28cac71bd3
There's a number of SLRU caches used to access important data like clog, commit timestamps, multixact, asynchronous notifications, etc. Until now we had no easy way to monitor these shared caches, compute hit ratios, number of reads/writes etc. This commit extends the statistics collector to track this information for a predefined list of SLRUs, and also introduces a new system view pg_stat_slru displaying the data. The list of built-in SLRUs is fixed, but additional SLRUs may be defined in extensions. Unfortunately, there's no suitable registry of SLRUs, so this patch simply defines a fixed list of SLRUs with entries for the built-in ones and one entry for all additional SLRUs. Extensions adding their own SLRU are fairly rare, so this seems acceptable. This patch only allows monitoring of SLRUs, not tuning. The SLRU sizes are still fixed (hard-coded in the code) and it's not entirely clear which of the SLRUs might need a GUC to tune size. In a way, allowing us to determine that is one of the goals of this patch. Bump catversion as the patch introduces new functions and system view. Author: Tomas Vondra Reviewed-by: Alvaro Herrera Discussion: https://www.postgresql.org/message-id/flat/20200119143707.gyinppnigokesjok@development |
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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/.