Re: Query planner question

At 23:56 12.06.2003, Stephan Szabo said:
--------------------[snip]--------------------
>I think that it doesn't entirely know that owid=1, sort by dcid, dsid,
>drid can be handled by that index.  I think it's possible that if you
>added owid to the select list it might use id_dowid instead. I think this
>is similar to the issues with order by, conditions and index choice, which
>you may find useful information in the archives about)

Nope, still uses the wrong index, but as I said to Dimitry that's my least
problem ;-)

>> 2) Why is NO index used for the second query, the only difference being in
>> the constraint value (owid is set vs. owid is null)?
>
>IS NULL is not considered an indexable condition currently (there are past
>discussions and hackarounds in the archives)

Hmm - I'm not into hackarounds on a production server, really. I'll rather
modify the approach the application takes.

>> 3) Why does it use id_dictid for the second query when forced to, and not
>> id_owid or id_dowid?
>
>As for #2, it doesn't think it can use an index with owid in the front.

Makes perfectly sense since nulls can't be indexed *sigh*

Anyone know why this decision has been taken?

Thanks for your insight, guys :)


--
   >O     Ernest E. Vogelsinger
   (\)    ICQ #13394035
    ^     http://www.vogelsinger.at/