Re: How to speed up product code and subcode match

Andrus <kobruleht2@hot.ee>

From: Andrus <kobruleht2@hot.ee>
To: Tom Lane <tgl@sss.pgh.pa.us>, "Bzm@g" <bzm@2bz.de>
Cc: pgsql-general <pgsql-general@postgresql.org>
Date: 2023-05-23T14:26:12Z
Lists: pgsql-general
Hi!

> Separate
> the product code and size into two columns --- if there's somebody
> who really wants to see them in the above format, give them a
> view or generated column.  Then instead of the impossible-to-optimize
> queries you showed, you could do something like
>
> select toode.toode , n2, n3, n4
> from toode, vordlusajuhinnak
> where toode.toode = vordlusajuhinnak.toode;
>
Can function index

create index on toode ( *split_part( toode, '/',1) *)

and query

select toode.toode , n2, n3, n4

from toode, vordlusajuhinnak

where *split_part( toode.toode, '/',1) *= vordlusajuhinnak.toode;


used and keeping existing table structure? Functional index should 
produce same speed improvement as using separate column?

Andrus.