Index analysis queries

index_analysis_content_indexes.sql

@@ -0,0 +1,89 @@
+-- Indexes in 'public' schema that are
+-- "content" indexes, i.e. they aren't system indexes
+-- for primary keys, unique constraints
+SELECT
+    n.nspname AS schema_name,
+    c.relname AS index_name,
+    t.relname AS table_name,
+    pg_index.indisunique AS is_unique,
+    pg_index.indisprimary AS is_primary
+FROM
+    pg_index
+    JOIN pg_class c ON c.oid = pg_index.indexrelid
+    JOIN pg_class t ON t.oid = pg_index.indrelid
+    JOIN pg_namespace n ON n.oid = t.relnamespace
+WHERE
+    n.nspname = 'public'
+    AND NOT pg_index.indisunique
+    AND NOT pg_index.indisprimary;
+
+
+-- Join to pg_constraint
+-- to exclude foreign key constraint indexes
+SELECT
+    n.nspname AS schema_name,
+    c.relname AS index_name,
+    t.relname AS table_name
+FROM
+    pg_index
+JOIN
+    pg_class c ON c.oid = pg_index.indexrelid
+JOIN
+    pg_class t ON t.oid = pg_index.indrelid
+JOIN
+    pg_namespace n ON n.oid = t.relnamespace
+LEFT JOIN
+    pg_constraint con ON con.conindid = pg_index.indexrelid
+WHERE
+    n.nspname = 'public'
+    AND NOT pg_index.indisprimary
+    AND con.contype IS NULL; -- Excludes indexes associated with constraints
+
+
+-- Find foreign key indexes
+-- Credit: https://mohyusufz.medium.com/how-to-check-for-indexes-on-foreign-key-columns-in-postgresql-450159772f8e
+WITH fk_constraints AS (
+    SELECT
+        c.conrelid::regclass AS table,
+        c.conname AS constraint,
+        string_agg(a.attname, ',' ORDER BY x.n) AS columns,
+        pg_catalog.pg_size_pretty(pg_catalog.pg_relation_size(c.conrelid)) AS size,
+        c.confrelid::regclass AS referenced_table,
+        c.conkey AS conkey,
+        c.conrelid AS conrelid
+    FROM
+        pg_catalog.pg_constraint c
+        /* Enumerated key column numbers per foreign key */
+        CROSS JOIN LATERAL unnest(c.conkey)
+        WITH ORDINALITY AS x (attnum, n)
+        /* Join to get the column names */
+        JOIN pg_catalog.pg_attribute a ON a.attnum = x.attnum
+            AND a.attrelid = c.conrelid
+    WHERE
+        /* Ensure the constraint is a foreign key */
+        c.contype = 'f'
+    GROUP BY
+        c.conrelid,
+        c.conname,
+        c.confrelid,
+        c.conkey
+)
+SELECT
+    fk.table,
+    fk.constraint,
+    fk.columns,
+    fk.size,
+    fk.referenced_table,
+    /* Retrieve the index name or mark as Unindexed */
+    COALESCE((
+        SELECT
+            i.indexrelid::regclass::text
+        FROM pg_catalog.pg_index i
+        WHERE
+            i.indrelid = fk.conrelid
+            AND i.indpred IS NULL
+            AND (i.indkey::smallint[])[0:cardinality(fk.conkey) - 1] OPERATOR (pg_catalog. @>) fk.conkey LIMIT 1), 'Unindexed') AS index_name
+FROM
+    fk_constraints fk
+ORDER BY
+    pg_catalog.pg_relation_size(fk.conrelid) DESC;