7313cc0163
pg_stat_statements now hashes selected fields of the analyzed parse tree to assign a "fingerprint" to each query, and groups all queries with the same fingerprint into a single entry in the pg_stat_statements view. In practice it is expected that queries with the same fingerprint will be equivalent except for values of literal constants. To make the display more useful, such constants are replaced by "?" in the displayed query strings. This mechanism currently supports only optimizable queries (SELECT, INSERT, UPDATE, DELETE). Utility commands are still matched on the basis of their literal query strings. There remain some open questions about how to deal with utility statements that contain optimizable queries (such as EXPLAIN and SELECT INTO) and how to deal with expiring speculative hashtable entries that are made to save the normalized form of a query string. However, fixing these issues should require only localized changes, and since there are other open patches involving contrib/pg_stat_statements, it seems best to go ahead and commit what we've got. Peter Geoghegan, reviewed by Daniel Farina |
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| README | ||
| README.git | ||
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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: 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/.