On Thu, 2005-08-25 at 12:24 -0700, Andrew Lazarus wrote:
> Should I temporarily increase sort_mem, vacuum_mem, neither, or both 
> when doing a CLUSTER on a large (100 million row) table where as many as 
> half of the tuples are deadwood from UPDATEs or DELETEs? I have large 
> batch (10 million row) inserts, updates, and deletes so I'm not sure 
> frequent vacuuming would help.

You may need to experiment with both. What version of Postgres? What is
the size of your database? How many concurrent users? If you're seeing
half of the tuples are dead, I look at checking your max_fsm_pages and
max_fsm_relations after a full vacuum analyze before doing too much with
sort mem.

Your mileage may vary.

Best of luck.

Steve Poe

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> TIP 5: don't forget to increase your free space map settings

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TIP 9: In versions below 8.0, the planner will ignore your desire to
       choose an index scan if your joining column's datatypes do not

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