Re: postgres feature matrix - Mailing list pgsql-www

On 2/10/20 12:03 PM, Justin Pryzby wrote:
> Hi,
>
> I was curious about how this is maintained ?
> https://www.postgresql.org/about/featurematrix/
>
> I imagine someone extracts most significant stuff from the release notes?

*waves*

Here has been the process over the past few years:

1. First, I do some "cleaning" / consolidation based on the current
state of the feature matrix. For example, before the PostgreSQL 11
release, I did some heavy reorganizing / recategorization based on the
current state of PostgreSQL to try to make it more readable and easier
to navigate. One of the bigger changes introduced was, by default,
listing out all features, instead of just the differences between the
latest 5-6 supported releases.

2. I typically wait until late in the beta period before doing a full
sweep of the release notes, to know exactly what is making it in or not
for the final release. I do try to add some of the features on-or-around
the initial beta to drive awareness, but the usability of the features
is typically better understood as the beta period progresses (and even
moreso after release).

The impact of certain features becomes apparent after the release, in
which case they can subsequently be added. For instance, the B-tree
index performance improvements in PG12 are certainly impactful, but
tough to put into the feature matrix.

You could point out that it appears such things may exist in the list,
which is a product of having the feature matrix around for awhile (and
hence why I try to continually prune/reorganize :)

This leads to:

> I'm not able to find this one:
> https://www.postgresql.org/docs/12/release-12.html
> |Allow partition elimination during query execution (David Rowley, Beena Emerson)
> |Previously, partition elimination only happened at planning time, meaning many joins and prepared queries could not
usepartition elimination. 
>
> https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=499be013de65242235ebdde06adb08db887f0ea5

Yeah, this is an awesome contribution, and was one of the major features
highlighted in the release notes and press release.

When I first looked at it, this one was a bit tricky to figure out in
the feature matrix, i.e. what does it mean for other performance
enhancements that are added in? As mentioned, we've tried to stick to
specific features we can point at on the feature matrix vs. general
improvements.

However, looking at this again, I think the key "feature" to point out
is that partition elimination can occur during query execution. But,
what does that mean to most users? That's a tricky question :)

That said, I'll take a whirl at giving partition pruning it's due in the
feature matrix and hope to have something up shortly.

> Also, it'd be nice if the author's names were included at these pages:
> https://www.postgresql.org/about/featurematrix/detail/249/

This is not a bad idea, however we would need to ensure this is applied
consistently. The original (and still used) feature matrix code allows
you to pass in a URL directly to the documentation directly, which, if
present, brings the user directly to the documentation. The authors of
features in that regard would not be recognized, unless we remove that
functionality.

Additionally, while I wholly support the effort of patch authors (for
fairly obvious reasons :) the feature matrix may not be the best place
for that. The typical user coming to the feature matrix is trying to get
a better understanding of what PostgreSQL offers; the returning user is
trying to understand the differences between the major versions when
making the calculus to upgrade.

My personal preference would be your below suggestion:

>
> It'd be nice too if there were a page indexed by author listing major
> contributions.  Maybe for major contributors that would be visible here:
> https://www.postgresql.org/community/contributors/

IIRC Alvaro Herrera made a change in the documentation that would allow
us to do this automatically, and we need to incorporate this into pgweb.

Thanks,

Jonathan