Allen,

> I had no idea analyze was playing such a big role in this sense.. I really
> thought that other than saving space, it wasn't doing much for tables that
> don't have indexes on the.

Among other things, ANALYZE tells postgres how many rows are in the table.  So 
if you add a PK constraint after loading 10 million rows without ANALYZE, 
PostgreSQL is likely to think that there is only one row in the table ... and 
choose a nested loop or some other really inefficient method of checking for 
uniqueness.

-- 
Josh Berkus
Aglio Database Solutions
San Francisco

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TIP 8: explain analyze is your friend

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