j-davis.com>, Author: Melanie Plageman <melanieplageman@gmail.com> Reviewed-by: Alexander Lakhin <exclusion@gmail.com> Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com> Discussion: https://postgr.es/m/CAAKRu_bNG27AxG9TdPtwsL6wg8AWbVckjmTL2t1HF=miDQuNtw@mail.gmail.com |
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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/.