Thank you BugsLaw for your interest. I've checked the select for only one table (TASK) earlier. I had pretty good results - 100k rows for about 3 seconds. And I was very surprised that after joining it with LOCATION perfromance dropped so much.
Here are the results with index: Starting transaction... Preparing statement: SELECT T.ID_TASK FROM TASK T WHERE T.IDSHEDULE IN (8169797) Statement prepared (elapsed time: 3.386s). Field #01: TASK.ID_TASK Alias:ID_TASK Type:INTEGER PLAN (T INDEX (IDX_TASK_IDSHEDULE)) Executing statement... Statement executed (elapsed time: 0.000s). 45747 fetches, 4 marks, 390 reads, 4 writes. 0 inserts, 0 updates, 0 deletes, 2704 index, 18924 seq. Delta memory: 53744 bytes. Total execution time: 3.760s Script execution finished. I have a copy of the database, but reactivating the index would take ages. I've recomputed all statistics and result for IDX_TASK_IDSHEDULE is 0.000004.
