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It was pointed out that pg_buffercache_summary()'s report of the overall average usage count isn't that useful, and what would be more helpful in many cases is to report totals for each possible usage count. Add a new function to do it like that. Since pg_buffercache 1.4 is already new for v16, we don't need to create a new extension version; we'll just define this as part of 1.4. Nathan Bossart Discussion: https://postgr.es/m/20230130233040.GA2800702@nathanxps13
58 lines
1.5 KiB
Plaintext
58 lines
1.5 KiB
Plaintext
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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?column?
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----------
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t
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(1 row)
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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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?column? | ?column? | ?column?
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----------+----------+----------
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t | t | t
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(1 row)
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SELECT count(*) > 0 FROM pg_buffercache_usage_counts() WHERE buffers >= 0;
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?column?
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----------
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t
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(1 row)
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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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ERROR: permission denied for view pg_buffercache
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SELECT * FROM pg_buffercache_pages() AS p (wrong int);
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ERROR: permission denied for function pg_buffercache_pages
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SELECT * FROM pg_buffercache_summary();
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ERROR: permission denied for function pg_buffercache_summary
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SELECT * FROM pg_buffercache_usage_counts();
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ERROR: permission denied for function 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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?column?
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----------
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t
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(1 row)
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SELECT buffers_used + buffers_unused > 0 FROM pg_buffercache_summary();
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?column?
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----------
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t
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(1 row)
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SELECT count(*) > 0 FROM pg_buffercache_usage_counts();
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?column?
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----------
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t
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(1 row)
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