Re: Index selection (and partial index) for BYTEA field

From: David Garamond <lists(at)zara(dot)6(dot)isreserved(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Joe Conway <mail(at)joeconway(dot)com>, pgsql-general <pgsql-general(at)postgresql(dot)org>
Subject: Re: Index selection (and partial index) for BYTEA field
Date: 2004-03-20 19:44:26
Message-ID: 405C9F1A.5080409@zara.6.isreserved.com
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-general

Tom Lane wrote:
>>There's no way to force use of either index, but you can probably get
>>your partial index picked if you define the index like:
>>[ example ]
>
> Probably a more practical way is to generate redundant WHERE conditions.
> For instance:
>
> create index i_partition_id_000 on partition(id)
> where id like '\\000%';
> ... etc etc ...
>
> then when you really want to search for \000\001\002% you do:
>
> select * from partition
> where id like '\\000\\001\\002%' AND id like '\\000%';
>
> The second WHERE clause is redundant with the first, but it matches
> the partial index condition so that the index can be used.

That is one cool trick. And it worked!

--
dave

In response to

Browse pgsql-general by date

  From Date Subject
Next Message Mike Sherrill 2004-03-20 23:08:21 Re: Help needed with normalisation
Previous Message Gregory Wood 2004-03-20 19:36:06 Re: transactions in plpgsql