pg_buffercache: Add pg_buffercache_relation_stats() function#36
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pg_buffercache: Add pg_buffercache_relation_stats() function#36
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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 due to the amount of buffer entries (one per page) this can be prohibitively expensive on large machines. 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 a lock whilst gathering its statistics. Author: Lukas Fittl <lukas@fittl.com> Reviewed by: Discussion:
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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 due to the amount of buffer entries (one per page) this can be prohibitively expensive on large machines. 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 a lock whilst gathering its statistics.