Groups > comp.databases.oracle.misc > #793

Re: Query optimization

From	Robert Klemme <shortcutter@googlemail.com>
Newsgroups	comp.databases.oracle.misc
Subject	Re: Query optimization
Date	2014-01-11 11:55 +0100
Message-ID	<bjcm9rFsdo2U1@mid.individual.net> (permalink)
References	<d9svc9htpv6k2mniepdfhp08jgmk7o25k6@4ax.com> <yHTzu.193917$5Z5.148829@fx05.iad> <8n70d9l87hqm7p5n55o0pa4c1h9qlj0gbq@4ax.com>

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On 10.01.2014 17:33, Mark wrote:
> On Fri, 10 Jan 2014 14:44:46 GMT, "Ken" <ktsahl@yoohoo.com> wrote:

> The query is as simple as this:
>
>     SELECT column FROM table WHERE x = 'a' AND y = 'b' AND z = 1;
>
> There is an index on x, y and z.

Do you mean "there is a covering index on (x, y, z)" or do you mean 
"there is an index on x, an index on y and an index on z"?  If the 
latter, try the covering index with the most selective column first.

> Anyway my client has solved the problem by setting the statistics to
> NULL.

Other queries aren't hurt?

Cheers

	robert

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Thread

Query optimization Mark <i@dontgetlotsofspamanymore.invalid> - 2014-01-10 13:14 +0000
  Re: Query optimization "Ken" <ktsahl@yoohoo.com> - 2014-01-10 14:44 +0000
    Re: Query optimization Mark <i@dontgetlotsofspamanymore.invalid> - 2014-01-10 16:33 +0000
      Re: Query optimization Robert Klemme <shortcutter@googlemail.com> - 2014-01-11 11:55 +0100
        Re: Query optimization Mark <i@dontgetlotsofspamanymore.invalid> - 2014-01-13 10:05 +0000
      Re: Query optimization "Ken" <ktsahl@yoohoo.com> - 2014-01-13 03:08 +0000
        Re: Query optimization Mark <i@dontgetlotsofspamanymore.invalid> - 2014-01-13 10:07 +0000
          Re: Query optimization "Kirby Grant" <kgrant@whatzit.org> - 2014-01-13 13:24 +0000
            Re: Query optimization Mark <i@dontgetlotsofspamanymore.invalid> - 2014-01-13 15:32 +0000
  Re: Query optimization ddf <oratune@msn.com> - 2014-01-10 08:24 -0800
    Re: Query optimization Mark <i@dontgetlotsofspamanymore.invalid> - 2014-01-10 17:03 +0000
      Re: Query optimization ddf <oratune@msn.com> - 2014-01-10 15:39 -0800
      Re: Query optimization joel garry <joel-garry@home.com> - 2014-01-10 15:46 -0800
        Re: Query optimization Mark <i@dontgetlotsofspamanymore.invalid> - 2014-01-13 10:51 +0000

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