The original advice for hard-wired SetConfigOption calls was to use
PGC_S_OVERRIDE, particularly for PGC_INTERNAL GUCs. However,
that's really overkill for PGC_INTERNAL GUCs, since there is no
possibility that we need to override a user-provided setting.
Instead use PGC_S_DYNAMIC_DEFAULT in most places, so that the
value will appear with source = 'default' in pg_settings and thereby
not be shown by psql's new \dconfig command. The one exception is
that when changing in_hot_standby in a hot-standby session, we still
use PGC_S_OVERRIDE, because people felt that seeing that in \dconfig
would be a good thing.
Similarly use PGC_S_DYNAMIC_DEFAULT for the auto-tune value of
wal_buffers (if possible, that is if wal_buffers wasn't explicitly
set to -1), and for the typical 2MB value of max_stack_depth.
In combination these changes remove four not-very-interesting
entries from the typical output of \dconfig, all of which people
fingered as "why is that showing up?" in the discussion thread.
Discussion: https://postgr.es/m/3118455.1649267333@sss.pgh.pa.us
697492434 added 3 new quicksort specialization functions for common
datatypes.
That commit was not very consistent in how it would determine if we're
compiling for 32-bit or 64-bit machines. It would sometimes use
USE_FLOAT8_BYVAL and at other times check if SIZEOF_DATUM == 8. This
could cause theoretical problems due to the way USE_FLOAT8_BYVAL is now
defined based on SIZEOF_VOID_P >= 8. If pointers for some reason were
ever larger than 8-bytes then we'd end up doing 32-bit comparisons
mistakenly. Let's just always check SIZEOF_DATUM >= 8.
It also seems that ssup_datum_signed_cmp is just never used on 32-bit
builds, so let's just ifdef that out to make sure we never accidentally
use that comparison function on such machines. This also allows us to
ifdef out 1 of the 3 new specialization quicksort functions in 32-bit
builds which seems to shrink down the binary by over 4KB on my machine.
In passing, also add the missing DatumGetInt32() / DatumGetInt64() macros
in the comparison functions.
Discussion: https://postgr.es/m/CAApHDvqcQExRhtRa9hJrJB_5egs3SUfOcutP3m+3HO8A+fZTPA@mail.gmail.com
Reviewed-by: John Naylor
Up until now, we've had a policy of only marking certain variables
in the PostgreSQL header files with PGDLLIMPORT, but now we've
decided to mark them all. This means that extensions running on
Windows should no longer operate at a disadvantage as compared to
extensions running on Linux: if the variable is present in a header
file, it should be accessible.
Discussion: http://postgr.es/m/CA+TgmoYanc1_FSfimhgiWSqVyP5KKmh5NP2BWNwDhO8Pg2vGYQ@mail.gmail.com
Introduce a new GUC recovery_prefetch. When enabled, look ahead in the
WAL and try to initiate asynchronous reading of referenced data blocks
that are not yet cached in our buffer pool. For now, this is done with
posix_fadvise(), which has several caveats. Since not all OSes have
that system call, "try" is provided so that it can be enabled where
available. Better mechanisms for asynchronous I/O are possible in later
work.
Set to "try" for now for test coverage. Default setting to be finalized
before release.
The GUC wal_decode_buffer_size limits the distance we can look ahead in
bytes of decoded data.
The existing GUC maintenance_io_concurrency is used to limit the number
of concurrent I/Os allowed, based on pessimistic heuristics used to
infer that I/Os have begun and completed. We'll also not look more than
maintenance_io_concurrency * 4 block references ahead.
Reviewed-by: Julien Rouhaud <rjuju123@gmail.com>
Reviewed-by: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Reviewed-by: Alvaro Herrera <alvherre@2ndquadrant.com> (earlier version)
Reviewed-by: Andres Freund <andres@anarazel.de> (earlier version)
Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> (earlier version)
Tested-by: Tomas Vondra <tomas.vondra@2ndquadrant.com> (earlier version)
Tested-by: Jakub Wartak <Jakub.Wartak@tomtom.com> (earlier version)
Tested-by: Dmitry Dolgov <9erthalion6@gmail.com> (earlier version)
Tested-by: Sait Talha Nisanci <Sait.Nisanci@microsoft.com> (earlier version)
Discussion: https://postgr.es/m/CA%2BhUKGJ4VJN8ttxScUFM8dOKX0BrBiboo5uz1cq%3DAovOddfHpA%40mail.gmail.com
Allow extensions to specify a new custom resource manager (rmgr),
which allows specialized WAL. This is meant to be used by a Table
Access Method or Index Access Method.
Prior to this commit, only Generic WAL was available, which offers
support for recovery and physical replication but not logical
replication.
Reviewed-by: Julien Rouhaud, Bharath Rupireddy, Andres Freund
Discussion: https://postgr.es/m/ed1fb2e22d15d3563ae0eb610f7b61bb15999c0a.camel%40j-davis.com
Previously the statistics collector received statistics updates via UDP and
shared statistics data by writing them out to temporary files regularly. These
files can reach tens of megabytes and are written out up to twice a
second. This has repeatedly prevented us from adding additional useful
statistics.
