The hex_encode() and hex_decode() functions serve as the workhorses
for hexadecimal data for bytea's text format conversion functions,
and some workloads are sensitive to their performance. This commit
adds new implementations that use routines from port/simd.h, which
testing indicates are much faster for larger inputs. For small or
invalid inputs, we fall back on the existing scalar versions.
Since we are using port/simd.h, these optimizations apply to both
x86-64 and AArch64.
Author: Nathan Bossart <nathandbossart@gmail.com>
Co-authored-by: Chiranmoy Bhattacharya <chiranmoy.bhattacharya@fujitsu.com>
Co-authored-by: Susmitha Devanga <devanga.susmitha@fujitsu.com>
Reviewed-by: John Naylor <johncnaylorls@gmail.com>
Discussion: https://postgr.es/m/aLhVWTRy0QPbW2tl%40nathan
The WAL records XLOG_GIN_INSERT and XLOG_GIN_VACUUM_DATA_LEAF_PAGE
included some information about the blocks added to the record.
This information is already provided by XLogRecGetBlockRefInfo() with
much more details about the blocks included in each record, like the
compression information, for example. This commit removes the block
information that existed in the record descriptions specific to GIN.
Author: Kirill Reshke <reshkekirill@gmail.com>
Reviewed-by: Andrey Borodin <x4mmm@yandex-team.ru>
Discussion: https://postgr.es/m/CALdSSPgk=9WRoXhZy5fdk+T1hiau7qbL_vn94w_L1N=gtEdbsg@mail.gmail.com
It is possible to call pg_stat_reset_single_table_counters() on a
relation (index or table) but the reset time was missing from the system
views showing their statistics.
This commit adds the reset time as an attribute of pg_stat_all_tables,
pg_stat_all_indexes, and other relations related to them.
Bump catalog version.
Bump PGSTAT_FILE_FORMAT_ID, as a result of the new field added to
PgStat_StatTabEntry.
Author: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Reviewed-by: Sami Imseih <samimseih@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/aN8l182jKxEq1h9f@paquier.xyz
stats.sql is already doing some tests coverage on index statistics, by
retrieving for example idx_scan and friends in pg_stat_all_tables.
pg_stat_reset_single_table_counters() is supported for an index for a
long time, but the case was never covered.
This commit closes the gap, by using this reset function on an index,
cross-checking the contents of pg_stat_all_indexes.
Author: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Discussion: https://postgr.es/m/aN8l182jKxEq1h9f@paquier.xyz
On Windows, this code did not handle error conditions correctly at
all, since it looked at "errno" which is not used for socket-related
errors on that platform. This resulted, for example, in failure
to connect to a PostgreSQL server with GSSAPI enabled.
We have a convention for dealing with this within libpq, which is to
use SOCK_ERRNO and SOCK_ERRNO_SET rather than touching errno directly;
but the GSSAPI code is a relative latecomer and did not get that memo.
(The equivalent backend code continues to use errno, because the
backend does this differently. Maybe libpq's approach should be
rethought someday.)
Apparently nobody tries to build libpq with GSSAPI support on Windows,
or we'd have heard about this before, because it's been broken all
along. Back-patch to all supported branches.
Author: Ning Wu <ning94803@gmail.com>
Co-authored-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CAFGqpvg-pRw=cdsUpKYfwY6D3d-m9tw8WMcAEE7HHWfm-oYWvw@mail.gmail.com
Backpatch-through: 13
This adjusts UNION planning so that the planner produces more optimal
plans when one or more of the UNION's subqueries have been proven to be
empty (a dummy rel).
If any of the inputs are empty, then that input can be removed from the
Append / MergeAppend. Previously, a const-false "Result" node would
appear to represent this. Removing empty inputs has a few extra
benefits when only 1 union child remains as it means the Append or
MergeAppend can be removed in setrefs.c, making the plan slightly faster
to execute. Also, we can provide better n_distinct estimates by looking
at the sole remaining input rel's statistics.
