Tom Lane 7313cc0163 Improve contrib/pg_stat_statements to lump "similar" queries together. ... 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		2012-03-28 21:01:23 -04:00
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src	Improve contrib/pg_stat_statements to lump "similar" queries together.	2012-03-28 21:01:23 -04:00
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