From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Andrus <kobruleht2(at)hot(dot)ee> |
Cc: | pgsql-general <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: How to speed up product code and subcode match |
Date: | 2023-05-23 14:00:25 |
Message-ID: | 908933.1684850425@sss.pgh.pa.us |
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Lists: | pgsql-general |
Andrus <kobruleht2(at)hot(dot)ee> writes:
> Product table as both main products and subproducts with sizes. Size is
> separated by main product code always by / character:
> SHOE1-BLACK
> SHOE1-BLACK/38
> SHOE1-BLACK/41
> SHOE1-BLACK/42
> SHOE1-BLACK/43
> SHOE2/XXL
> SHOE2/L
You could probably have devised a worse data representation if
you really tried, but it would have taken some effort. 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;
Anytime you're trying to join two tables on something that isn't
a plain equality condition (or ANDed conditions), you're in for
a world of hurt.
regards, tom lane
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