Author: David Rowley <dgrowleyml@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CAApHDvri53PPF76c3M94_QNWbJfXjyCnjXuj_2=LYM-0m8WZtw@mail.gmail.com
bms_union() causes a new set to be allocated. What this caller needs is
members added to an existing set. bms_add_members() is the tool for
that job.
This is just a matter of fixing an inefficiency due to surplus memory
allocations. No bugs being fixed.
The only other place I found that might be valid to apply this change is
in markNullableIfNeeded(), but I opted not to do that due to the risk to
reward ratio not looking favorable. The risk being that there *could* be
another pointer pointing to the Bitmapset.
Author: David Rowley <dgrowleyml@gmail.com>
Reviewed-by: Greg Burd <greg@burd.me>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CAApHDvoCcoS-p5tZNJLTxFOKTYNjqVh7Dwf+5ikDUBwnvWftRw@mail.gmail.com
Presently, the SIMD implementation of this function uses unsigned
saturating subtraction to find bytes less than or equal to the
given value, which is a workaround for the lack of unsigned
comparison instructions on some architectures. However, Neon
offers vminvq_u8(), which returns the minimum (unsigned) value in
the vector. This commit adds a Neon-specific implementation that
uses vminvq_u8() to optimize vector8_has_le() on AArch64.
In passing, adjust the SSE2 implementation to use vector8_min() and
vector8_eq() to find values less than or equal to the given value.
This was the only use of vector8_ssub(), so it has been removed.
Reviewed-by: John Naylor <johncnaylorls@gmail.com>
Discussion: https://postgr.es/m/aNHDNDSHleq0ogC_%40nathan
Make some use of anonymous unions, which are allowed as of C11, as
examples and encouragement for future code, and to test compilers.
This commit changes the DSMRegistryEntry struct.
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Discussion: https://postgr.es/m/aNKsDg0fJwqhZdXX%40nathan
In similar vein to commit ccc8194e42, a reset instance of a shared
memory TID store happened to occupy the same private memory as the old
one for the entry point, since the chunk freed after the last round
of index vacuuming was put on the context's freelist. The failure
to update the vacrel->dead_items pointer was evident by nudging the
system to allocate memory in a different area. This was not discovered
at the time of the earlier commit since our regression tests didn't
cover multiple index passes with parallel vacuum.
Backpatch to v17, when TidStore came in.
Author: Kevin Oommen Anish <kevin.o@zohocorp.com>
Reviewed-by: Richard Guo <guofenglinux@gmail.com>
Tested-by: Richard Guo <guofenglinux@gmail.com>
Discussion: https://postgr.es/m/199a07cbdfc.7a1c4aac25838.1675074408277594551%40zohocorp.com
Backpatch-through: 17
Currently, pgbench aborts when a COPY response is received in
readCommandResponse(). However, as PQgetResult() returns an empty
result when there is no asynchronous result, through getCopyResult(),
the logic done at the end of readCommandResponse() for the error path
leads to an infinite loop.
This commit forcefully exits the COPY state with PQendcopy() before
moving to the error handler when fiding a COPY state, avoiding the
infinite loop. The COPY protocol is not supported by pgbench anyway, as
an error is assumed in this case, so giving up is better than having the
tool be stuck forever. pgbench was interruptible in this state.
A TAP test is added to check that an error happens if trying to use
COPY.
Author: Anthonin Bonnefoy <anthonin.bonnefoy@datadoghq.com>
Discussion: https://postgr.es/m/CAO6_XqpHyF2m73ifV5a=5jhXxH2chk=XrgefY+eWWPe2Eft3=A@mail.gmail.com
Backpatch-through: 13
Add IGNORE NULLS/RESPECT NULLS option (null treatment clause) to lead,
lag, first_value, last_value and nth_value window functions. If
unspecified, the default is RESPECT NULLS which includes NULL values
in any result calculation. IGNORE NULLS ignores NULL values.
