pg_buffercache: Add pg_buffercache_relations() function (v2)#50
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pg_buffercache: Add pg_buffercache_relations() function (v2)#50
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This function returns an aggregation of buffer contents, grouped on a per-relfilenode basis. This is often useful to understand which tables or indexes are currently in cache, and can show cache disruptions due to query activity when sampled over time. The existing pg_buffercache() function can be utilized for this by grouping the result, but passing a large amount of buffer entries (one per page) back to the tuplestore and then aggregating it can be prohibitively expensive with large buffer counts. Even on a small shared buffers (128MB) the new function is 10x faster. Similar to the existing summary functions this new function does not hold buffer partition or buffer header locks whilst gathering its statistics. Author: Lukas Fittl <lukas@fittl.com> Reviewed by: Jakub Wartak <jakub.wartak@enterprisedb.com> Reviewed by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com> Reviewed by: Haibo Yan <tristan.yim@gmail.com> Reviewed by: Masahiko Sawada <sawada.mshk@gmail.com> Reviewed by: Paul A Jungwirth <pj@illuminatedcomputing.com> Reviewed by: Khoa Nguyen <khoaduynguyen@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAP53Pkx0=ph0vG_M20yVAoK11yGSTZP=53-rZt36OCP4hBPaDQ@mail.gmail.com
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