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dcf7e1697b
In addition to the added functions, the pg_buffercache_evict() function now shows whether the buffer was flushed. pg_buffercache_evict_relation(): Evicts all shared buffers in a relation at once. pg_buffercache_evict_all(): Evicts all shared buffers at once. Both functions provide mechanism to evict multiple shared buffers at once. They are designed to address the inefficiency of repeatedly calling pg_buffercache_evict() for each individual buffer, which can be time-consuming when dealing with large shared buffer pools. (e.g., ~477ms vs. ~2576ms for 16GB of fully populated shared buffers). These functions are intended for developer testing and debugging purposes and are available to superusers only. Minimal tests for the new functions are included. Also, there was no test for pg_buffercache_evict(), test for this added too. No new extension version is needed, as it was already increased this release by ba2a3c2302f. Author: Nazir Bilal Yavuz <byavuz81@gmail.com> Reviewed-by: Andres Freund <andres@anarazel.de> Reviewed-by: Aidar Imamov <a.imamov@postgrespro.ru> Reviewed-by: Joseph Koshakow <koshy44@gmail.com> Discussion: https://postgr.es/m/CAN55FZ0h_YoSqqutxV6DES1RW8ig6wcA8CR9rJk358YRMxZFmw%40mail.gmail.com
71 lines
2.4 KiB
SQL
71 lines
2.4 KiB
SQL
CREATE EXTENSION pg_buffercache;
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select count(*) = (select setting::bigint
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from pg_settings
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where name = 'shared_buffers')
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from pg_buffercache;
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select buffers_used + buffers_unused > 0,
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buffers_dirty <= buffers_used,
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buffers_pinned <= buffers_used
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from pg_buffercache_summary();
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SELECT count(*) > 0 FROM pg_buffercache_usage_counts() WHERE buffers >= 0;
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-- Check that the functions / views can't be accessed by default. To avoid
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-- having to create a dedicated user, use the pg_database_owner pseudo-role.
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SET ROLE pg_database_owner;
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SELECT * FROM pg_buffercache;
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SELECT * FROM pg_buffercache_pages() AS p (wrong int);
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SELECT * FROM pg_buffercache_summary();
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SELECT * FROM pg_buffercache_usage_counts();
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RESET role;
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-- Check that pg_monitor is allowed to query view / function
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SET ROLE pg_monitor;
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SELECT count(*) > 0 FROM pg_buffercache;
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SELECT buffers_used + buffers_unused > 0 FROM pg_buffercache_summary();
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SELECT count(*) > 0 FROM pg_buffercache_usage_counts();
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RESET role;
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------
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---- Test pg_buffercache_evict* functions
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------
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CREATE ROLE regress_buffercache_normal;
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SET ROLE regress_buffercache_normal;
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-- These should fail because they need to be called as SUPERUSER
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SELECT * FROM pg_buffercache_evict(1);
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SELECT * FROM pg_buffercache_evict_relation(1);
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SELECT * FROM pg_buffercache_evict_all();
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RESET ROLE;
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-- These should return nothing, because these are STRICT functions
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SELECT * FROM pg_buffercache_evict(NULL);
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SELECT * FROM pg_buffercache_evict_relation(NULL);
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-- These should fail because they are not called by valid range of buffers
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-- Number of the shared buffers are limited by max integer
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SELECT 2147483647 max_buffers \gset
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SELECT * FROM pg_buffercache_evict(-1);
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SELECT * FROM pg_buffercache_evict(0);
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SELECT * FROM pg_buffercache_evict(:max_buffers);
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-- This should fail because pg_buffercache_evict_relation() doesn't accept
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-- local relations
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CREATE TEMP TABLE temp_pg_buffercache();
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SELECT * FROM pg_buffercache_evict_relation('temp_pg_buffercache');
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DROP TABLE temp_pg_buffercache;
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-- These shouldn't fail
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SELECT buffer_evicted IS NOT NULL FROM pg_buffercache_evict(1);
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SELECT buffers_evicted IS NOT NULL FROM pg_buffercache_evict_all();
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CREATE TABLE shared_pg_buffercache();
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SELECT buffers_evicted IS NOT NULL FROM pg_buffercache_evict_relation('shared_pg_buffercache');
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DROP TABLE shared_pg_buffercache;
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DROP ROLE regress_buffercache_normal;
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