Now statistics are stored in shared memory. Statistics for variable-numbered
objects are stored in a dshash hashtable (backed by dynamic shared
memory). Fixed-numbered stats are stored in plain shared memory.
The header for pgstat.c contains an overview of the architecture.
The stats collector is not needed anymore, remove it.
By utilizing the transactional statistics drop infrastructure introduced in a
prior commit statistics entries cannot "leak" anymore. Previously leaked
statistics were dropped by pgstat_vacuum_stat(), called from [auto-]vacuum. On
systems with many small relations pgstat_vacuum_stat() could be quite
expensive.
Now that replicas drop statistics entries for dropped objects, it is not
necessary anymore to reset stats when starting from a cleanly shut down
replica.
Subsequent commits will perform some further code cleanup, adapt docs and add
tests.
Bumps PGSTAT_FILE_FORMAT_ID.
Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Author: Andres Freund <andres@anarazel.de>
Author: Melanie Plageman <melanieplageman@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Thomas Munro <thomas.munro@gmail.com>
Reviewed-By: Justin Pryzby <pryzby@telsasoft.com>
Reviewed-By: "David G. Johnston" <david.g.johnston@gmail.com>
Reviewed-By: Tomas Vondra <tomas.vondra@2ndquadrant.com> (in a much earlier version)
Reviewed-By: Arthur Zakirov <a.zakirov@postgrespro.ru> (in a much earlier version)
Reviewed-By: Antonin Houska <ah@cybertec.at> (in a much earlier version)
Discussion: https://postgr.es/m/20220303021600.hs34ghqcw6zcokdh@alap3.anarazel.de
Discussion: https://postgr.es/m/20220308205351.2xcn6k4x5yivcxyd@alap3.anarazel.de
Discussion: https://postgr.es/m/20210319235115.y3wz7hpnnrshdyv6@alap3.anarazel.de
Most of pgstat uses pgstat_<verb>_<subject>() or just <verb>_<subject>(). But
not all (some introduced fairly recently by me). Rename ones that aren't
intentionally following a different scheme (e.g. AtEOXact_*).
One problematic part of the current statistics collector design is that there
is no reliable way of getting rid of statistics entries. Because of that
pgstat_vacuum_stat() (called by [auto-]vacuum) matches all stats for the
current database with the catalog contents and tries to drop now-superfluous
entries. That's quite expensive. What's worse, it doesn't work on physical
replicas, despite physical replicas collection statistics entries.
This commit introduces infrastructure to create / drop statistics entries
transactionally, together with the underlying catalog objects (functions,
relations, subscriptions). pgstat_xact.c maintains a list of stats entries
created / dropped transactionally in the current transaction. To ensure the
removal of statistics entries is durable dropped statistics entries are
included in commit / abort (and prepare) records, which also ensures that
stats entries are dropped on standbys.
Statistics entries created separately from creating the underlying catalog
object (e.g. when stats were previously lost due to an immediate restart)
are *not* WAL logged. However that can only happen outside of the transaction
creating the catalog object, so it does not lead to "leaked" statistics
entries.
For this to work, functions creating / dropping functions / relations /
subscriptions need to call into pgstat. For subscriptions this was already
done when dropping subscriptions, via pgstat_report_subscription_drop() (now
renamed to pgstat_drop_subscription()).
This commit does not actually drop stats yet, it just provides the
infrastructure. It is however a largely independent piece of infrastructure,
so committing it separately makes sense.
Bumps XLOG_PAGE_MAGIC.
Author: Andres Freund <andres@anarazel.de>
Reviewed-By: Thomas Munro <thomas.munro@gmail.com>
Reviewed-By: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Discussion: https://postgr.es/m/20220303021600.hs34ghqcw6zcokdh@alap3.anarazel.de
Soon the stats collector will be no more, with statistics instead getting
stored in shared memory. There are a lot of references to the stats collector
in comments. This commit replaces most of these references with "cumulative
statistics system", with the remaining ones getting replaced as part of
subsequent commits.
This is done separately from the - quite large - shared memory statistics
patch to make review easier.
Author: Andres Freund <andres@anarazel.de>
Reviewed-By: Justin Pryzby <pryzby@telsasoft.com>
Reviewed-By: Thomas Munro <thomas.munro@gmail.com>
Reviewed-By: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Discussion: https://postgr.es/m/20220303021600.hs34ghqcw6zcokdh@alap3.anarazel.de
Discussion: https://postgr.es/m/20220308205351.2xcn6k4x5yivcxyd@alap3.anarazel.de
The transactional integration code is largely independent from the rest of
pgstat.c. Subsequent commits will add more related code.
