Commit 61461a300c introduced new functions to libpq for cancelling
queries. This commit introduces a helper function that backend-side
libraries and extensions can use to invoke those. This function takes a
timeout and can itself be interrupted while it is waiting for a cancel
request to be sent and processed, instead of being blocked.
This replaces the usage of the old functions in postgres_fdw and dblink.
Finally, it also adds some test coverage for the cancel support in
postgres_fdw.
Author: Jelte Fennema-Nio <postgres@jeltef.nl>
Discussion: https://postgr.es/m/CAGECzQT_VgOWWENUqvUV9xQmbaCyXjtRRAYO8W07oqashk_N+g@mail.gmail.com
Commit 61461a300c introduced new functions to libpq for cancelling
queries. This replaces the usage of the old ones in parts of the
codebase with these newer ones. This specifically leaves out changes to
psql and pgbench, as those would need a much larger refactor to be able
to call them due to the new functions not being signal-safe; and also
postgres_fdw, because the original code there is not clear to me
(Álvaro) and not fully tested.
Author: Jelte Fennema-Nio <postgres@jeltef.nl>
Discussion: https://postgr.es/m/CAGECzQT_VgOWWENUqvUV9xQmbaCyXjtRRAYO8W07oqashk_N+g@mail.gmail.com
This replaces dblink's blocking libpq calls, allowing cancellation and
allowing DROP DATABASE (of a database not involved in the query). Apart
from explicit dblink_cancel_query() calls, dblink still doesn't cancel
the remote side. The replacement for the blocking calls consists of
new, general-purpose query execution wrappers in the libpqsrv facility.
Out-of-tree extensions should adopt these. Use them in postgres_fdw,
replacing a local implementation from which the libpqsrv implementation
derives. This is a bug fix for dblink. Code inspection identified the
bug at least thirteen years ago, but user complaints have not appeared.
Hence, no back-patch for now.
Discussion: https://postgr.es/m/20231122012945.74@rfd.leadboat.com
It's not necessary to fill the key field in most cases, since
hash_search has already done that. Some existing call sites have an
assert or comment that this contract has been fulfilled, but those
are quite old and that practice seems unnecessary here.
While at it, remove a nearby redundant assignment that a smart compiler
will elide anyway.
Zhao Junwang, with some adjustments by me
Reviewed by Nathan Bossart, with additional feedback from Tom Lane
Discussion: http://postgr.es/m/CAEG8a3%2BUPF%3DR2QGPgJMF2mKh8xPd1H2TmfH77zPuVUFdBpiGUA%40mail.gmail.com
Two custom wait events are added here:
- "DblinkConnect", when waiting to establish a connection to a remote
server.
- "DblinkGetConnect", when waiting to establish a connection to a remote
server but it could not be found in the list of already-opened ones.
Author: Masahiro Ikeda
Discussion: https://postgr.es/m/197bce267fa691a0ac62c86c4ab904c4@oss.nttdata.com
The following changes are done:
- Addition of WaitEventBufferPin and WaitEventExtension, that hold a
list of wait events related to each category.
- Addition of two functions that encapsulate the list of wait events for
each category.
- Rename BUFFER_PIN to BUFFERPIN (only this wait event class used an
underscore, requiring a specific rule in the automation script).
These changes make a bit easier the automatic generation of all the code
and documentation related to wait events, as all the wait event
categories are now controlled by consistent structures and functions.
Author: Bertrand Drouvot
Discussion: https://postgr.es/m/c6f35117-4b20-4c78-1df5-d3056010dcf5@gmail.com
Discussion: https://postgr.es/m/77a86b3a-c4a8-5f5d-69b9-d70bbf2e9b98@gmail.com
Run pgindent, pgperltidy, and reformat-dat-files.
This set of diffs is a bit larger than typical. We've updated to
pg_bsd_indent 2.1.2, which properly indents variable declarations that
have multi-line initialization expressions (the continuation lines are
now indented one tab stop). We've also updated to perltidy version
20230309 and changed some of its settings, which reduces its desire to
add whitespace to lines to make assignments etc. line up. Going
forward, that should make for fewer random-seeming changes to existing
code.
