maria-developers team mailing list archive

[Jocelyn Fournier <joce@xxxxxxxxxxxxx>]

Hi,

Will this fix also solve the bug http://bugs.mysql.com/bug.php?id=36817  
(and reopened in maria as https://bugs.launchpad.net/maria/+bug/639949 ) ?

Thanks and regards,
  Jocelyn Fournier


Le 19/05/2011 16:46, Michael Widenius a écrit :
> Hi!
>
> > > > > > "Zardosht" == Zardosht Kasheff<zardosht@xxxxxxxxx>  writes:
> Zardosht>  The issue that I see with this proposal is that if quick_records is
> Zardosht>  much much greater than best_records, then we may not want to set
> Zardosht>  best_key to nr even though this nr is a covering index.
>
> Agree, but this is what is happening with covering indexes anyway if
> they where found before a normal index.
>
> This comes from the code a bit higher up:
>
>              if ((is_best_covering&&  !is_covering) ||
>                  (is_covering&&  ref_key_quick_rows<  select_limit))
>                continue;
>
> The first part of this test means that as soon as we have found a
> covering index, all other index are disregarded.
> My change fixes things so that all clustered indexes are treated
> equal, in spite of their position among the keys.
>
> The right way to fix this is to calculate the cost of the index and
> remove the testing of number of key parts and covering keys.
>
> I will look at this as soon as all my other 5.3 tasks are done.
> (ETA: 1-2 weeks)
>
> Regards,
> Monty
>
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