Re: 9.0 EXPLAIN Buffers: written=nnnn

El Thu, 2 Feb 2012 12:03:20 -0500
<david.sahagian@emc.com> escribió:
> Do EXPLAIN ANALYZE:
>
>   written=2325   !!!!!
>
> "Total runtime: 375542.347 ms"
>
>
> Then Do EXPLAIN ANALYZE again:

> In general, can you tell me why [written=2325] is displayed by the
> first EXPLAIN, but not the second EXPLAIN ? The query is a SELECT, so
> what is getting "written" ?
>
> Note that both EXPLAINs have the exact same plan. Bottom up is: Seq
> Scan on YYYY, Hash, Seq Scan on XXXX, Hash Join, HashAggregate
>
> I am wondering if it is a clue as to why the "actual time" is so
> different from one run to the next.
>

I can be completely wrong, but maybe it is about hint bits.

Read http://wiki.postgresql.org/wiki/Hint_Bits

Thanks

Rodrigo