Discussion: https://postgr.es/m/20230428092545.qfb3y5wcu4cm75ur@alvherre.pgsql
This reverts commit 3d03b24c3 (Revert Add support for Kerberos
credential delegation) which was committed on the grounds of concern
about portability, but on further review and discussion, it's clear that
we are better off explicitly requiring MIT Kerberos as that appears to
be the only GSSAPI library currently that's under proper maintenance
and ongoing development. The API used for storing credentials was added
to MIT Kerberos over a decade ago while for the other libraries which
appear to be mainly based on Heimdal, which exists explicitly to be a
re-implementation of MIT Kerberos, the API never made it to a released
version (even though it was added to the Heimdal git repo over 5 years
ago..).
This post-feature-freeze change was approved by the RMT.
Discussion: https://postgr.es/m/ZDDO6jaESKaBgej0%40tamriel.snowman.net
This reverts commit 3d4fa227bc.
Per discussion and buildfarm, this depends on APIs that seem to not
be available on at least one platform (NetBSD). Should be certainly
possible to rework to be optional on that platform if necessary but bit
late for that at this point.
Discussion: https://postgr.es/m/3286097.1680922218@sss.pgh.pa.us
Support GSSAPI/Kerberos credentials being delegated to the server by a
client. With this, a user authenticating to PostgreSQL using Kerberos
(GSSAPI) credentials can choose to delegate their credentials to the
PostgreSQL server (which can choose to accept them, or not), allowing
the server to then use those delegated credentials to connect to
another service, such as with postgres_fdw or dblink or theoretically
any other service which is able to be authenticated using Kerberos.
Both postgres_fdw and dblink are changed to allow non-superuser
password-less connections but only when GSSAPI credentials have been
delegated to the server by the client and GSSAPI is used to
authenticate to the remote system.
Authors: Stephen Frost, Peifeng Qiu
Reviewed-By: David Christensen
Discussion: https://postgr.es/m/CO1PR05MB8023CC2CB575E0FAAD7DF4F8A8E29@CO1PR05MB8023.namprd05.prod.outlook.com
Thanks to Robins to find the issue and Nathan for promptly writing a test case
to prevent future problems like this.
Reported-by: Nathan Bossart <nathandbossart@gmail.com>
Reported-by: Robins Tharakan <tharakan@gmail.com>
Author: Nathan Bossart <nathandbossart@gmail.com>
Discussion: https://postgr.es/m/20230130193008.GA2740781@nathanxps13
Until now dblink and postgres_fdw did not process interrupts during connection
establishment. Besides preventing query cancellations etc, this can lead to
undetected deadlocks, as global barriers are not processed.
These aforementioned undetected deadlocks are the reason for the spate of CI
test failures in the FreeBSD 'test_running' step.
Fix the bug by using the helper from libpq-be-fe-helpers.h, introduced in a
prior commit. Besides fixing the bug, this also removes duplicated code
around reserving file descriptors.
As the change is relatively large and there are no field reports of the
problem, don't backpatch for now.
Reviewed-by: Thomas Munro <thomas.munro@gmail.com>
Discussion: https://postgr.es/m/20220925232237.p6uskba2dw6fnwj2@awork3.anarazel.de
Backpatch:
Instead of dozens of mostly-duplicate pg_foo_aclcheck() functions,
write one common function object_aclcheck() that can handle almost all
of them. We already have all the information we need, such as which
system catalog corresponds to which catalog table and which column is
the ACL column.
There are a few pg_foo_aclcheck() that don't work via the generic
function and have special APIs, so those stay as is.
I also changed most pg_foo_aclmask() functions to static functions,
since they are not used outside of aclchk.c.
Reviewed-by: Corey Huinker <corey.huinker@gmail.com>
Reviewed-by: Antonin Houska <ah@cybertec.at>
Discussion: https://www.postgresql.org/message-id/flat/95c30f96-4060-2f48-98b5-a4392d3b6066@enterprisedb.com
Per discussion, the existing routine name able to initialize a SRF
function with materialize mode is unpopular, so rename it. Equally, the
flags of this function are renamed, as of:
- SRF_SINGLE_USE_EXPECTED -> MAT_SRF_USE_EXPECTED_DESC
- SRF_SINGLE_BLESS -> MAT_SRF_BLESS
The previous function and flags introduced in 9e98583 are kept around
for compatibility purposes, so as any extension code already compiled
with v15 continues to work as-is. The declarations introduced here for
compatibility will be removed from HEAD in a follow-up commit.
The new names have been suggested by Andres Freund and Melanie
Plageman.