Built-in window functions are modified to call new API
WinCheckAndInitializeNullTreatment() to indicate whether they accept
IGNORE NULLS/RESPECT NULLS option or not (the API can be called by
user defined window functions as well). If WinGetFuncArgInPartition's
allowNullTreatment argument is true and IGNORE NULLS option is given,
WinGetFuncArgInPartition() or WinGetFuncArgInFrame() will return
evaluated function's argument expression on specified non NULL row (if
it exists) in the partition or the frame.
When IGNORE NULLS option is given, window functions need to visit and
evaluate same rows over and over again to look for non null rows. To
mitigate the issue, 2-bit not null information array is created while
executing window functions to remember whether the row has been
already evaluated to NULL or NOT NULL. If already evaluated, we could
skip the evaluation work, thus we could get better performance.
Author: Oliver Ford <ojford@gmail.com>
Co-authored-by: Tatsuo Ishii <ishii@postgresql.org>
Reviewed-by: Krasiyan Andreev <krasiyan@gmail.com>
Reviewed-by: Andrew Gierth <andrew@tao11.riddles.org.uk>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: David Fetter <david@fetter.org>
Reviewed-by: Vik Fearing <vik@postgresfriends.org>
Reviewed-by: "David G. Johnston" <david.g.johnston@gmail.com>
Reviewed-by: Chao Li <lic@highgo.com>
Discussion: https://postgr.es/m/flat/CAGMVOdsbtRwE_4+v8zjH1d9xfovDeQAGLkP_B6k69_VoFEgX-A@mail.gmail.com
Move the checks out of the Makefile into a perl script that can be
called from both the Makefile and meson.build. The set of files checked
is simplified, so it is just all the sgml and xsl files found in
docs/src/sgml directory tree.
Along the way make some adjustments to .cirrus.tasks.yml to support this
better in CI.
Also ensure that the checks are part of the Makefile's html target.
Author: Nazir Bilal Yavuz <byavuz81@gmail.com>
Co-Author: Andrew Dunstan <andrew@dunslane.net>
Discussion: https://postgr.es/m/CAN55FZ3BnM+0twT-ZWL8As9oBEte_b+SBU==cz6Hk8JUCM_5Wg@mail.gmail.com
pgstattuple checks the state of the pages retrieved for gist and hash
using some check functions from each index AM, respectively
gistcheckpage() and _hash_checkpage(). When these are called, they
would fail when bumping on data that is found as incorrect (like opaque
area size not matching, or empty pages), contrary to btree that simply
discards these cases and continues to aggregate data.
Zero pages can happen after a crash, with these AMs being able to do an
internal cleanup when these are seen. Also, sporadic failures are
annoying when doing for example a large-scale diagnostic query based on
pgstattuple with a join of pg_class, as it forces one to use tricks like
quals to discard hash or gist indexes, or use a PL wrapper able to catch
errors.
This commit changes the reports generated for btree, gist and hash to
be more user-friendly;
- When seeing an empty page, report it as free space. This new rule
applies to gist and hash, and already applied to btree.
- For btree, a check based on the size of BTPageOpaqueData is added.
- For gist indexes, gistcheckpage() is not called anymore, replaced by a
check based on the size of GISTPageOpaqueData.
- For hash indexes, instead of _hash_getbuf_with_strategy(), use a
direct call to ReadBufferExtended(), coupled with a check based on
HashPageOpaqueData. The opaque area size check was already used.
- Pages that do not match these criterias are discarded from the stats
reports generated.
There have been a couple of bug reports over the years that complained
about the current behavior for hash and gist, as being not that useful,
with nothing being done about it. Hence this change is backpatched down
to v13.
Reported-by: Noah Misch <noah@leadboat.com>
Author: Nitin Motiani <nitinmotiani@google.com>
Reviewed-by: Dilip Kumar <dilipbalaut@gmail.com>
Discussion: https://postgr.es/m/CAH5HC95gT1J3dRYK4qEnaywG8RqjbwDdt04wuj8p39R=HukayA@mail.gmail.com
Backpatch-through: 13
Some macOS machines are having trouble with 002_inline, which executes
the JSON parser test executables hundreds of times in a nested loop.
Both developer machines and buildfarm critters have shown excessive test
durations, upwards of 20 seconds.
