CLOSE frees the resources associated with an open cursor. After the cursor is closed, no subsequent operations are allowed on it. A cursor should be closed when it is no longer needed.
Every non-holdable open cursor is implicitly closed when a transaction is terminated by COMMIT or ROLLBACK . A holdable cursor is implicitly closed if the transaction that created it aborts via ROLLBACK . If the creating transaction successfully commits, the holdable cursor remains open until an explicit CLOSE is executed, or the client disconnects.
PostgreSQL does not have an explicit OPEN cursor statement; a cursor is considered open when it is declared. Use the DECLARE statement to declare a cursor.
You can see all available cursors by querying the pg_cursors system view.