Re: Trim performance on 9.5 - Mailing list pgsql-general

From William Ivanski
Subject Re: Trim performance on 9.5
Date
Msg-id CACaWZ9Qi6343oipj9qos73_tCuza1u5ZWdHJ75TOd8ZoxmUV-g@mail.gmail.com
Whole thread Raw
In response to Re: Trim performance on 9.5  (vinny <vinny@xs4all.nl>)
Responses Re: Trim performance on 9.5
List pgsql-general
I just ran EXPLAIN ANALYZE, please see images attached. Field doesn't have a index.

Em sex, 18 de nov de 2016 às 12:16, vinny <vinny@xs4all.nl> escreveu:
On 2016-11-18 15:06, William Ivanski wrote:
> Hi,
>
> I recently did major improvements on perfomance on our routines by
> simply removing the call for trim functions on specific bottlenecks.
> Please see images attached for a simple example.
>
> I'm using PostgreSQL version 9.5.5-1.pgdg80+1 on Debian 8.6. Someone
> knows if it's a bug on trim function? Thanks in advance.
>
> --
>
> William Ivanski

Did you run EXPLAIN on these queries?

I'm guessing that you have an index on the field, but not on
TRIM(field),
which would mean that the database is forced to seqscan to fetch every
row value, trim it and then compare it.
--

William Ivanski

Attachment

pgsql-general by date:

Previous
From: Vick Khera
Date:
Subject: Re: pgbench and scaling
Next
From: Paul Jungwirth
Date:
Subject: Avoiding double-counting in aggregates with more than one join?