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Message Posted: Mon, 20 Jan 2004 @ 07:08:03 GMT
| Subj: || || Re: Query Optimization with Inner Joins |
| From: || || Hough, David A |
4) We execute the following steps in parallel.
1) We do an all-AMPs RETRIEVE step from DATABASE_1.temp by
way of an all-rows scan with a condition of ("(NOT
(DATABASE_1.temp.SCHEDULE_ID IS NULL )) AND (NOT
(DATABASE_1.temp.SESSION_ID IS NULL ))") into Spool 2
(all_amps), which is redistributed by hash code to all AMPs.
The size of Spool 2 is estimated with no confidence to be 114
rows. The estimated time for this step is 0.03 seconds.
This piece of the join plan is terrible. Try collecting stats on the PI for the small table and try to get the confidence above 'none'.
Also consider altering the index and join columns to 'NOT NULL'.