Discussion: https://postgr.es/m/20221013194820.ciktb2sbbpw7cljm@awork3.anarazel.de
Backpatch-through: 15
The generated resource files aren't exactly the same ones as the old
buildsystems generate. Previously "InternalName" and "OriginalFileName" were
mostly wrong / not set (despite being required), but that was hard to fix in
at least the make build. Additionally, the meson build falls back to a
"auto-generated" description when not set, and doesn't set it in a few cases -
unlikely that anybody looks at these descriptions in detail.
Author: Andres Freund <andres@anarazel.de>
Author: Nazir Bilal Yavuz <byavuz81@gmail.com>
Reviewed-by: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Make sure that function declarations use names that exactly match the
corresponding names from function definitions in contrib code.
Like other recent commits that cleaned up function parameter names, this
commit was written with help from clang-tidy.
Author: Peter Geoghegan <pg@bowt.ie>
Discussion: https://postgr.es/m/CAH2-WznJt9CMM9KJTMjJh_zbL5hD9oX44qdJ4aqZtjFi-zA3Tg@mail.gmail.com
Autoconf is showing its age, fewer and fewer contributors know how to wrangle
it. Recursive make has a lot of hard to resolve dependency issues and slow
incremental rebuilds. Our home-grown MSVC build system is hard to maintain for
developers not using Windows and runs tests serially. While these and other
issues could individually be addressed with incremental improvements, together
they seem best addressed by moving to a more modern build system.
After evaluating different build system choices, we chose to use meson, to a
good degree based on the adoption by other open source projects.
We decided that it's more realistic to commit a relatively early version of
the new build system and mature it in tree.
This commit adds an initial version of a meson based build system. It supports
building postgres on at least AIX, FreeBSD, Linux, macOS, NetBSD, OpenBSD,
Solaris and Windows (however only gcc is supported on aix, solaris). For
Windows/MSVC postgres can now be built with ninja (faster, particularly for
incremental builds) and msbuild (supporting the visual studio GUI, but
building slower).
Several aspects (e.g. Windows rc file generation, PGXS compatibility, LLVM
bitcode generation, documentation adjustments) are done in subsequent commits
requiring further review. Other aspects (e.g. not installing test-only
extensions) are not yet addressed.
When building on Windows with msbuild, builds are slower when using a visual
studio version older than 2019, because those versions do not support
MultiToolTask, required by meson for intra-target parallelism.
The plan is to remove the MSVC specific build system in src/tools/msvc soon
after reaching feature parity. However, we're not planning to remove the
autoconf/make build system in the near future. Likely we're going to keep at
least the parts required for PGXS to keep working around until all supported
versions build with meson.
Some initial help for postgres developers is at
https://wiki.postgresql.org/wiki/Meson
With contributions from Thomas Munro, John Naylor, Stone Tickle and others.
Author: Andres Freund <andres@anarazel.de>
Author: Nazir Bilal Yavuz <byavuz81@gmail.com>
Author: Peter Eisentraut <peter@eisentraut.org>
Reviewed-By: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Discussion: https://postgr.es/m/20211012083721.hvixq4pnh2pixr3j@alap3.anarazel.de
Since these macros just cast whatever you give them to the designated
output type, and many normal uses also cast the output type further, a
number of incorrect uses go undiscovered. The fixes in this patch
have been discovered by changing these macros to inline functions,
which is the subject of a future patch.
Reviewed-by: Aleksander Alekseev <aleksander@timescale.com>
Discussion: https://www.postgresql.org/message-id/flat/8528fb7e-0aa2-6b54-85fb-0c0886dbd6ed%40enterprisedb.com
9e98583 introduced a helper to centralize building their needed state
(tuplestore, tuple descriptors, etc.), checking for any errors. This
commit updates all places of contrib/ that can be switched to use
SetSingleFuncCall() as a drop-in replacement, resulting in the removal
of a lot of boilerplate code in all the modules updated by this commit.
Per analysis, some places remain as they are:
- pg_logdir_ls() in adminpack/ uses historically TYPEFUNC_RECORD as
return type, and I suspect that changing it may cause issues at run-time
with some of its past versions, down to 1.0.
- dblink/ uses a wrapper function doing exactly the work of
SetSingleFuncCall(). Here the switch should be possible, but rather
invasive so it does not seem the extra backpatch maintenance cost.
- tablefunc/, similarly, uses multiple helper functions with portions of
SetSingleFuncCall() spread across the code paths of this module.