Push the innermost loop of 002_inline, which iterates through differing
chunk sizes, down into the test executable. (I'd eventually like to push
all of the JSON unit tests down into C, but this is an easy win in the
short term.) Testers have reported a speedup between 4-9x.
Reported-by: Robert Haas <robertmhaas@gmail.com>
Suggested-by: Andres Freund <andres@anarazel.de>
Tested-by: Andrew Dunstan <andrew@dunslane.net>
Tested-by: Tom Lane <tgl@sss.pgh.pa.us>
Tested-by: Robert Haas <robertmhaas@gmail.com>
Discussion: https://postgr.es/m/CA%2BTgmobKoG%2BgKzH9qB7uE4MFo-z1hn7UngqAe9b0UqNbn3_XGQ%40mail.gmail.com
Backpatch-through: 17
Newer compilers warned about
extern int _CRT_glob = 0;
which is indeed a mysterious C construction, as it combines "extern"
and an initialization. It turns out that according to the C standard,
the "extern" is ignored here, so we can remove it to resolve the
warnings. But then we also need to add a real extern
declaration (without initializer) to satisfy
-Wmissing-variable-declarations.
(Note that this code is only active on MinGW.)
Discussion: https://www.postgresql.org/message-id/1053279b-da01-4eb4-b7a3-da6b5d8f73d1%40eisentraut.org
Two macros are added in this module, to cut duplicated patterns:
- PG_ARG_GETBITMAPSET(), for input argument handling, with knowledge
about NULL.
- PG_RETURN_BITMAPSET_AS_TEXT(), that generates a text result from a
Bitmapset.
These changes limit the code so as the SQL functions are now mostly
wrappers of the equivalent C function. Functions that use integer input
arguments still need some NULL handling, like bms_make_singleton().
A NULL input is translated to "<>", which is what nodeToString()
generates. Some of the tests are able to generate this result.
Per discussion, the calls of bms_free() are removed. These may be
justified if the functions are used in a rather long-lived memory
context, but let's keep the code minimal for now. These calls used NULL
checks, which were also not necessary as NULL is an input authorized by
bms_free().
Some of the tests existed to cover behaviors related to the SQL
functions for NULL inputs. Most of them are still relevant, as the
routines of bitmapset.c are able to handle such cases.
The coverage reports of bitmapset.c and test_bitmapset.c remain the
same after these changes, with 300 lines of C code removed.
Author: David Rowley <dgrowleyml@gmail.com>
Co-authored-by: Greg Burd <greg@burd.me>
Discussion: https://postgr.es/m/CAApHDvqghMnm_zgSNefto9oaEJ0S-3Cgb3gdsV7XvLC-hMS02Q@mail.gmail.com
pgbench uses readCommandResponse() to process server responses.
When readCommandResponse() encounters an error during a call to
PQgetResult() to fetch the current result, it attempts to report it
with an additional error message from PQerrorMessage(). However,
previously, this extra error message could be lost or become incorrect.
The cause was that after fetching the current result (and detecting
an error), readCommandResponse() called PQgetResult() again to
peek at the next result. This second call could overwrite the libpq
connection's error message before the original error was reported,
causing the error message retrieved from PQerrorMessage() to be
lost or overwritten.
This commit fixes the issue by updating readCommandResponse()
to use PQresultErrorMessage() instead of PQerrorMessage()
to retrieve the error message generated when the PQgetResult()
for the current result causes an error, ensuring the correct message
is reported.
Backpatch to all supported versions.
Author: Yugo Nagata <nagata@sraoss.co.jp>
Reviewed-by: Chao Li <lic@highgo.com>
Reviewed-by: Fujii Masao <masao.fujii@gmail.com>
Discussion: https://postgr.es/m/20250925110940.ebacc31725758ec47d5432c6@sraoss.co.jp
Backpatch-through: 13
This reverts commit efcd5199d8.
I rebased my patch series incorrectly. This patch contained unrelated
parts from another patch, which made the overall build fail. Revert
for now and reconsider.
