Re: 9.5 release notes

On Tue, Jun 30, 2015 at 09:00:44PM +0200, Andres Freund wrote:
> I've gone through the release notes and added comments referencing
> commits as discussed earlier. Additionally I've improved and added a
> bunch of items.
>
> Further stuff that came up while looking:
> * 2014-09-25 [b0d81ad] Heikki..: Add -D option to specify data directory to pg_c..
> new options, should possibly be documented?

As I remember it was added just for consistency with other tools and is
not expected to be used because the data directory is required, so
documenting it seems like it would encourage nonsensical use.

> * 2014-10-02 [3acc10c9] Robert..: Increase the number of buffer mapping partition..
> should we mention this? This has been patched by a number of
> downstream vendors and users, so it's probably worth calling out?

Uh, I am not sure why general users would care.

> * 2014-11-18 [606c012] Simon ..: Reduce btree scan overhead for < and > strategies
> Worthy of a note in the performance section.

I commented on this already.

> * 2014-11-22 [eca2b9b] Andrew..: Rework echo_hidden for \sf and \ef from commit ..
> Seems far too minor in comparison to other stuff left out.

This is a user-visible change.

> * 2014-11-07 [7516f52] Alvaro..: BRIN: Block Range Indexes
> Looks to me like that should just be Alvaro.

OK, other names removed.

> * 2014-11-22 [b62f94c] Tom Lane: Allow simplification of EXISTS() subqueries con..
> Planner change, I think it's good to mention those.

I have talked to Tom about this in the past and unless the item has a
user-visible componient, in general he doesn't think they should be
mentioned. I added a bunch of planner items in the major release notes
years ago and he thought they should be removed, and they were.

>
> * 2014-11-28 [e384ed6] Tom Lane: Improve typcache: cache negative lookup results..
> Should perhaps, together with other cache enhancing entries, be mentioned?

Uh, I am not seeing it.

> * 2014-12-08 [519b075] Simon ..: Use GetSystemTimeAsFileTime directly in win32
> 2014-12-08 [8001fe6] Simon ..: Windows: use GetSystemTimePreciseAsFileTime if ..
> Timer resolution isn't a unimportant thing for people using explain?

This all seemed very internals-only, e.g.:

On most Windows systems this change will actually have no significant effect on
timestamp resolution as the system timer tick is typically between 1ms and 15ms
depending on what timer resolution currently running applications have
requested. You can check this with clockres.exe from sysinternals. Despite the
platform limiation this change still permits capture of finer timestamps where
the system is capable of producing them and it gets rid of an unnecessary
syscall.

Was I wrong?

> * 2014-12-12 [7e354ab] Andrew..: Add several generator functions for jsonb that ..
> 2015-05-12 [c694701] Andrew..: Additional functions and operators for jsonb
> 2015-05-31 [37def42] Andrew..: Rename jsonb_replace to jsonb_set and allow it ..
> 2014-12-12 [237a882] Andrew..: Add json_strip_nulls and jsonb_strip_nulls fun..
> should probably be merged? Similar set of authors and too many similar release note
> entries.

They all do different types of things, hance the different entries.

> * 2014-12-23 [d7ee82e] Alvaro..: Add SQL-callable pg_get_object_address
> * 2014-12-30 [a676201] Alvaro..: Add pg_identify_object_as_address
> should be merged.

OK, merged.

> * 2015-01-13 [4bad60e] Andres..: Allow latches to wait for socket writability wi..
> 2015-01-14 [59f71a0] Andres..: Add a default local latch for use in signal han..
> 2015-01-17 [ff44fba] Andres..: Replace walsender's latch with the general shar..
> 2015-02-03 [387da18] Andres..: Use a nonblocking socket for FE/BE communicatio..
> 2015-02-03 [4f85fde] Andres..: Introduce and use infrastructure for interrupt ..
> 2015-02-03 [4fe384b] Andres..: Process 'die' interrupts while reading/writing ..
> 2015-02-03 [6647248] Andres..: Don't allow immediate interrupts during authent..
> 2015-02-03 [6753333] Andres..: Move deadlock and other interrupt handling in p..
> 2015-02-13 [80788a4] Heikki..: Simplify waiting logic in reading from /writin..

Again, I am willing to add an combined entry for these, but I can't
figure out accurate text for it.

> * 2015-01-17 [9402869] Heikki..: Advance backend's advertised xmin more aggressi..
> This is a pretty big efficiency boon for systems with longer
> nontrivial transactions.

What is the user-visible behavior here? More aggressive cleanup?

> * 2015-01-29 [ed12700] Andres..: Align buffer descriptors to cache line boundari..
> Maybe worthwhile to mention?

Uh, I think you and I worked on that. Odd I didn't list it, but I don't
think it fit in with any user-visible behavior, and was rare in that it
only happened on larger systems.

