Re: hash_create API changes (was Re: speedup tidbitmap patch: hash BlockNumber)

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Teodor Sigaev <teodor(at)sigaev(dot)ru>
Cc: David Rowley <dgrowleyml(at)gmail(dot)com>, Pgsql Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: hash_create API changes (was Re: speedup tidbitmap patch: hash BlockNumber)
Date: 2014-12-18 02:20:34
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I wrote:
> However, there's another way we could attack this,
> which is to invent a new hash option flag bit that says "pick a suitable
> hash function for me, assuming that all bits of the specified key size are
> significant". So instead of

> ctl.keysize = sizeof(...);
> ctl.entrysize = sizeof(...);
> ctl.hash = tag_hash;
> tab = hash_create("...", ..., &ctl,

> you'd write

> ctl.keysize = sizeof(...);
> ctl.entrysize = sizeof(...);
> tab = hash_create("...", ..., &ctl,

> which would save some code space and is arguably cleaner than the
> current approach of specifying some support functions and not others.

Here's a proposed patch along this line. I left in oid_hash (in the
form of a macro) so that this does not cause any API break for existing
third-party modules. However, no callers in our own code directly
refer to tag_hash or oid_hash anymore.

regards, tom lane

Attachment Content-Type Size
make-dynahash-select-normal-hash-functions-1.patch text/x-diff 60.4 KB

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