Horton

Re: Division in dynahash.c due to HASH_FFACTOR

Thomas Munro <thomas.munro@gmail.com>

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From: Thomas Munro <thomas.munro@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: David Rowley <dgrowleyml@gmail.com>, Jakub Wartak <Jakub.Wartak@tomtom.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2020-09-19T03:55:24Z
Lists: pgsql-hackers 
On Sat, Sep 19, 2020 at 1:30 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> I wrote:
> > ISTM that getting rid of the division obviates the concern that the
> > nentries condition is too expensive,

True, that comment needed to go.

> Also, we could make it slightly cheaper yet, by changing the condition
> to
>
>             hctl->freeList[0].nentries > (long) (hctl->max_bucket)
>
> ie drop the +1.  I'd argue that this is actually a more faithful
> rendition of the previous condition, since what we had before was
> basically
>
>             hctl->freeList[0].nentries >= (long) (hctl->max_bucket + 1)

Agreed, and done.  Thanks!

Commits

  1. Code review for dynahash change.

  2. Remove large fill factor support from dynahash.c.