Stop including utils/relcache.h in access/genam.h, and stop including
htup_details.h in nodes/tidbitmap.h. Both these files (genam.h and
tidbitmap.h) are widely used in other header files, so it's in our best
interest that they remain as lean as reasonable.
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/202509291356.o5t6ny2hoa3q@alvherre.pgsql
During recovery, XLogNeedsFlush() checks the minimum recovery LSN point
instead of the flush LSN point. The same condition checks are used when
updating the minimum recovery point in UpdateMinRecoveryPoint(), but are
written in reverse order.
This commit makes the order of the checks consistent between
XLogNeedsFlush() and UpdateMinRecoveryPoint(), improving the code
clarity. Note that the second check (as ordered by this commit) relies
on InRecovery, which is true only in the startup process. So this makes
XLogNeedsFlush() cheaper in the startup process with the first check
acting as a shortcut while doing crash recovery, where
LocalMinRecoveryPoint is an invalid LSN.
Author: Melanie Plageman <melanieplageman@gmail.com>
Reviewed-by: Dilip Kumar <dilipbalaut@gmail.com>
Discussion: https://postgr.es/m/aMIHNRTP6Wj6vw1s%40paquier.xyz
Contrary to its siblings for the archiver, the bgwriter and the
checkpointer stats, pgstat_report_inj_fixed() can be called
concurrently. This was causing an assertion failure, while messing up
with the stats.
This code is aimed at being a template for extension developers, so it
is not a critical issue, but let's be correct. This module has also
been useful for some benchmarking, at least for me, and that was how I
have discovered this issue.
Oversight in f68cd847fa.
Author: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Reviewed-by: wenhui qiu <qiuwenhuifx@gmail.com>
Discussion: https://postgr.es/m/aNnXbAXHPFUWPIz2@paquier.xyz
Backpatch-through: 18
GROUP BY ALL is a form of GROUP BY that adds any TargetExpr that does
not contain an aggregate or window function into the groupClause of
the query, making it exactly equivalent to specifying those same
expressions in an explicit GROUP BY list.
This feature is useful for certain kinds of data exploration. It's
already present in some other DBMSes, and the SQL committee recently
accepted it into the standard, so we can be reasonably confident in
the syntax being stable. We do have to invent part of the semantics,
as the standard doesn't allow for expressions in GROUP BY, so they
haven't specified what to do with window functions. We assume that
those should be treated like aggregates, i.e., left out of the
constructed GROUP BY list.
In passing, wordsmith some existing documentation about GROUP BY,
and update some neglected synopsis entries in select_into.sgml.
Author: David Christensen <david@pgguru.net>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CAHM0NXjz0kDwtzoe-fnHAqPB1qA8_VJN0XAmCgUZ+iPnvP5LbA@mail.gmail.com
Neighbor get_statistics_object_oid() ignores objects in pg_temp, as has
been the standard for non-relation, non-type namespace searches since
CVE-2007-2138. Hence, most operations that name a statistics object
correctly decline to map an unqualified name to a statistics object in
pg_temp. StatisticsObjIsVisibleExt() did not. Consequently,
pg_statistics_obj_is_visible() wrongly returned true for such objects,
psql \dX wrongly listed them, and getObjectDescription()-based ereport()
and pg_describe_object() wrongly omitted namespace qualification. Any
malfunction beyond that would depend on how a human or application acts
on those wrong indications. Commit
d99d58cdc8 introduced this. Back-patch to
v13 (all supported versions).
Reviewed-by: Nathan Bossart <nathandbossart@gmail.com>
Discussion: https://postgr.es/m/20250920162116.2e.nmisch@google.com
Backpatch-through: 13
This commit expands the set of tests added by 00c3d87a5c, to bring the
coverage of bitmapset.c close to 100% by addressing a lot of corner
cases (most of these relate to word counts and reallocations).
Some of the functions of this module also have their own idea of the
result to return depending on the input values given. These are
specific to the module, still let's add more coverage for all of them.
Some comments are made more consistent in the tests, while on it.
