From 55d8d4f14dbe130ffb3e0b60a2ccecb56d4d96ab Mon Sep 17 00:00:00 2001
From: jsmith <publicjs@tutanota.com>
Date: Wed, 4 May 2022 14:56:55 +0000
Subject: [PATCH] Add 'PostgreSQL/monitoring/bloat.sql'

---
 PostgreSQL/monitoring/bloat.sql | 47 +++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 PostgreSQL/monitoring/bloat.sql

diff --git a/PostgreSQL/monitoring/bloat.sql b/PostgreSQL/monitoring/bloat.sql
new file mode 100644
index 0000000..b0f7fb0
--- /dev/null
+++ b/PostgreSQL/monitoring/bloat.sql
@@ -0,0 +1,47 @@
+with foo as (
+  SELECT
+    schemaname, tablename, hdr, ma, bs,
+    SUM((1-null_frac)*avg_width) AS datawidth,
+    MAX(null_frac) AS maxfracsum,
+    hdr+(
+      SELECT 1+COUNT(*)/8
+      FROM pg_stats s2
+      WHERE null_frac<>0 AND s2.schemaname = s.schemaname AND s2.tablename = s.tablename
+    ) AS nullhdr
+  FROM pg_stats s, (
+    SELECT
+      (SELECT current_setting('block_size')::NUMERIC) AS bs,
+      CASE WHEN SUBSTRING(v,12,3) IN ('8.0','8.1','8.2') THEN 27 ELSE 23 END AS hdr,
+      CASE WHEN v ~ 'mingw32' THEN 8 ELSE 4 END AS ma
+    FROM (SELECT version() AS v) AS foo
+  ) AS constants
+  GROUP BY 1,2,3,4,5  
+), rs as (
+  SELECT
+    ma,bs,schemaname,tablename,
+    (datawidth+(hdr+ma-(CASE WHEN hdr%ma=0 THEN ma ELSE hdr%ma END)))::NUMERIC AS datahdr,
+    (maxfracsum*(nullhdr+ma-(CASE WHEN nullhdr%ma=0 THEN ma ELSE nullhdr%ma END))) AS nullhdr2
+  FROM foo  
+), sml as (
+  SELECT
+    schemaname, tablename, cc.reltuples, cc.relpages, bs,
+    CEIL((cc.reltuples*((datahdr+ma-
+      (CASE WHEN datahdr%ma=0 THEN ma ELSE datahdr%ma END))+nullhdr2+4))/(bs-20::FLOAT)) AS otta,
+    COALESCE(c2.relname,'?') AS iname, COALESCE(c2.reltuples,0) AS ituples, COALESCE(c2.relpages,0) AS ipages,
+    COALESCE(CEIL((c2.reltuples*(datahdr-12))/(bs-20::FLOAT)),0) AS iotta -- very rough approximation, assumes all cols
+  FROM rs
+  JOIN pg_class cc ON cc.relname = rs.tablename
+  JOIN pg_namespace nn ON cc.relnamespace = nn.oid AND nn.nspname = rs.schemaname AND nn.nspname <> 'information_schema'
+  LEFT JOIN pg_index i ON indrelid = cc.oid
+  LEFT JOIN pg_class c2 ON c2.oid = i.indexrelid
+)
+
+SELECT
+  current_database(), schemaname, tablename, /*reltuples::bigint, relpages::bigint, otta,*/
+  ROUND((CASE WHEN otta=0 THEN 0.0 ELSE sml.relpages::FLOAT/otta END)::NUMERIC,1) AS tbloat,
+  CASE WHEN relpages < otta THEN 0 ELSE bs*(sml.relpages-otta)::BIGINT END AS wastedbytes,
+  iname, /*ituples::bigint, ipages::bigint, iotta,*/
+  ROUND((CASE WHEN iotta=0 OR ipages=0 THEN 0.0 ELSE ipages::FLOAT/iotta END)::NUMERIC,1) AS ibloat,
+  CASE WHEN ipages < iotta THEN 0 ELSE bs*(ipages-iotta) END AS wastedibytes
+FROM sml
+ORDER BY wastedbytes DESC