Author: Andres Freund <andres@anarazel.de>
Reviewed-By: Thomas Munro <thomas.munro@gmail.com>
Discussion: https://postgr.es/m/20220404041516.cctrvpadhuriawlq@alap3.anarazel.de
This patch allows "PGC_SUSET" parameters to be set by non-superusers
if they have been explicitly granted the privilege to do so.
The privilege to perform ALTER SYSTEM SET/RESET on a specific parameter
can also be granted.
Such privileges are cluster-wide, not per database. They are tracked
in a new shared catalog, pg_parameter_acl.
Granting and revoking these new privileges works as one would expect.
One caveat is that PGC_USERSET GUCs are unaffected by the SET privilege
--- one could wish that those were handled by a revocable grant to
PUBLIC, but they are not, because we couldn't make it robust enough
for GUCs defined by extensions.
Mark Dilger, reviewed at various times by Andrew Dunstan, Robert Haas,
Joshua Brindle, and myself
Discussion: https://postgr.es/m/3D691E20-C1D5-4B80-8BA5-6BEB63AF3029@enterprisedb.com
This feature allows jsonb data to be treated as a table and thus used in
a FROM clause like other tabular data. Data can be selected from the
jsonb using jsonpath expressions, and hoisted out of nested structures
in the jsonb to form multiple rows, more or less like an outer join.
Nikita Glukhov
Reviewers have included (in no particular order) Andres Freund, Alexander
Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zhihong Yu (whose
name I previously misspelled), Himanshu Upadhyaya, Daniel Gustafsson,
Justin Pryzby.
Discussion: https://postgr.es/m/7e2cb85d-24cf-4abb-30a5-1a33715959bd@postgrespro.ru
The general usage pattern when we store tuples in tuplesort.c is that
we store a series of tuples one by one then either perform a sort or spill
them to disk. In the common case, there is no pfreeing of already stored
tuples. For the common case since we do not individually pfree tuples, we
have very little need for aset.c memory allocation behavior which
maintains freelists and always rounds allocation sizes up to the next
power of 2 size.
Here we conditionally use generation.c contexts for storing tuples in
tuplesort.c when the sort will never be bounded. Unfortunately, the
memory context to store tuples is already created by the time any calls
would be made to tuplesort_set_bound(), so here we add a new sort option
that allows callers to specify if they're going to need a bounded sort or
not. We'll use a standard aset.c allocator when this sort option is not
set.
Extension authors must ensure that the TUPLESORT_ALLOWBOUNDED flag is
used when calling tuplesort_begin_* for any sorts that make a call to
tuplesort_set_bound().
Author: David Rowley
Reviewed-by: Andy Fan
Discussion: https://postgr.es/m/CAApHDvoH4ASzsAOyHcxkuY01Qf++8JJ0paw+03dk+W25tQEcNQ@mail.gmail.com
This replaces the bool flag for randomAccess. An upcoming patch requires
adding another option, so instead of breaking the API for that, then
breaking it again one day if we add more options, let's just break it
once. Any boolean options we add in the future will just make use of an
unused bit in the flags.
Any extensions making use of tuplesorts will need to update their code
to pass TUPLESORT_RANDOMACCESS instead of true for randomAccess.
TUPLESORT_NONE can be used for a set of empty options.
Author: David Rowley
Reviewed-by: Justin Pryzby
Discussion: https://postgr.es/m/CAApHDvoH4ASzsAOyHcxkuY01Qf%2B%2B8JJ0paw%2B03dk%2BW25tQEcNQ%40mail.gmail.com
Here we make a series of improvements to the generation memory
allocator, namely:
1. Allow generation contexts to have a minimum, initial and maximum block
sizes. The standard allocator allows this already but when the generation
context was added, it only allowed fixed-sized blocks. The problem with
fixed-sized blocks is that it's difficult to choose how large to make the
blocks. If the chosen size is too small then we'd end up with a large
number of blocks and a large number of malloc calls. If the block size is
made too large, then memory is wasted.
2. Add support for "keeper" blocks. This is a special block that is
allocated along with the context itself but is never freed. Instead,
when the last chunk in the keeper block is freed, we simply mark the block
as empty to allow new allocations to make use of it.
3. Add facility to "recycle" newly empty blocks instead of freeing them
and having to later malloc an entire new block again. We do this by
recording a single GenerationBlock which has become empty of any chunks.
When we run out of space in the current block, we check to see if there is
a "freeblock" and use that if it contains enough space for the allocation.
Author: David Rowley, Tomas Vondra
Reviewed-by: Andy Fan
Discussion: https://postgr.es/m/d987fd54-01f8-0f73-af6c-519f799a0ab8@enterprisedb.com
DecodeInterval (interval input) was careless about integer-overflow
hazards, allowing bogus results to be obtained for sufficiently
large input values. Also, since it initially converted the input
to a "struct tm", it was impossible to produce the full range of
representable interval values.
Meanwhile, EncodeInterval (interval output) and a few other
functions could suffer failures if asked to process sufficiently
large interval values, because they also relied on being able to
represent an interval in "struct tm" which is not designed to
handle that.