> * 2015-02-16 [9e3ad1a] Tom Lane: Use fast path in plpgsql's RETURN/RETURN NEXT i..
> 2015-02-28 [e524cbd] Tom Lane: Track typmods in plpgsql expression evaluation ..
> 2015-03-04 [1345cc6] Tom Lane: Use standard casting mechanism to convert types..
> 2015-03-11 [21dcda2] Tom Lane: Allocate ParamListInfo once per plpgsql functio..
>
> Maybe reformulate to generalize the array performance into plpgsql and
> mention arrays and RETURN? And combine with the casting change entry,
> because that's also about performance?

Sure. Can you suggest some text?

> * 2015-02-20 [09d8d11] Tom Lane: Use FLEXIBLE_ARRAY_MEMBER in a bunch more places.
> 2015-02-20 [5740be6] Tom Lane: Some more FLEXIBLE_ARRAY_MEMBER hacking.
> 2015-02-20 [e38b1eb] Tom Lane: Use FLEXIBLE_ARRAY_MEMBER in struct varlena.
> 2015-02-20 [c110eff] Tom Lane: Use FLEXIBLE_ARRAY_MEMBER in struct RecordIOData.
> 2015-02-20 [33a3b03] Tom Lane: Use FLEXIBLE_ARRAY_MEMBER in some more places.
> 2015-02-20 [33b2a2c] Tom Lane: Fix statically allocated struct with FLEXIBLE_A..
> 2015-02-21 [f2874fe] Tom Lane: Some more FLEXIBLE_ARRAY_MEMBER fixes.
> 2015-02-21 [e1a11d9] Tom Lane: Use FLEXIBLE_ARRAY_MEMBER for HeapTupleHeaderDa..
> 2015-02-21 [2e21121] Tom Lane: Use FLEXIBLE_ARRAY_MEMBER in a number of other ..
> Maybe add a note in the source code section? Not sure if relevant enough.

I am thinking no. Anyone else?

> * 2015-02-21 [b419865] Jeff D..: In array_agg(), don't create a new context for ..
> Peformance improvement?

Again, I didn't think so. We don't document all performance
improvements, only big ones that would change user behavior or choices,
in general.

> * 2015-02-27 [f65e827] Tom Lane: Invent a memory context reset/delete callback m..
> Interesting for devs, maybe add?

No idea.

> * 2015-03-11 [b557226] Tom Lane: Improve planner's cost estimation in the presen..
> 2015-03-03 [b989619] Tom Lane: Fix cost estimation for indexscans on expensive..
> 2015-03-11 [f4abd02] Tom Lane: Support flattening of empty-FROM subqueries and..
> 2015-05-04 [2503982] Tom Lane: Improve procost estimates for some text search ..
> Mention? Notes about planner changes rather helpful when trying to pin
> down performance regression.s

Again, see above on when planner changes are mentioned.

> * 2015-03-18 [f9dead5] Alvaro..: Install shared libraries to bin/ in Windows und..
> Shouldn't this be mentioned rather than unimportant stuff like

Uh, we do mention this:

Install shared libraries to <filename>bin</> in <systemitem
class="osname">MS Windows</> (Peter Eisentraut, Michael Paquier)

> * 2015-03-23 [e5f455f] Tom Lane: Apply table and domain CHECK constraints in nam..
> I think this should be dropped, it has essentially no consequence to users.

Actually, the ordering of CHECK constraint checks was previously
indeterminate, and users might have been depending on the order of
failure, while now it is consistent --- this is a user-visible change.

> * 2015-03-24 [1d8198b] Bruce ..: Add support for ALTER TABLE IF EXISTS ... RENAM..
> Should imo be wrapped together with the other IF EXISTS changes

Uh, there is only one IF EXIST entry; there is an IF NOT EXISTS, but
that is different.

> * 2014-12-09 [ae4e688] Simon ..: Silence REINDEX
> Doesn't seem to warrant a separate release note entry.

The original behavior now requires use of the new VERBOSE option.

> * 2015-05-19 [0b28ea7] Tom Lane: Avoid collation dependence in indexes of syste..
> Doesn't seem to warrant a separate release note entry. We've left of
> many more significant things.

It is a bug fix.

> * 2015-04-14 [9fa8b0e] Peter ..: Move pg_upgrade from contrib/ to src/bin/
> 2015-04-13 [81134af] Peter ..: Move pgbench from contrib/ to src/bin/
> Should imo merged with all the other moved utilities.

These items already had their own release note sections.

> * 2014-07-14 [91f03ba] Noah M..: MSVC: Recognize PGFILEDESC in contrib and conv..
> 2015-04-16 [22d0053] Alvaro..: MSVC: install src/test/modules together with c..
> Don't seem to warrant a release note entry.

User-visible changes.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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