| From: | "Olivier Hubaut" <olivier(at)scmbb(dot)ulb(dot)ac(dot)be> |
|---|---|
| To: | pgsql-sql(at)postgresql(dot)org |
| Subject: | Re: INDEX and LIKE |
| Date: | 2004-11-29 13:45:42 |
| Message-ID: | opsh8a6gzu94ope3@olivier.amaze.ulb.ac.be |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-sql |
On Mon, 29 Nov 2004 12:19:12 +0000, T E Schmitz
<mailreg(at)numerixtechnology(dot)de> wrote:
> Hello,
>
> I need to be able to perform wildcard searches on a VARCHAR(100) column
> of the form
>
> SELECT * FROM item WHERE serial_no LIKE '%12345678%'
>
> Would an index on serial_no do anything at all for this search?
>
No, It wouldn't. If you use "%" for the beginning of you search pattern, a
seqential search is performed, ignoring the index wich use the beginning
of the string in order to create it's B-tree.
--
Downloading signature ... 99%
*CRC FAILED*
signature aborted
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Dave Steinberg | 2004-11-29 16:19:30 | Re: PG7.4.5: query not using index on date column |
| Previous Message | T E Schmitz | 2004-11-29 12:19:12 | INDEX and LIKE |