extended (pgstattuple) version for index/btree bloat estimation

Author: NikolayS

bloat/btree_pgstattuple.sql

@@ -0,0 +1,31 @@
+--https://github.com/dataegret/pg-utils/tree/master/sql
+--pgstattuple extension required
+--WARNING: without index name/mask query will read all available indexes which could cause I/O spikes
+with indexes as (
+    select * from pg_stat_user_indexes
+)
+select schemaname,
+table_name,
+pg_size_pretty(table_size) as table_size,
+index_name,
+pg_size_pretty(index_size) as index_size,
+idx_scan as index_scans,
+round((free_space*100/index_size)::numeric, 1) as waste_percent,
+pg_size_pretty(free_space) as waste
+from (
+    select schemaname, p.relname as table_name, indexrelname as index_name,
+    (select (case when avg_leaf_density = 'NaN' then 0 
+        else greatest(ceil(index_size * (1 - avg_leaf_density / (coalesce((SELECT (regexp_matches(reloptions::text, E'.*fillfactor=(\\d+).*'))[1]),'90')::real)))::bigint, 0) end)
+        from pgstatindex(schemaname || '.' || p.indexrelid::regclass::text)
+    ) as free_space,
+    pg_relation_size(p.indexrelid) as index_size,
+    pg_relation_size(p.relid) as table_size,
+    idx_scan
+    from indexes p
+    join pg_class c on p.indexrelid = c.oid
+    where pg_get_indexdef(p.indexrelid) like '%USING btree%' and
+    --put your index name/mask here
+    indexrelname ~ ''
+) t
+order by free_space desc;
+