Fix all this stuff by introducing new struct types that are more
fit for purpose.
While this is clearly a bug fix, it's also an API break for any
code that's calling these functions directly. So back-patching
doesn't seem wise, especially in view of the lack of field
complaints.
Joe Koshakow, editorialized a bit by me
Discussion: https://postgr.es/m/CAAvxfHff0JLYHwyBrtMx_=6wr=k2Xp+D+-X3vEhHjJYMj+mQcg@mail.gmail.com
Previously, the specialized tuplesort routine inlined handling for
reverse-sort and NULLs-ordering but called the datum comparator via a
pointer in the SortSupport struct parameter. Testing has showed that we
can get a useful performance gain by specializing datum comparison for
the different representations of abbreviated keys -- signed and unsigned
64-bit integers and signed 32-bit integers. Almost all abbreviatable data
types will benefit -- the only exception for now is numeric, since the
datum comparison is more complex. The performance gain depends on data
type and input distribution, but often falls in the range of 10-20% faster.
Thomas Munro
Reviewed by Peter Geoghegan, review and performance testing by me
Discussion:
https://www.postgresql.org/message-id/CA%2BhUKGKKYttZZk-JMRQSVak%3DCXSJ5fiwtirFf%3Dn%3DPAbumvn1Ww%40mail.gmail.com
When evaluating a query with a multi-column GROUP BY clause using sort,
the cost may be heavily dependent on the order in which the keys are
compared when building the groups. Grouping does not imply any ordering,
so we're allowed to compare the keys in arbitrary order, and a Hash Agg
leverages this. But for Group Agg, we simply compared keys in the order
as specified in the query. This commit explores alternative ordering of
the keys, trying to find a cheaper one.
In principle, we might generate grouping paths for all permutations of
the keys, and leave the rest to the optimizer. But that might get very
expensive, so we try to pick only a couple interesting orderings based
on both local and global information.
When planning the grouping path, we explore statistics (number of
distinct values, cost of the comparison function) for the keys and
reorder them to minimize comparison costs. Intuitively, it may be better
to perform more expensive comparisons (for complex data types etc.)
last, because maybe the cheaper comparisons will be enough. Similarly,
the higher the cardinality of a key, the lower the probability we’ll
need to compare more keys. The patch generates and costs various
orderings, picking the cheapest ones.
The ordering of group keys may interact with other parts of the query,
some of which may not be known while planning the grouping. E.g. there
may be an explicit ORDER BY clause, or some other ordering-dependent
operation, higher up in the query, and using the same ordering may allow
using either incremental sort or even eliminate the sort entirely.
The patch generates orderings and picks those minimizing the comparison
cost (for various pathkeys), and then adds orderings that might be
useful for operations higher up in the plan (ORDER BY, etc.). Finally,
it always keeps the ordering specified in the query, on the assumption
the user might have additional insights.
This introduces a new GUC enable_group_by_reordering, so that the
optimization may be disabled if needed.
The original patch was proposed by Teodor Sigaev, and later improved and
reworked by Dmitry Dolgov. Reviews by a number of people, including me,
Andrey Lepikhov, Claudio Freire, Ibrar Ahmed and Zhihong Yu.
Author: Dmitry Dolgov, Teodor Sigaev, Tomas Vondra
Reviewed-by: Tomas Vondra, Andrey Lepikhov, Claudio Freire, Ibrar Ahmed, Zhihong Yu
Discussion: https://postgr.es/m/7c79e6a5-8597-74e8-0671-1c39d124c9d6%40sigaev.ru
Discussion: https://postgr.es/m/CA%2Bq6zcW_4o2NC0zutLkOJPsFt80megSpX_dVRo6GK9PC-Jx_Ag%40mail.gmail.com
This Patch introduces three SQL standard JSON functions:
JSON() (incorrectly mentioned in my commit message for f4fb45d15c)
JSON_SCALAR()
JSON_SERIALIZE()
JSON() produces json values from text, bytea, json or jsonb values, and
has facilitites for handling duplicate keys.
JSON_SCALAR() produces a json value from any scalar sql value, including
json and jsonb.
JSON_SERIALIZE() produces text or bytea from input which containis or
represents json or jsonb;
For the most part these functions don't add any significant new
capabilities, but they will be of use to users wanting standard
compliant JSON handling.
Nikita Glukhov
Reviewers have included (in no particular order) Andres Freund, Alexander
Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zihong Yu,
Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby.
Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru
This introduces the SQL/JSON functions for querying JSON data using
jsonpath expressions. The functions are:
JSON_EXISTS()
JSON_QUERY()
JSON_VALUE()
All of these functions only operate on jsonb. The workaround for now is
to cast the argument to jsonb.
