Merge pull request #44 from percona/improved-autovacuum-candiate

Improved query for getting candidate tables for autovacuum

Author: impimp

postgresql/autovacuum-candidate-table.sql

@@ -0,0 +1,40 @@
+WITH vbt AS (SELECT setting AS autovacuum_vacuum_threshold FROM 
+pg_settings WHERE name = 'autovacuum_vacuum_threshold')
+    , vsf AS (SELECT setting AS autovacuum_vacuum_scale_factor FROM 
+pg_settings WHERE name = 'autovacuum_vacuum_scale_factor')
+    , fma AS (SELECT setting AS autovacuum_freeze_max_age FROM 
+pg_settings WHERE name = 'autovacuum_freeze_max_age')
+    , sto AS (select opt_oid, split_part(setting, '=', 1) as param, 
+split_part(setting, '=', 2) as value from (select oid opt_oid, 
+unnest(reloptions) setting from pg_class) opt)
+SELECT
+    '"'||ns.nspname||'"."'||c.relname||'"' as relation
+    , pg_size_pretty(pg_table_size(c.oid)) as table_size
+    , age(relfrozenxid) as xid_age
+    , coalesce(cfma.value::float, autovacuum_freeze_max_age::float) 
+autovacuum_freeze_max_age
+    , (coalesce(cvbt.value::float, autovacuum_vacuum_threshold::float) 
++ coalesce(cvsf.value::float,autovacuum_vacuum_scale_factor::float) * 
+pg_table_size(c.oid)) as autovacuum_vacuum_tuples
+    , n_dead_tup as dead_tuples
+FROM pg_class c join pg_namespace ns on ns.oid = c.relnamespace
+join pg_stat_all_tables stat on stat.relid = c.oid
+join vbt on (1=1) join vsf on (1=1) join fma on (1=1)
+left join sto cvbt on cvbt.param = 'autovacuum_vacuum_threshold' and 
+c.oid = cvbt.opt_oid
+left join sto cvsf on cvsf.param = 'autovacuum_vacuum_scale_factor' and 
+c.oid = cvsf.opt_oid
+left join sto cfma on cfma.param = 'autovacuum_freeze_max_age' and 
+c.oid = cfma.opt_oid
+WHERE c.relkind = 'r' and nspname <> 'pg_catalog'
+and (
+    age(relfrozenxid) >= coalesce(cfma.value::float, 
+autovacuum_freeze_max_age::float)
+    or
+    coalesce(cvbt.value::float, autovacuum_vacuum_threshold::float) + 
+coalesce(cvsf.value::float,autovacuum_vacuum_scale_factor::float) * 
+pg_table_size(c.oid) <= n_dead_tup
+   -- or 1 = 1
+)
+ORDER BY age(relfrozenxid) DESC LIMIT 50;
+