Author: Melanie Plageman
Discussion: https://postgr.es/m/CAAKRu_bvDPJoL9mH6eYwvBpPtTGQwbDzfJbCM-OjkSZDu5yTPg@mail.gmail.com
This routine is a no-op since dd04e95 from 2003, with a macro kept
around for compatibility purposes. This has led to the same code
patterns being copy-pasted around for no effect, sometimes in confusing
ways like in pg_logical_slot_get_changes_guts() from logical.c where the
code was actually incorrect.
This issue has been discussed on two different threads recently, so
rather than living with this legacy, remove any uses of this routine in
the C code to simplify things. The compatibility macro is kept to avoid
breaking any out-of-core modules that depend on it.
Reported-by: Tatsuhito Kasahara, Justin Pryzby
Author: Tatsuhito Kasahara
Discussion: https://postgr.es/m/20211217200419.GQ17618@telsasoft.com
Discussion: https://postgr.es/m/CAP0=ZVJeeYfAeRfmzqAF2Lumdiv4S4FewyBnZd4DPTrsSQKJKw@mail.gmail.com
There's no longer any reason to fire up a separate psql run
to create these functions. (Some refactoring in the main
regression tests is also called for, but that will take
more thought.)
Discussion: https://postgr.es/m/1655733.1639871614@sss.pgh.pa.us
"git mv" all the input/*.source and output/*.source files into
the corresponding sql/ and expected/ directories. Then remove
the pg_regress and Makefile infrastructure associated with
dynamic translation.
Discussion: https://postgr.es/m/1655733.1639871614@sss.pgh.pa.us
pg_regress has long had provisions for dynamically substituting path
names into regression test scripts and result files, but use of that
feature has always been a serious pain in the neck, mainly because
updating the result files requires tedious manual editing. Let's
get rid of that in favor of passing down the paths in environment
variables.
In addition to being easier to maintain, this way is capable of
dealing with path names that require escaping at runtime, for example
paths containing single-quote marks. (There are other stumbling
blocks in the way of actually building in a path that looks like
that, but removing this one seems like a good thing to do.) The key
coding rule that makes that possible is to concatenate pieces of a
dynamically-variable string using psql's \set command, and then use
the :'variable' notation to quote and escape the string for the next
level of interpretation.
In hopes of making this change more transparent to "git blame",
I've split it into two steps. This commit adds the necessary
pg_regress.c support and changes all the *.source files in-place
so that they no longer require any dynamic translation. The next
commit will just "git mv" them into the regular sql/ and expected/
directories.
Discussion: https://postgr.es/m/1655733.1639871614@sss.pgh.pa.us
pgfdw_report_error() in postgres_fdw gets a message from PGresult or
PGconn to report an error received from a remote server. Previously
if it could get a message from neither of them, it reported empty
message unexpectedly. The cause of this issue was that pgfdw_report_error()
didn't handle properly the case where no message could be obtained
and its local variable message_primary was set to '\0'.
This commit improves pgfdw_report_error() so that it reports the message
"could not obtain ..." when it gets no message and message_primary
is set to '\0'. This is the same behavior as when message_primary is NULL.
dblink_res_error() in dblink has the same issue, so this commit also
improves it in the same way.
Back-patch to all supported branches.
Author: Fujii Masao
Reviewed-by: Bharath Rupireddy
Discussion: https://postgr.es/m/477c16c8-7ea4-20fc-38d5-ed3a77ed616c@oss.nttdata.com
The foreign data wrapper's validator function provides a HINT message with
list of valid options for the object specified in CREATE or ALTER command,
when the option given in the command is invalid. Previously
postgresql_fdw_validator() and the validator functions for postgres_fdw and
dblink_fdw worked in that way even there were no valid options in the object,
which could lead to the HINT message with empty list (because there were
no valid options). For example, ALTER FOREIGN DATA WRAPPER postgres_fdw
OPTIONS (format 'csv') reported the following ERROR and HINT messages.
This behavior was confusing.
ERROR: invalid option "format"
HINT: Valid options in this context are:
There is no such issue in file_fdw. The validator function for file_fdw
reports the HINT message "There are no valid options in this context."
instead in that case.
This commit improves postgresql_fdw_validator() and the validator functions
for postgres_fdw and dblink_fdw so that they do likewise. For example,
this change causes the above ALTER FOREIGN DATA WRAPPER command to
report the following messages.
