Re: Indexes on array columns

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От karly@kipshouse.org
Тема Re: Indexes on array columns
Дата
Msg-id 20060315223013.A4976@kipshouse.org
обсуждение исходный текст
Ответ на Indexes on array columns  (Brendan Duddridge <brendan@clickspace.com>)
Ответы Re: Indexes on array columns
Список pgsql-general
On Wed, Mar 15, 2006 at 09:36:04AM -0700, Brendan Duddridge wrote:
> Hi,
>
> Is it possible to put an index on an array column?

Apparently yes (I just did it as a test).  However, consider the
following from the manual.

   Tip:  Arrays are not sets; searching for specific array elements
   may be a sign of database misdesign. Consider using a separate
   table with a row for each item that would be an array element. This
   will be easier to search, and is likely to scale up better to large
   numbers of elements.[1]

Arrays are attractive, but it seems they most often aren't the best
solution. FOr instance, I beleive I read somewhere that the index
will be on the whole array, and the individual elements are not
indexed, so

   WHERE ary = {foo,bar}

might benefit from your index, but

   WHERE 'foo' = ANY(ary)

probably wouldn't.  At least that's the impression I got from
reading the archives of this list.  I haven't done any testing of
it.


-karl



1. http://www.postgresql.org/docs/8.0/interactive/arrays.html#AEN5491

>
> Thanks,
>
> ____________________________________________________________________
> Brendan Duddridge | CTO | 403-277-5591 x24 |  brendan@clickspace.com
>
> ClickSpace Interactive Inc.
> Suite L100, 239 - 10th Ave. SE
> Calgary, AB  T2G 0V9
>
> http://www.clickspace.com
>



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