Re: Unexpected sequence scan

Hi Tom, Kevin,

>> I have a query which is running slowly, and the query plan shows an
> unexpected sequence scan where I'd have expected the planner to use an
> index. Setting enable_seqscan=off causes the planner to use the index as
> expected.
>
> That hashjoin plan doesn't look at all unreasonable to me. The fact
> that it actually comes out a lot slower than the nestloop with inner
> indexscan suggests that you must be running with the large table
> completely cached in RAM. If that's the normal state of affairs for your
> database, you should consider decreasing the random_page_cost setting
> so that the planner will plan appropriately.
>

A very quick test of the settings that Kevin posted produce a much better plan and faster response to that query (at least on my dev machine) I'll read up more on those settings before changing production, but it looks good - thanks very much!

Cheers,
Dan
--
Dan Fairs | dan(dot)fairs(at)gmail(dot)com | www.fezconsulting.com