Re: Planning large IN lists

Is this a TODO?

---------------------------------------------------------------------------

Tom Lane wrote:
> Neil Conway <neilc@samurai.com> writes:
> > When planning queries with a large IN expression in the WHERE clause,
> > the planner transforms the IN list into a scalar array expression. In
> > clause_selectivity(), we estimate the selectivity of the ScalarArrayExpr
> > by calling scalararraysel(), which in turn estimates the selectivity of
> > *each* array element in order to determine the selectivity of the array
> > expression as a whole.
> 
> > This is quite inefficient when the IN list is large.
> 
> That's the least of the problems.  We really ought to convert such cases
> into an IN (VALUES(...)) type of query, since often repeated indexscans
> aren't the best implementation.
> 
>             regards, tom lane
> 
> ---------------------------(end of broadcast)---------------------------
> TIP 7: You can help support the PostgreSQL project by donating at
> 
>                 http://www.postgresql.org/about/donate

--  Bruce Momjian  <bruce@momjian.us>          http://momjian.us EnterpriseDB
http://www.enterprisedb.com
 + If your life is a hard drive, Christ can be your backup. +