Re: Index on substring

[Szymon Guz <mabewlun@xxxxxxxxx>]

2011/6/5 HÃvard Wahl KongsgÃrd <haavard.kongsgaard@xxxxxxxxx>

Hi, my database performance badly on substring comparison between two very large tables.Â

In postgresql 8.4 is it possible to create a index on aÂsubstring, or must I create an new field for the substring match ( and then create a new index for that field)?

--
HÃvard Wahl KongsgÃrd

http://havard.security-review.net/

Hi,

I've checked that for 9.0, however for 8.4 should work as well:

CREATE INDEXÂÂi_test_sbstr ON test( substring(t, 5, 3) );

It is important that the substring() parameters in the index definition are the same as you use in your query.

regards

Szymon