Re: how to tune this query. - Mailing list pgsql-performance

I don't think indexes are going to help you here - with the FULL OUTER
JOINs, the query will have to look at and include each row from each
table you query from anyway, so it's going to choose sequential scans.
In addition, some of the lower join conditions are going to take forever.

What's is your goal?  The volume of data that I imagine this query would
produce can't possibly be useful. I'm guessing at the very least you'll
want to LEFT OUTER JOIN everything back against STG_Property, and leave
the other join conditions out of each ON statement.

Luckys wrote:

> Hi all,
> I got this query, I'm having indexes for PropertyId and Dates columns
> across all the tables, but still it takes ages to get me the result.
> What indexes would be proposed on this, or I'm helpless?
>
> FROM  STG_Property a
>
>   FULL OUTER JOIN
>     STG_PropConfirmedLogs b
>     ON (a.PropertyId = b.PropertyId AND a.p_LastModified =
> b.p_Modified_Date)
>
>   FULL OUTER JOIN
>     STG_PropConnectionFeesLogs c
>     ON ((a.PropertyId = c.PropertyId AND a.p_LastModified = c.p_ChangedOn)
>     OR  (b.PropertyId = c.PropertyId AND b.p_Modified_Date =
> c.p_ChangedOn))
>
>   FULL OUTER JOIN
>     STG_PropDeletedLogs d
>     ON ((a.PropertyId = d.PropertyId AND a.p_LastModified = d.p_DeletedOn)
>     OR  (b.PropertyId = d.PropertyId AND b.p_Modified_Date =
> d.p_DeletedOn)
>     OR  ( c.PropertyId = d.PropertyId AND c.p_ChangedOn = d.p_DeletedOn))
>
>   FULL OUTER JOIN
>     STG_PropFEWALogs e
>     ON ((a.PropertyId = e.PropertyId AND a.p_LastModified =
> e.p_Modified_Date)
>     OR  (b.PropertyId = e.PropertyId AND b.p_Modified_Date =
> e.p_Modified_Date) OR  (c.PropertyId = e.PropertyId AND c.p_ChangedOn
> = e.p_Modified_Date)
>     OR  (d.PropertyId = e.PropertyId AND d.p_DeletedOn =
> e.p_Modified_Date))
>
>   FULL OUTER JOIN
>     STG_PropInSewerNetworkLogs f
>     ON ((a.PropertyId = f.PropertyId AND a.p_LastModified =
> f.p_Modified_Date)
>     OR  (b.PropertyId = f.PropertyId AND b.p_Modified_Date =
> f.p_Modified_Date)
>     OR   (c.PropertyId = f.PropertyId AND c.p_ChangedOn =
> f.p_Modified_Date)
>     OR  (d.PropertyId = f.PropertyId AND d.p_DeletedOn =
> f.p_Modified_Date)
>     OR  (e.PropertyId = f.PropertyId AND e.p_Modified_Date =
> f.p_Modified_Date))   FULL OUTER JOIN
>     STG_PropTypeLogs g
>     ON ((a.PropertyId = g .PropertyId AND a.p_LastModified =
> g.p_LastModified)
>     OR  (b.PropertyId = g.PropertyId AND b.p_Modified_Date =
> g.p_LastModified)
>     OR  (c.PropertyId = g.PropertyId AND c.p_ChangedOn = g.p_LastModified)
>     OR  (d.PropertyId = g.PropertyId AND d.p_DeletedOn = g.p_LastModified)
>     OR  (e.PropertyId = g.PropertyId AND e.p_Modified_Date =
> g.p_LastModified)
>     OR  (f.PropertyId = g.PropertyId AND f.p_Modified_Date =
> g.p_LastModified))
>
> -- Luckys

--

Nolan Cafferky
Software Developer
IT Department
RBS Interactive
nolan.cafferky@rbsinteractive.com