Created
February 10, 2018 01:16
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Postgres Table and Index cache hits and percentages
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with | |
all_tables as | |
( | |
SELECT * | |
FROM ( | |
SELECT 'all'::text as table_name, | |
sum( (coalesce(heap_blks_read,0) + coalesce(idx_blks_read,0) + coalesce(toast_blks_read,0) + coalesce(tidx_blks_read,0)) ) as from_disk, | |
sum( (coalesce(heap_blks_hit,0) + coalesce(idx_blks_hit,0) + coalesce(toast_blks_hit,0) + coalesce(tidx_blks_hit,0)) ) as from_cache | |
FROM pg_statio_all_tables --> change to pg_statio_USER_tables if you want to check only user tables (excluding postgres's own tables) | |
) a | |
WHERE (from_disk + from_cache) > 0 -- discard tables without hits | |
), | |
tables as | |
( | |
SELECT * | |
FROM ( | |
SELECT relname as table_name, | |
( (coalesce(heap_blks_read,0) + coalesce(idx_blks_read,0) + coalesce(toast_blks_read,0) + coalesce(tidx_blks_read,0)) ) as from_disk, | |
( (coalesce(heap_blks_hit,0) + coalesce(idx_blks_hit,0) + coalesce(toast_blks_hit,0) + coalesce(tidx_blks_hit,0)) ) as from_cache | |
FROM pg_statio_all_tables --> change to pg_statio_USER_tables if you want to check only user tables (excluding postgres's own tables) | |
) a | |
WHERE (from_disk + from_cache) > 0 -- discard tables without hits | |
) | |
SELECT table_name as "table name", | |
from_disk as "disk hits", | |
round((from_disk::numeric / (from_disk + from_cache)::numeric)*100.0,2) as "% disk hits", | |
round((from_cache::numeric / (from_disk + from_cache)::numeric)*100.0,2) as "% cache hits", | |
(from_disk + from_cache) as "total hits" | |
FROM (SELECT * FROM all_tables UNION ALL SELECT * FROM tables) a | |
ORDER BY (case when table_name = 'all' then 0 else 1 end), "disk hits" desc; |
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