I have a similar problem where my query is getting stuck for where long time. Some times it is getting completed in 30-35 mins and some times it is running for 5-6 days. This is happening from my application which is running on tomcat-5-5-33. If I try the same query from psql console this query gets completed in 30 sec to 1 minute. OS: Linux 5.8 - 64 bit Postgresql version: 8.4.7 The query is: SELECT encode(audit_history.history_id,'hex') from audit_history join (select config_state_id, max(compliance_audit_time) as enforcement_time from audit_history group by config_state_id)A on (audit_history.compliance_audit_time = A.enforcement_time AND audit_history.config_state_id = A.config_state_id) left join enforcement_trail on (audit_history.history_id = enforcement_trail.history_id) where enforcement_trail.history_id is null LIMIT 500; The query plan is: QUERY PLAN --------------------------------------------------------------------------------------------------------- -------------------------------------------------------------------------- Limit (cost=663730.68..765365.22 rows=1 width=17) -> Nested Loop Anti Join (cost=663730.68..765365.22 rows=1 width=17) -> Hash Join (cost=663730.68..765357.10 rows=1 width=17) Hash Cond: ((a.enforcement_time = mydb.audit_history.compliance_audit_time) AND (a.config_state_id = mydb.audit_history.config_state_id)) -> Subquery Scan a (cost=456217.60..471694.21 rows=28395 width=40) -> GroupAggregate (cost=456217.60..471410.26 rows=28395 width=25) -> Sort (cost=456217.60..461163.51 rows=1978363 width=25) Sort Key: mydb.audit_history.config_state_id -> Seq Scan on audit_history (cost=0.00..161415.63 rows=1978363 width=25) -> Hash (cost=161415.63..161415.63 rows=1978363 width=42) -> Seq Scan on audit_history (cost=0.00..161415.63 rows=1978363 width=42 ) -> Index Scan using cm_rpt_enforcment_trail_fkindex1 on enforcement_trail (cost=0.00..8.10 rows=1 width=17) Index Cond: (mydb.audit_history.history_id = enforcement_trail.history_id) This issue is happening only one customer setup and we don't see this issue in other linux setups. In general this query gets completed in seconds whether it is from tomcat or from psql console. The 'historyid' column is a bytearray which we are encoding with hex. I have tried reindxing both the tables used in the query but no luck. stract_output.txt <http://postgresql.1045698.n5.nabble.com/file/n5756437/stract_output.txt> Please let me know what is the issue here. -- View this message in context: http://postgresql.1045698.n5.nabble.com/Query-is-stuck-tp2093817p5756437.html Sent from the PostgreSQL - admin mailing list archive at Nabble.com. -- Sent via pgsql-admin mailing list (pgsql-admin@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin