Re: todo: Hash index creation

Ühel kenal päeval, E, 2007-07-02 kell 04:27, kirjutas Naz Gassiep:

> I've been warned away from hash indexes before, however I had no idea
> that it's performance was that abysmal that BTREE beat it and I was
> definitely not aware that they were not included in WAL logs. I was told
> it wasn't as good as it could be, but I wasn't told it was pretty much
> an alpha piece of code.
>
> As a result, when creating tables containing large blocks of text I wish
> to index, I've been using HASH as an index method.

If you just wish to have smaller indexes, then you can use functional
btree indexes over text hash, like this:

CREATE INDEX largetextindex on mytable(hashtext(largetext));

and use

SELECT * FROM mytable
where hashtext(largetext) = hastext('searchvalue')
and largetext = 'searchvalue'
;

btw, if the real hash indexes don't get fixes soon, maybe we could
redefine hash index to actually mean usage like this and do the rewrites
in parser?

> Please can we state
> in the manual that HASH index types are in a beta stage of development
> or something similar, or perhaps remove the manual entry altogether
> until HASH is at a point where it is usable in production.
>
> Regards,
> A very surprised n00b.
>
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