postgresql 查看tablespace命中率

?SELECT?a.datname,
???????pg_size_pretty(pg_database_size(a.datid))?AS?size,
???????CAST(blks_hit?/?(blks_read?+?blks_hit?+?0.000001)?*?100.0?AS
????????????NUMERIC(5,?2))?AS?cache,
???????CAST(xact_commit?/?(xact_rollback?+?xact_commit?+?0.000001)?*?100.0?AS
????????????NUMERIC(5,?2))?AS?success
??FROM?pg_stat_database?a
?ORDER?BY?pg_database_size(a.datid)?DESC;