ERROR: invalid option "nonexistent"
HINT: There are no valid options in this context.
Author: Kosei Masumura
Reviewed-by: Bharath Rupireddy, Fujii Masao
Discussion: https://postgr.es/m/557d06cebe19081bfcc83ee2affc98d3@oss.nttdata.com
Since at least 2001 we've used putenv() and avoided setenv(), on the
grounds that the latter was unportable and not in POSIX. However,
POSIX added it that same year, and by now the situation has reversed:
setenv() is probably more portable than putenv(), since POSIX now
treats the latter as not being a core function. And setenv() has
cleaner semantics too. So, let's reverse that old policy.
This commit adds a simple src/port/ implementation of setenv() for
any stragglers (we have one in the buildfarm, but I'd not be surprised
if that code is never used in the field). More importantly, extend
win32env.c to also support setenv(). Then, replace usages of putenv()
with setenv(), and get rid of some ad-hoc implementations of setenv()
wannabees.
Also, adjust our src/port/ implementation of unsetenv() to follow the
POSIX spec that it returns an error indicator, rather than returning
void as per the ancient BSD convention. I don't feel a need to make
all the call sites check for errors, but the portability stub ought
to match real-world practice.
Discussion: https://postgr.es/m/2065122.1609212051@sss.pgh.pa.us
Invent a new flag bit HASH_STRINGS to specify C-string hashing, which
was formerly the default; and add assertions insisting that exactly
one of the bits HASH_STRINGS, HASH_BLOBS, and HASH_FUNCTION be set.
This is in hopes of preventing recurrences of the type of oversight
fixed in commit a1b8aa1e4 (i.e., mistakenly omitting HASH_BLOBS).
Also, when HASH_STRINGS is specified, insist that the keysize be
more than 8 bytes. This is a heuristic, but it should catch
accidental use of HASH_STRINGS for integer or pointer keys.
(Nearly all existing use-cases set the keysize to NAMEDATALEN or
more, so there's little reason to think this restriction should
be problematic.)
Tweak hash_create() to insist that the HASH_ELEM flag be set, and
remove the defaults it had for keysize and entrysize. Since those
defaults were undocumented and basically useless, no callers
omitted HASH_ELEM anyway.
Also, remove memset's zeroing the HASHCTL parameter struct from
those callers that had one. This has never been really necessary,
and while it wasn't a bad coding convention it was confusing that
some callers did it and some did not. We might as well save a few
cycles by standardizing on "not".
Also improve the documentation for hash_create().
In passing, improve reinit.c's usage of a hash table by storing
the key as a binary Oid rather than a string; and, since that's
a temporary hash table, allocate it in CurrentMemoryContext for
neatness.
Discussion: https://postgr.es/m/590625.1607878171@sss.pgh.pa.us
Move the system catalog index declarations from catalog/indexing.h to
the respective parent tables' catalog/pg_*.h files. The original
reason for having it split was that the old genbki system produced the
output in the order of the catalog files it read, so all the indexing
stuff needed to come separately. But this is no longer the case, and
keeping it together makes more sense.
Reviewed-by: John Naylor <john.naylor@enterprisedb.com>
Discussion: https://www.postgresql.org/message-id/flat/c7cc82d6-f976-75d6-2e3e-b03d2cab26bb@2ndquadrant.com
The comments in fd.c have long claimed that all file allocations should
go through that module, but in reality that's not always practical.
fd.c doesn't supply APIs for invoking some FD-producing syscalls like
pipe() or epoll_create(); and the APIs it does supply for non-virtual
FDs are mostly insistent on releasing those FDs at transaction end;
and in some cases the actual open() call is in code that can't be made
to use fd.c, such as libpq.
This has led to a situation where, in a modern server, there are likely
to be seven or so long-lived FDs per backend process that are not known
to fd.c. Since NUM_RESERVED_FDS is only 10, that meant we had *very*
few spare FDs if max_files_per_process is >= the system ulimit and
fd.c had opened all the files it thought it safely could. The
contrib/postgres_fdw regression test, in particular, could easily be
made to fall over by running it under a restrictive ulimit.
