Table bloat SQL

Author: andyatkinson

table_bloat.sql

@@ -0,0 +1,66 @@
+-- Credit: https://github.com/ioguix/pgsql-bloat-estimation/tree/master/table
+-- minor tweaks to exclude pg tables
+/* WARNING: executed with a non-superuser role, the query inspect only tables and materialized view (9.3+) you are granted to read.
+* This query is compatible with PostgreSQL 9.0 and more
+*/
+SELECT current_database(), schemaname, tblname, bs*tblpages AS real_size,
+  (tblpages-est_tblpages)*bs AS extra_size,
+  CASE WHEN tblpages - est_tblpages > 0
+    THEN 100 * (tblpages - est_tblpages)/tblpages::float
+    ELSE 0
+  END AS extra_pct, fillfactor,
+  CASE WHEN tblpages - est_tblpages_ff > 0
+    THEN (tblpages-est_tblpages_ff)*bs
+    ELSE 0
+  END AS bloat_size,
+  CASE WHEN tblpages - est_tblpages_ff > 0
+    THEN 100 * (tblpages - est_tblpages_ff)/tblpages::float
+    ELSE 0
+  END AS bloat_pct, is_na
+  -- , tpl_hdr_size, tpl_data_size, (pst).free_percent + (pst).dead_tuple_percent AS real_frag -- (DEBUG INFO)
+FROM (
+  SELECT ceil( reltuples / ( (bs-page_hdr)/tpl_size ) ) + ceil( toasttuples / 4 ) AS est_tblpages,
+    ceil( reltuples / ( (bs-page_hdr)*fillfactor/(tpl_size*100) ) ) + ceil( toasttuples / 4 ) AS est_tblpages_ff,
+    tblpages, fillfactor, bs, tblid, schemaname, tblname, heappages, toastpages, is_na
+    -- , tpl_hdr_size, tpl_data_size, pgstattuple(tblid) AS pst -- (DEBUG INFO)
+  FROM (
+    SELECT
+      ( 4 + tpl_hdr_size + tpl_data_size + (2*ma)
+        - CASE WHEN tpl_hdr_size%ma = 0 THEN ma ELSE tpl_hdr_size%ma END
+        - CASE WHEN ceil(tpl_data_size)::int%ma = 0 THEN ma ELSE ceil(tpl_data_size)::int%ma END
+      ) AS tpl_size, bs - page_hdr AS size_per_block, (heappages + toastpages) AS tblpages, heappages,
+      toastpages, reltuples, toasttuples, bs, page_hdr, tblid, schemaname, tblname, fillfactor, is_na
+      -- , tpl_hdr_size, tpl_data_size
+    FROM (
+      SELECT
+        tbl.oid AS tblid, ns.nspname AS schemaname, tbl.relname AS tblname, tbl.reltuples,
+        tbl.relpages AS heappages, coalesce(toast.relpages, 0) AS toastpages,
+        coalesce(toast.reltuples, 0) AS toasttuples,
+        coalesce(substring(
+          array_to_string(tbl.reloptions, ' ')
+          FROM 'fillfactor=([0-9]+)')::smallint, 100) AS fillfactor,
+        current_setting('block_size')::numeric AS bs,
+        CASE WHEN version()~'mingw32' OR version()~'64-bit|x86_64|ppc64|ia64|amd64' THEN 8 ELSE 4 END AS ma,
+        24 AS page_hdr,
+        23 + CASE WHEN MAX(coalesce(s.null_frac,0)) > 0 THEN ( 7 + count(s.attname) ) / 8 ELSE 0::int END
+           + CASE WHEN bool_or(att.attname = 'oid' and att.attnum < 0) THEN 4 ELSE 0 END AS tpl_hdr_size,
+        sum( (1-coalesce(s.null_frac, 0)) * coalesce(s.avg_width, 0) ) AS tpl_data_size,
+        bool_or(att.atttypid = 'pg_catalog.name'::regtype)
+          OR sum(CASE WHEN att.attnum > 0 THEN 1 ELSE 0 END) <> count(s.attname) AS is_na
+      FROM pg_attribute AS att
+        JOIN pg_class AS tbl ON att.attrelid = tbl.oid
+        JOIN pg_namespace AS ns ON ns.oid = tbl.relnamespace
+        LEFT JOIN pg_stats AS s ON s.schemaname=ns.nspname
+          AND s.tablename = tbl.relname AND s.inherited=false AND s.attname=att.attname
+        LEFT JOIN pg_class AS toast ON tbl.reltoastrelid = toast.oid
+      WHERE NOT att.attisdropped
+        AND tbl.relname not like '%pg%'
+        AND tbl.relkind in ('r','m')
+      GROUP BY 1,2,3,4,5,6,7,8,9,10
+      ORDER BY 2,3
+    ) AS s
+  ) AS s2
+) AS s3
+-- WHERE NOT is_na
+--   AND tblpages*((pst).free_percent + (pst).dead_tuple_percent)::float4/100 >= 1
+ORDER BY bloat_pct DESC;