From: | Holger Jakobs <holger(at)jakobs(dot)com> |
---|---|
To: | pgsql-admin(at)lists(dot)postgresql(dot)org |
Subject: | Re: Index not always being used |
Date: | 2019-08-29 14:22:36 |
Message-ID: | 43ccec39-3be0-a47c-cd27-fff73d948f20@jakobs.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-admin |
Hi,
A good solution would be to add another B-Tree index. The planner would
choose this one in case of a search using "=" and the trigram index when
using "like", "similar to" or "~" (regexp).
A trigram index is not suitable for a "=" comparison.
Regards,
Holger
Am 29.08.19 um 16:15 schrieb John Scalia:
> I’ve got a table with approximately 5.5 million rows, and one column that is frequently searched is of type varchar(50) and we just put a trigram index on it. Now, if we search “where bld_city = ‘baskingridge’”, explain says a sequential table scan is going to be used, but if I change the query to use “where bold_city like ‘basking%’”, then explain correctly shows that a bitmap index scan will be performed. Why would these two forms use different approaches? I’m a bit confused.
> —
> Jay
>
> Sent from my iPad
>
--
Holger Jakobs, Bergisch Gladbach
instant messaging: xmpp:holger(at)jakobs(dot)com
+49 178 9759012 <tel:+491789759012> oder +49 2202 817157
<tel:+492202817157>
From | Date | Subject | |
---|---|---|---|
Next Message | John Scalia | 2019-08-29 14:29:06 | Re: Index not always being used |
Previous Message | John Scalia | 2019-08-29 14:15:28 | Index not always being used |