Re: Special index for "like"-based query

On 12/30/2016 12:33 AM, David G. Johnston wrote:
> On Thu, Dec 29, 2016 at 4:21 PM, Job <Job(at)colliniconsulting(dot)it
> <mailto:Job(at)colliniconsulting(dot)it>>wrote:
>
> Hello,
>
> in Postgresql 9.6 we have a query running on a very large table
> based, in some cases, on a like statement:
>
> ... WHERE FIELD='CODE' OR FIELD LIKE 'CODE_%'
>
> Which type of index can i create to speed to the search when the
> "like" case happens?
>
>
> ​GIST​
>
> https://www.postgresql.org/docs/9.6/static/pgtrgm.html
>
> ​https://www.postgresql.org/docs/9.6/static/btree-gist.html
> ​

For prefix queries, it's also possible to use simple btree index with
varchar_pattern_ops.

https://www.postgresql.org/docs/9.6/static/indexes-opclass.html

regards

--
Tomas Vondra http://www.2ndQuadrant.com
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