To improve matters, invent functions Acquire/Reserve/ReleaseExternalFD
that allow outside callers to tell fd.c that they have or want to allocate
a FD that's not directly managed by fd.c. Add calls to track all the
fixed FDs in a standard backend session, so that we are honestly
guaranteeing that NUM_RESERVED_FDS FDs remain unused below the EMFILE
limit in a backend's idle state. The coding rules for these functions say
that there's no need to call them in code that just allocates one FD over
a fairly short interval; we can dip into NUM_RESERVED_FDS for such cases.
That means that there aren't all that many places where we need to worry.
But postgres_fdw and dblink must use this facility to account for
long-lived FDs consumed by libpq connections. There may be other places
where it's worth doing such accounting, too, but this seems like enough
to solve the immediate problem.
Internally to fd.c, "external" FDs are limited to max_safe_fds/3 FDs.
(Callers can choose to ignore this limit, but of course it's unwise
to do so except for fixed file allocations.) I also reduced the limit
on "allocated" files to max_safe_fds/3 FDs (it had been max_safe_fds/2).
Conceivably a smarter rule could be used here --- but in practice,
on reasonable systems, max_safe_fds should be large enough that this
isn't much of an issue, so KISS for now. To avoid possible regression
in the number of external or allocated files that can be opened,
increase FD_MINFREE and the lower limit on max_files_per_process a
little bit; we now insist that the effective "ulimit -n" be at least 64.
This seems like pretty clearly a bug fix, but in view of the lack of
field complaints, I'll refrain from risking a back-patch.
Discussion: https://postgr.es/m/E1izCmM-0005pV-Co@gemulon.postgresql.org
Andres Freund pointed out that allowing non-superusers to run
"CREATE EXTENSION ... FROM unpackaged" has security risks, since
the unpackaged-to-1.0 scripts don't try to verify that the existing
objects they're modifying are what they expect. Just attaching such
objects to an extension doesn't seem too dangerous, but some of them
do more than that.
We could have resolved this, perhaps, by still requiring superuser
privilege to use the FROM option. However, it's fair to ask just what
we're accomplishing by continuing to lug the unpackaged-to-1.0 scripts
forward. None of them have received any real testing since 9.1 days,
so they may not even work anymore (even assuming that one could still
load the previous "loose" object definitions into a v13 database).
And an installation that's trying to go from pre-9.1 to v13 or later
in one jump is going to have worse compatibility problems than whether
there's a trivial way to convert their contrib modules into extension
style.
Hence, let's just drop both those scripts and the core-code support
for "CREATE EXTENSION ... FROM".
Discussion: https://postgr.es/m/20200213233015.r6rnubcvl4egdh5r@alap3.anarazel.de
We used to strategically place newlines after some function call left
parentheses to make pgindent move the argument list a few chars to the
left, so that the whole line would fit under 80 chars. However,
pgindent no longer does that, so the newlines just made the code
vertically longer for no reason. Remove those newlines, and reflow some
of those lines for some extra naturality.
Reviewed-by: Michael Paquier, Tom Lane
Discussion: https://postgr.es/m/20200129200401.GA6303@alvherre.pgsql
Using \ is unnecessary and ugly, so remove that. While at it, stitch
the literals back into a single line: we've long discouraged splitting
error message literals even when they go past the 80 chars line limit,
to improve greppability.
Leave contrib/tablefunc alone.
Discussion: https://postgr.es/m/20191223195156.GA12271@alvherre.pgsql
This patch providies for support for password protected SSL client
keys in libpq, and for DER format keys, both encrypted and unencrypted.
There is a new connection parameter sslpassword, which is supplied to
the OpenSSL libraries via a callback function. The callback function can
also be set by an application by calling PQgetSSLKeyPassHook(). There is
also a function to retreive the connection setting, PQsslpassword().
Craig Ringer and Andrew Dunstan
Reviewed by: Greg Nancarrow
Discussion: https://postgr.es/m/f7ee88ed-95c4-95c1-d4bf-7b415363ab62@2ndQuadrant.com
When maintaining or merging patches, one of the most common sources
for conflicts are the list of objects in makefiles. Especially when
the split across lines has been changed on both sides, which is
somewhat common due to attempting to stay below 80 columns, those
conflicts are unnecessarily laborious to resolve.
By splitting, and alphabetically sorting, OBJS style lines into one
object per line, conflicts should be less frequent, and easier to
resolve when they still occur.
Author: Andres Freund
Discussion: https://postgr.es/m/20191029200901.vww4idgcxv74cwes@alap3.anarazel.de
Alvaro Herrera