Author: Greg Burd <greg@burd.me>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/aNR-gsGmLnMaNT5i@paquier.xyz
For UNION, EXCEPT and INTERSECT, we were not very good at estimating the
PathTarget.width for the set operation. Since the targetlist of the set
operation is made up of Vars with varno==0, this would result in
get_expr_width() applying a default estimate based on the Var's type
rather than taking width estimates from any relation's statistics.
Here we attempt to improve the situation by looking at the width estimates
for the set operation child paths and calculating the average width of the
relevant child paths weighted over the estimated number of rows. For
UNION and INTERSECT, the relevant paths to look at are *all* child paths.
For EXCEPT, since we don't return rows from the right-hand child (only
possibly remove left-hand rows matching those), we use only the left-hand
child for width estimates.
This also adjusts the hashed-UNION Path's PathTarget to use the same
PathTarget as its Append subpath. Both PathTargets will be the same and
are void of any resjunk columns, per generate_append_tlist(). Making
the AggPath use the same PathTarget saves having to adjust the "width"
of the AggPath's PathTarget too.
This was reported as a bug by sunw.fnst, but it's not something we ever
claimed to do properly. Plus, if we were to adjust this in back
branches, plans could change as the estimated input sizes to Sorts and
Hash Aggregates could go up or down. Plan choices aren't something we
want to destabilize in stable versions.
Reported-by: sunw.fnst <936739278@qq.com>
Author: David Rowley <drowleyml@gmail.com>
Discussion: https://postgr.es/m/tencent_34CF8017AB81944A4C08DD089D410AB6C306@qq.com
This serves as coverage for the tracking of entry count added by
7bd2975fa9 as built-in variable-sized stats kinds have no need for it,
at least not yet.
A new function, called injection_points_stats_count(), is added to the
module. It is able to return the number of entries. This has been
useful when doing some benchmarking to check the sanity of the counts.
Author: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Discussion: https://postgr.es/m/aMPKWR81KT5UXvEr@paquier.xyz
Stats kinds can set a new option called "track_entry_count" (disabled by
default, available for variable-numbered stats) that will make pgstats
track the number of entries that exist in its shared hashtable.
As there is only one code path where a new entry is added, and one code
path where entries are freed, the count tracking is straight-forward in
its implementation. Reads of these counters are optimistic, and may
change across two calls. The counter is incremented when an entry is
created (not when reused), and is decremented when an entry is freed
from the hashtable (marked for drop with its refcount reaching 0), which
is something that pgstats decides internally.
A first use case of this facility would be pg_stat_statements, where we
need to be able to cap the number of entries that would be stored in the
shared hashtable, based on its "max" GUC. The module currently relies
on hash_get_num_entries(), which offers a cheap way to count how many
entries are in its hash table, but we cannot do that in pgstats for
variable-sized stats kinds as a single hashtable is used for all the
stats kinds. Independently of PGSS, this is useful for other custom
stats kinds that want to cap, control, or track the number of entries
they have, without depending on a potentially expensive sequential scan
to know the number of entries while holding an extra exclusive lock.
Author: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Sami Imseih <samimseih@gmail.com>
Reviewed-by: Keisuke Kuroda <keisuke.kuroda.3862@gmail.com>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Discussion: https://postgr.es/m/aMPKWR81KT5UXvEr@paquier.xyz
transformPLAssignStmt contained many lines cribbed directly from
transformSelectStmt. I had supposed that we could manage to keep
the two copies in sync, but the bug just fixed in 7504d2be9 shows
that that hope was foolish. Let's refactor so there's just one copy.
The main stumbling block to doing this is that transformPLAssignStmt
has a chunk of custom code that has to run after transformTargetList
but before we potentially modify the tlist further during analysis
of ORDER BY and GROUP BY. Rather than make transformSelectStmt fully
aware of PLAssignStmt processing, I put that code into a callback
function. It still feels a little bit ugly, but it's not too awful,
and surely it's better than a hundred lines of duplicated code.
The steps involved in processing a PLAssignStmt remain exactly
the same as before, just in different places.
Author: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/31027.1758919078@sss.pgh.pa.us
