Re: Why does it not use the index?

Doug McNaught wrote:
> It's not the VACUUM that's necessary; it's the ANALYZE. The query
> planner uses table statistics to make its decisions, and ANALYZE is
> what collects those statistics. Without an ANALYZE the planner will
> make default assumptions that are rarely correct. :)

I am not the original poster, but I am a PG newbie, so:

So - are you saying that if you have a table, and you create an index on
that table, you need to perform an ANALYZE in order for PG to use the
index. Otherwise, the index goes unused (or used improperly)?

I am just trying to understand this for a database I have set up, where
I set up a variety of indexes, assumming (wrongly?) that the indexes
would be used once they were created.

Andrew L. Ayers
Phoenix, Arizona

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