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Get unused indices of your PostGIS database

Unused indices are the bane of your production database as even though they are unused, they have to be rebuild and cleaned along the lifetime of a table.

To quickly validate if the index you’ve created on design time are actually used at run time, you can simply use this handy little snipped to clean up your indices.

SELECT 	ui.schemaname,
       	ui.relname 		AS table_name,
       	ui.indexrelname 	AS index_name,
       	pg_relation_size(ui.indexrelid) AS index_size
FROM 	pg_catalog.pg_stat_user_indexes ui,
	pg_catalog.pg_index pi
WHERE 	ui.idx_scan = 0      -- has never been scanned
AND    	ui.indexrelid = pi.indexrelid  
AND 	0 <>ALL (pi.indkey)  -- no index column is an expression
AND NOT pi.indisunique   -- is not a UNIQUE index
AND NOT EXISTS          -- does not enforce a constraint
	FROM pg_catalog.pg_constraint pc
        WHERE pc.conindid = ui.indexrelid
ORDER BY table_name, pg_relation_size(ui.indexrelid) DESC

source: AWS

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