| From: | "ktm(at)rice(dot)edu" <ktm(at)rice(dot)edu> |
|---|---|
| To: | "David E(dot) Wheeler" <david(at)justatheory(dot)com> |
| Cc: | Michael Glaesemann <grzm(at)seespotcode(dot)net>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL-development Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Document hashtext() and Friends? |
| Date: | 2012-02-21 20:30:59 |
| Message-ID: | 20120221203059.GE21114@aart.rice.edu |
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| Thread: | |
| Lists: | pgsql-hackers |
On Tue, Feb 21, 2012 at 12:14:03PM -0800, David E. Wheeler wrote:
> On Feb 21, 2012, at 12:11 PM, Michael Glaesemann wrote:
>
> > And hashtext *has* changed across versions, which is why Peter Eisentraut published a version-independent hash function library: https://github.com/petere/pgvihash
>
> Yes, Marko wrote one, too:
>
> https://github.com/markokr/pghashlib
>
> But as I’m about to build a system that is going to have many billions of nodes, I could use a variant that returns a bigint. Anyone got a pointer to something like that?
>
> Thanks,
>
> David
>
Hi David,
The existing hash_any() function can return a 64-bit hash, instead of the current
32-bit hash, by returning the b and c values, instead of the current which just
returns the c value, per the comment at the start of the function. It sounded like
Peter had already done this in his pg_stat_statements normalization patch, but I
could not find it.
Regards,
Ken
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