JSON_EXISTS() tests if the jsonpath expression applied to the jsonb
value yields any values. JSON_VALUE() must return a single value, and an
error occurs if it tries to return multiple values. JSON_QUERY() must
return a json object or array, and there are various WRAPPER options for
handling scalar or multi-value results. Both these functions have
options for handling EMPTY and ERROR conditions.
Nikita Glukhov
Reviewers have included (in no particular order) Andres Freund, Alexander
Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zihong Yu,
Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby.
Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru
Because this strategy logs changes on a block-by-block basis, it
avoids the need to checkpoint before and after the operation.
However, because it logs each changed block individually, it might
generate a lot of extra write-ahead logging if the template database
is large. Therefore, the older strategy remains available via a new
STRATEGY parameter to CREATE DATABASE, and a corresponding --strategy
option to createdb.
Somewhat controversially, this patch assembles the list of relations
to be copied to the new database by reading the pg_class relation of
the template database. Cross-database access like this isn't normally
possible, but it can be made to work here because there can't be any
connections to the database being copied, nor can it contain any
in-doubt transactions. Even so, we have to use lower-level interfaces
than normal, since the table scan and relcache interfaces will not
work for a database to which we're not connected. The advantage of
this approach is that we do not need to rely on the filesystem to
determine what ought to be copied, but instead on PostgreSQL's own
knowledge of the database structure. This avoids, for example,
copying stray files that happen to be located in the source database
directory.
Dilip Kumar, with a fairly large number of cosmetic changes by me.
Reviewed and tested by Ashutosh Sharma, Andres Freund, John Naylor,
Greg Nancarrow, Neha Sharma. Additional feedback from Bruce Momjian,
Heikki Linnakangas, Julien Rouhaud, Adam Brusselback, Kyotaro
Horiguchi, Tomas Vondra, Andrew Dunstan, Álvaro Herrera, and others.
Discussion: http://postgr.es/m/CA+TgmoYtcdxBjLh31DLxUXHxFVMPGzrU5_T=CYCvRyFHywSBUQ@mail.gmail.com
This patch intrdocuces the SQL standard IS JSON predicate. It operates
on text and bytea values representing JSON as well as on the json and
jsonb types. Each test has an IS and IS NOT variant. The tests are:
IS JSON [VALUE]
IS JSON ARRAY
IS JSON OBJECT
IS JSON SCALAR
IS JSON WITH | WITHOUT UNIQUE KEYS
These are mostly self-explanatory, but note that IS JSON WITHOUT UNIQUE
KEYS is true whenever IS JSON is true, and IS JSON WITH UNIQUE KEYS is
true whenever IS JSON is true except it IS JSON OBJECT is true and there
are duplicate keys (which is never the case when applied to jsonb values).
Nikita Glukhov
Reviewers have included (in no particular order) Andres Freund, Alexander
Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zihong Yu,
Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby.
Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru
This has no in-core callers but will be wanted by extensions.
It's just a thin wrapper around get_query_def, so it adds little code.
Also, fix get_from_clause_item() to force insertion of an alias
for a SUBQUERY RTE item. This is irrelevant to existing uses because
RTE_SUBQUERY items made by the parser always have aliases already.
However, if one tried to use pg_get_querydef() to inspect a post-rewrite
Query, it could be an issue. In any case, get_from_clause_item already
contained logic to force alias insertion for VALUES items, so the lack
of the same for SUBQUERY is a pretty clear oversight.
In passing, replace duplicated code for selection of pretty-print
options with a common macro.
Julien Rouhaud, reviewed by Pavel Stehule, Gilles Darold, and myself
Discussion: https://postgr.es/m/20210627041138.zklczwmu3ms4ufnk@nol
This patch introduces the SQL/JSON standard constructors for JSON:
JSON()
JSON_ARRAY()
JSON_ARRAYAGG()
JSON_OBJECT()
JSON_OBJECTAGG()
For the most part these functions provide facilities that mimic
existing json/jsonb functions. However, they also offer some useful
additional functionality. In addition to text input, the JSON() function
accepts bytea input, which it will decode and constuct a json value from.
The other functions provide useful options for handling duplicate keys
and null values.
This series of patches will be followed by a consolidated documentation
patch.
Nikita Glukhov
Reviewers have included (in no particular order) Andres Freund, Alexander
Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zihong Yu,
Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby.
Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru
clang 13 with -Wextra warns that "performing pointer subtraction with
a null pointer has undefined behavior" in the places where freepage.c
tries to set a relptr variable to constant NULL. This appears to be
a compiler bug, but it's unlikely to get fixed instantly. Fortunately,
we can work around it by introducing an inline support function, which
seems like a good change anyway because it removes the macro's existing
double-evaluation hazard.
Backpatch to v10 where this code was introduced.
Patch by me, based on an idea of Andres Freund's.
Discussion: https://postgr.es/m/48826.1648310694@sss.pgh.pa.us
A security invoker view checks permissions for accessing its
underlying base relations using the privileges of the user of the
view, rather than the privileges of the view owner. Additionally, if
any of the base relations are tables with RLS enabled, the policies of
the user of the view are applied, rather than those of the view owner.
