Обсуждение: Trim performance on 9.5

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.

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