Re: Patch queue triage

Tom Lane wrote:
> * [pgsql-patches] Ctid chain following enhancement
> /Pavan Deolasee/
>
> I'm not very excited about this --- it seems to me to complicate the code
> in some places that are not in fact performance-critical. While it
> doesn't seem likely to break things, I'm not in favor of reducing code
> readability unless a measurable performance improvement can be shown.
> Can we have some tests showing this is worthwhile?

IIRC this patch was originally part of an old HOT patch, and it was
submitted as a separate patch because it has some benefit on its own but
more importantly getting it applied first would make the HOT patch
slightly smaller. I'm not sure if the latest HOT patch requires or
includes this change anymore. If not we should drop this. If it does,
then let's deal with this before attacking the hard core of HOT.

> * [HACKERS] Grouped Index Tuples /Heikki Linnakangas/
> * [HACKERS] Grouped Index Tuples / Clustered Indexes
> /Heikki Linnakangas/
>
> Needs review. I'm not sure how many people besides Heikki have really
> looked at this (I know I haven't).

The patch is ugly as it is. We need API changes to make it less ugly, I
had hoped to discuss and reach consensus on them well before feature
freeze, that's what the "indexam API proposal" and "Stream bitmaps"
threads in the patch queue are all about. But those discussions and
patches stalled, so the clustered index patch is still in the same ugly
state.

I'm afraid we're getting "past due" on clustered indexes. The patch
isn't ready for committing as it is, and we still don't have agreement
on the API changes or even on the design in general. :(

> * [HACKERS] Stream bitmaps /Heikki Linnakangas/
>
> I think this is on hold unless a finished bitmap-index patch shows up;
> however there was some discussion of using this in support of clustered
> indexes, so maybe it's live anyway? Heikki?

This particular thread is closely related to bitmap indexes. But see
next item:

> * Re: [HACKERS] [PATCHES] Bitmapscan changes
> /Heikki Linnakangas/
>
> I had objected to this on the grounds that it seemed to be covering
> only a narrow territory between HOT and bitmap indexes, but given the
> probability that one or even both of those won't make it, we need to
> give this one a second look. So: live, needs review.

Are you talking about the patch I submitted at the beginning of that
thread? Because the mail in the patch queue is actually about whether or
not we want clustered indexes.

I think the original "bitmapscan changes" patch I submitted is live and
needs review, even if clustered indexes and bitmap indexes are rejected.
It should give some performance benefit when you do bitmap ANDs with
partially lossy bitmaps, and from setting bits directly in the bitmap in
the indexam in one call, instead of calling amgetmulti many times.
Though I never measured that.

> * [HACKERS] Indexam interface proposal /Heikki Linnakangas/
>
> AFAICS this discussion died out with no actual patch submitted.

This is part of clustered indexes.. This was my proposal of what the
indexam API changes would be like. This patch is either live or dead
together with clustered indexes.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com