This allows views to be defined without giving away additional
privileges on the underlying base relations, and matches a similar
feature available in other database systems.
It also allows views to operate more naturally with RLS, without
affecting the assignments of policies to users.
Christoph Heiss, with some additional hacking by me. Reviewed by
Laurenz Albe and Wolfgang Walther.
Discussion: https://postgr.es/m/b66dd6d6-ad3e-c6f2-8b90-47be773da240%40cybertec.at
pgstat.c is very long, and it's hard to find an order that makes sense and is
likely to be maintained over time. Splitting the different pieces into
separate files makes that a lot easier.
With a few exceptions, this commit just moves code around. Those exceptions
are:
- adding file headers for new files
- removing 'static' from functions
- adapting pgstat_assert_is_up() to work across TUs
- minor comment adjustments
git diff --color-moved=dimmed-zebra is very helpful separating code movement
from code changes.
The next commit in this series will reorder pgstat.[ch] contents to be a bit
more coherent.
Earlier revisions of this patch had "global" statistics (archiver, bgwriter,
checkpointer, replication slots, SLRU, WAL) in one file, because each seemed
small enough. However later commits will increase their size and their
aggregate size is not insubstantial. It also just seems easier to split each
type of statistic into its own file.
Author: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/20220303021600.hs34ghqcw6zcokdh@alap3.anarazel.de
createdb() didn't check for collation attributes validity, which has
to be done explicitly on ICU < 54. It also forgot to close the ICU collator
opened during the check which leaks some memory.
To fix both, add a new check_icu_locale() that does all the appropriate
verification and close the ICU collator.
initdb also had some partial check for ICU < 54. To have consistent error
reporting across major ICU versions, and get rid of the need to include ucol.h,
remove the partial check there. The backend will report an error if needed
during the post-boostrap iniitialization phase.
Author: Julien Rouhaud <julien.rouhaud@free.fr>
Discussion: https://www.postgresql.org/message-id/20220319041459.qqqiqh335sga5ezj@jrouhaud
This adds the option to use ICU as the default locale provider for
either the whole cluster or a database. New options for initdb,
createdb, and CREATE DATABASE are used to select this.
Since some (legacy) code still uses the libc locale facilities
directly, we still need to set the libc global locale settings even if
ICU is otherwise selected. So pg_database now has three
locale-related fields: the existing datcollate and datctype, which are
always set, and a new daticulocale, which is only set if ICU is
selected. A similar change is made in pg_collation for consistency,
but in that case, only the libc-related fields or the ICU-related
field is set, never both.
Reviewed-by: Julien Rouhaud <rjuju123@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/5e756dd6-0e91-d778-96fd-b1bcb06c161a%402ndquadrant.com
If we run out of space in the checkpointer sync request queue (which is
hopefully rare on real systems, but common with very small buffer pool),
we wait for it to drain. While waiting, we should report that as a wait
event so that users know what is going on, and also handle postmaster
death, since otherwise the loop might never terminate if the
checkpointer has exited.
Back-patch to 12. Although the problem exists in earlier releases too,
the code is structured differently before 12 so I haven't gone any
further for now, in the absence of field complaints.
Reported-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/20220226213942.nb7uvb2pamyu26dj%40alap3.anarazel.de
The checkpointer shouldn't ignore its latch. Other backends may be
waiting for it to drain the request queue. Hopefully real systems don't
have a full queue often, but the condition is reached easily when
shared_buffers is small.
This involves defining a new wait event, which will appear in the
pg_stat_activity view often due to spread checkpoints.
Back-patch only to 14. Even though the problem exists in earlier
branches too, it's hard to hit there. In 14 we stopped using signal
handlers for latches on Linux, *BSD and macOS, which were previously
hiding this problem by interrupting the sleep (though not reliably, as
the signal could arrive before the sleep begins; precisely the problem
latches address).
Reported-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/20220226213942.nb7uvb2pamyu26dj%40alap3.anarazel.de
This feature adds row filtering for publication tables. When a publication
is defined or modified, an optional WHERE clause can be specified. Rows
that don't satisfy this WHERE clause will be filtered out. This allows a
set of tables to be partially replicated. The row filter is per table. A
new row filter can be added simply by specifying a WHERE clause after the
table name. The WHERE clause must be enclosed by parentheses.
The row filter WHERE clause for a table added to a publication that
publishes UPDATE and/or DELETE operations must contain only columns that
are covered by REPLICA IDENTITY. The row filter WHERE clause for a table
added to a publication that publishes INSERT can use any column. If the
row filter evaluates to NULL, it is regarded as "false". The WHERE clause
only allows simple expressions that don't have user-defined functions,
user-defined operators, user-defined types, user-defined collations,
non-immutable built-in functions, or references to system columns. These
restrictions could be addressed in the future.
