Re: [EXPLAIN] Nested loops

Could you provide the output of EXPLAIN ANALYZE with your query?

On Fri, Jan 9, 2009 at 7:06 PM, Reg Me Please <regmeplease(at)gmail(dot)com> wrote:
> Hi.
>
> For an INNER JOINed query, EXPLAIN says that a "nested loop" is responsible
> for the big part of the time needed to run.
>
> The 2 tables JOINed are:
>
> T1: multi-million rows
> T2: few dozens rows
>
> The join is though a single column in both sides and it's NOT a PK in either
> table. But I have indexes in both T1 and T2 for that column.
>
> I've read in the "Explaining EXPLAIN" by Rober Treat
> (at http://wiki.postgresql.org/wiki/Image:OSCON2005-ExplainingExplain.sxi)
> that this nested loop can be slow because of lacking of indexes.
>
> Is there any hint to try to speed that query up?
>
> As of now, only a REINDEX can help thanks to caching, I presume.
> But the EXPLAIN still says there's a slow nested loop.
>
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