Horton

Re: WIP: BRIN multi-range indexes

Zhihong Yu <zyu@yugabyte.com>

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From: Zhihong Yu <zyu@yugabyte.com>
To: Tomas Vondra <tomas.vondra@enterprisedb.com>
Cc: John Naylor <john.naylor@enterprisedb.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2021-02-04T01:35:34Z
Lists: pgsql-hackers 
Hi,
bq. Not sure why would that be an issue

Moving the (start > end) check is up to your discretion.

But the midpoint computation should follow text book :-)

Cheers

On Wed, Feb 3, 2021 at 4:59 PM Tomas Vondra <tomas.vondra@enterprisedb.com>
wrote:

>
>
> On 2/4/21 1:49 AM, Zhihong Yu wrote:
> > Hi,
> > For 0007-Remove-the-special-batch-mode-use-a-larger--20210203.patch :
> >
> > +       /* same as preceding value, so store it */
> > +       if (compare_values(&range->values[start + i - 1],
> > +                          &range->values[start + i],
> > +                          (void *) &cxt) == 0)
> > +           continue;
> > +
> > +       range->values[start + n] = range->values[start + i];
> >
> > It seems the comment doesn't match the code: the value is stored when
> > subsequent value is different from the previous.
> >
>
> Yeah, you're right the comment is wrong - the code is doing exactly the
> opposite. I'll need to go through this more carefully.
>
> > For has_matching_range():
> > +       int     midpoint = (start + end) / 2;
> >
> > I think the standard notion for midpoint is start + (end-start)/2.
> >
> > +       /* this means we ran out of ranges in the last step */
> > +       if (start > end)
> > +           return false;
> >
> > It seems the above should be ahead of computation of midpoint.
> >
>
> Not sure why would that be an issue, as we're not using the value and
> the values are just plain integers (so no overflows ...).
>
>
> regards
>
> --
> Tomas Vondra
> EnterpriseDB: http://www.enterprisedb.com
> The Enterprise PostgreSQL Company
>

Commits

  1. BRIN minmax-multi indexes

  2. BRIN bloom indexes

  3. Support the old signature of BRIN consistent function

  4. Remove unnecessary pg_amproc BRIN minmax entries

  5. Optimize allocations in bringetbitmap

  6. Move IS [NOT] NULL handling from BRIN support functions

  7. Pass all scan keys to BRIN consistent function at once

  8. Properly detoast data in brin_form_tuple