If you choose to do the initial table synchronization, only data that
satisfies the row filters is copied to the subscriber. If the subscription
has several publications in which a table has been published with
different WHERE clauses, rows that satisfy ANY of the expressions will be
copied. If a subscriber is a pre-15 version, the initial table
synchronization won't use row filters even if they are defined in the
publisher.
The row filters are applied before publishing the changes. If the
subscription has several publications in which the same table has been
published with different filters (for the same publish operation), those
expressions get OR'ed together so that rows satisfying any of the
expressions will be replicated.
This means all the other filters become redundant if (a) one of the
publications have no filter at all, (b) one of the publications was
created using FOR ALL TABLES, (c) one of the publications was created
using FOR ALL TABLES IN SCHEMA and the table belongs to that same schema.
If your publication contains a partitioned table, the publication
parameter publish_via_partition_root determines if it uses the partition's
row filter (if the parameter is false, the default) or the root
partitioned table's row filter.
Psql commands \dRp+ and \d <table-name> will display any row filters.
Author: Hou Zhijie, Euler Taveira, Peter Smith, Ajin Cherian
Reviewed-by: Greg Nancarrow, Haiying Tang, Amit Kapila, Tomas Vondra, Dilip Kumar, Vignesh C, Alvaro Herrera, Andres Freund, Wei Wang
Discussion: https://www.postgresql.org/message-id/flat/CAHE3wggb715X%2BmK_DitLXF25B%3DjE6xyNCH4YOwM860JR7HarGQ%40mail.gmail.com
"regress" is a new mode added to compute_query_id aimed at facilitating
regression testing when a module computing query IDs is loaded into the
backend, like pg_stat_statements. It works the same way as "auto",
meaning that query IDs are computed if a module enables it, except that
query IDs are hidden in EXPLAIN outputs to ensure regression output
stability.
Like any GUCs of the kind (force_parallel_mode, etc.), this new
configuration can be added to an instance's postgresql.conf, or just
passed down with PGOPTIONS at command level. compute_query_id uses an
enum for its set of option values, meaning that this addition ensures
ABI compatibility.
Using this new configuration mode allows installcheck-world to pass when
running the tests on an instance with pg_stat_statements enabled,
stabilizing the test output while checking the paths doing query ID
computations.
Reported-by: Anton Melnikov
Reviewed-by: Julien Rouhaud
Discussion: https://postgr.es/m/1634283396.372373993@f75.i.mail.ru
Discussion: https://postgr.es/m/YgHlxgc/OimuPYhH@paquier.xyz
Backpatch-through: 14
Commit 75d22069e tried to throw a warning for setting a custom GUC whose
prefix belongs to a previously-loaded extension, if there is no such GUC
defined by the extension. But that caused unstable behavior with
parallel workers, because workers don't necessarily load extensions and
GUCs in the same order their leader did. To make that work safely, we
have to completely disallow the case. We now actually remove any such
GUCs at the time of initial extension load, and then throw an error not
just a warning if you try to add one later. While this might create a
compatibility issue for a few people, the improvement in error-detection
capability seems worth it; it's hard to believe that there's any good
use-case for choosing such GUC names.
This also un-reverts 5609cc01c (Rename EmitWarningsOnPlaceholders() to
MarkGUCPrefixReserved()), since that function's old name is now even
more of a misnomer.
Florin Irion and Tom Lane
Discussion: https://postgr.es/m/1902182.1640711215@sss.pgh.pa.us
Commit <FIXME> fixed the bug that RemoveTempRelationsCallback() did not
push/register a snapshot. That only went unnoticed because often a valid
catalog snapshot exists and is returned by GetOldestSnapshot(). But due to
invalidation processing that is not reliable.
Thus assert in init_toast_snapshot() that there is a registered or active
snapshot, using the new HaveRegisteredOrActiveSnapshot().
Author: Andres Freund
Discussion: https://postgr.es/m/20220219180002.6tubjq7iw7m52bgd@alap3.anarazel.de
Commit 6e0cb3dec1 allowed postgres_fdw.application_name to include
escape sequences %a (application name), %d (database name), %u (user name)
and %p (pid). In addition to them, this commit makes it support
the escape sequences for session ID (%c) and cluster name (%C).
These are helpful to investigate where each remote transactions came from.
Author: Fujii Masao
Reviewed-by: Ryohei Takahashi, Kyotaro Horiguchi
Discussion: https://postgr.es/m/1041dc9a-c976-049f-9f14-e7d94c29c4b2@oss.nttdata.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
Move scanint8() to numutils.c and rename to pg_strtoint64(). We
already have a "16" and "32" version of that, and the code inside the
functions was aligned, so this move makes all three versions
consistent. The API is also changed to no longer provide the errorOK
case. Users that need the error checking can use strtoi64().
