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4b203d499c
ba2a3c2302 has added a way to check if a buffer is spread across
multiple pages with some NUMA information, via a new view
pg_buffercache_numa that depends on pg_buffercache_numa_pages(), a SQL
function. These can only be queried when support for libnuma exists,
generating an error if not.
However, it can be useful to know how shared buffers and OS pages map
when NUMA is not supported or not available. This commit expands the
capabilities around pg_buffercache_numa:
- pg_buffercache_numa_pages() is refactored as an internal function,
able to optionally process NUMA. Its SQL definition prior to this
commit is still around to ensure backward-compatibility with v1.6.
- A SQL function called pg_buffercache_os_pages() is added, able to work
with or without NUMA.
- The view pg_buffercache_numa is redefined to use
pg_buffercache_os_pages().
- A new view is added, called pg_buffercache_os_pages. This ignores
NUMA for its result processing, for a better efficiency.
The implementation is done so as there is no code duplication between
the NUMA and non-NUMA views/functions, relying on one internal function
that does the job for all of them. The module is bumped to v1.7.
Author: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Reviewed-by: Mircea Cadariu <cadariu.mircea@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/Z/fFA2heH6lpSLlt@ip-10-97-1-34.eu-west-3.compute.internal
79 lines
2.7 KiB
SQL
79 lines
2.7 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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-- For pg_buffercache_os_pages, we expect at least one entry for each buffer
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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_os_pages;
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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_os_pages;
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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 count(*) > 0 FROM pg_buffercache_os_pages;
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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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