> Our Postgres recently started reporting considerably different > execution times for the same query. When executed from our JDBC > application the Postgres logs report an average execution time of 1500 > ms but when the query is manually executed through `psql` it doesn't > take longer than 50 ms.
I don't know why the plan is not saved by auto_explain (maybe we're missing ExecutorEnd calls somewhere? that would be strange), but one frequent reason for queries to show different plan in JDBC than psql is the use of prepared statements. Did you try using "PREPARE yourquery(...)" and then EXPLAIN EXECUTE(...)? Sometimes that helps to recreate the original problem.
(Apparently, ExecutorEnd is called from PortalCleanup; what happens with the portal for an extended-protocol query?)