Re: documentation for hashtext?

>
> hashtext
>

I believe it's considered an internal function, and not one to rely
> on. If you search the archives, you will find reports around a version
> upgrade when it changed the output for a certain input and thus broke
>

yes. I did find that discussion, and a blog post by Peter E. about this
breakage.

BUT...
http://kaiv.wordpress.com/2007/07/23/decreasing-the-index-size-on-wide-columns/

then there is skytools ... using hashtext for various things, and the
report:

http://postgresql.1045698.n5.nabble.com/Which-is-faster-md5-or-hashtext-td3251399.html

describing it is fact roughly 40% faster then md5 AND is an integer, so

select sum(hastext(t.*::text)) as signature from datable t

as a fast way of comparing 2 replicated tables is really something to
consider....

> conclusion was that it's not documented because it's internal and
> you're not supposed to use/rely on it.
>
> My impression is that people are allready using it, relying their sharding
on it, even building indexes on it.

So... I suggest we start documenting it. Even if there was a recommendation
not to use it, people will get hurt anyway if their application rely on it
and it breaks.

Could I persuade?

Harald

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