Re: Index not always being used

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@jakobs.com
+49 178 9759012 oder +49 2202 817157