Reviewed-by: John Naylor <john.naylor@enterprisedb.com>
Discussion: https://www.postgresql.org/message-id/flat/b239564c-cad0-b23e-c57e-166d883cb97d@enterprisedb.com
The SQL standard has been ambiguous about whether null values in
unique constraints should be considered equal or not. Different
implementations have different behaviors. In the SQL:202x draft, this
has been formalized by making this implementation-defined and adding
an option on unique constraint definitions UNIQUE [ NULLS [NOT]
DISTINCT ] to choose a behavior explicitly.
This patch adds this option to PostgreSQL. The default behavior
remains UNIQUE NULLS DISTINCT. Making this happen in the btree code
is pretty easy; most of the patch is just to carry the flag around to
all the places that need it.
The CREATE UNIQUE INDEX syntax extension is not from the standard,
it's my own invention.
I named all the internal flags, catalog columns, etc. in the negative
("nulls not distinct") so that the default PostgreSQL behavior is the
default if the flag is false.
Reviewed-by: Maxim Orlov <orlovmg@gmail.com>
Reviewed-by: Pavel Borisov <pashkin.elfe@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/84e5ee1b-387e-9a54-c326-9082674bde78@enterprisedb.com
Commit 8431e296ea reworked ProcArrayApplyRecoveryInfo to sort XIDs
before adding them to KnownAssignedXids. But the XIDs are sorted using
xidComparator, which compares the XIDs simply as uint32 values, not
logically. KnownAssignedXidsAdd() however expects XIDs in logical order,
and calls TransactionIdFollowsOrEquals() to enforce that. If there are
XIDs for which the two orderings disagree, an error is raised and the
recovery fails/restarts.
Hitting this issue is fairly easy - you just need two transactions, one
started before the 4B limit (e.g. XID 4294967290), the other sometime
after it (e.g. XID 1000). Logically (4294967290 <= 1000) but when
compared using xidComparator we try to add them in the opposite order.
Which makes KnownAssignedXidsAdd() fail with an error like this:
ERROR: out-of-order XID insertion in KnownAssignedXids
This only happens during replica startup, while processing RUNNING_XACTS
records to build the snapshot. Once we reach STANDBY_SNAPSHOT_READY, we
skip these records. So this does not affect already running replicas,
but if you restart (or create) a replica while there are transactions
with XIDs for which the two orderings disagree, you may hit this.
Long-running transactions and frequent replica restarts increase the
likelihood of hitting this issue. Once the replica gets into this state,
it can't be started (even if the old transactions are terminated).
Fixed by sorting the XIDs logically - this is fine because we're dealing
with normal XIDs (because it's XIDs assigned to backends) and from the
same wraparound epoch (otherwise the backends could not be running at
the same time on the primary node). So there are no problems with the
triangle inequality, which is why xidComparator compares raw values.
Investigation and root cause analysis by Abhijit Menon-Sen. Patch by me.
This issue is present in all releases since 9.4, however releases up to
9.6 are EOL already so backpatch to 10 only.
Reviewed-by: Abhijit Menon-Sen
Reviewed-by: Alvaro Herrera
Backpatch-through: 10
Discussion: https://postgr.es/m/36b8a501-5d73-277c-4972-f58a4dce088a%40enterprisedb.com
This changes the data type of the catalog fields datcollate, datctype,
collcollate, and collctype from name to text. There wasn't ever a
really good reason for them to be of type name; presumably this was
just carried over from when they were fixed-size fields in pg_control,
first into the corresponding pg_database fields, and then to
pg_collation. The values are not identifiers or object names, and we
don't ever look them up that way.
Changing to type text saves space in the typical case, since locale
names are typically only a few bytes long. But it is also possible
that an ICU locale name with several customization options appended
could be longer than 63 bytes, so this also enables that case, which
was previously probably broken.
Reviewed-by: Julien Rouhaud <rjuju123@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/5e756dd6-0e91-d778-96fd-b1bcb06c161a@2ndquadrant.com
This fixes a set of issues that have accumulated over the past months
(or years) in various code areas. Most fixes are related to some recent
additions, as of the development of v15.
Author: Justin Pryzby
Discussion: https://postgr.es/m/20220124030001.GQ23027@telsasoft.com
pg_basebackup now has a --target=TARGET[:DETAIL] option. If specfied,
it is sent to the server as the value of the TARGET option to the
BASE_BACKUP command. If DETAIL is included, it is sent as the value of
the new TARGET_DETAIL option to the BASE_BACKUP command. If the
target is anything other than 'client', pg_basebackup assumes that it
will now be the server's job to write the backup in a location somehow
defined by the target, and that it therefore needs to write nothing
locally. However, the server will still send messages to the client
for progress reporting purposes.
On the server side, we now support two additional types of backup
targets. There is a 'blackhole' target, which just throws away the
backup data without doing anything at all with it. Naturally, this
should only be used for testing and debugging purposes, since you will
not actually have a backup when it finishes running. More usefully,
there is also a 'server' target, so you can now use something like
'pg_basebackup -Xnone -t server:/SOME/PATH' to write a backup to some
location on the server. We can extend this to more types of targets
in the future, and might even want to create an extensibility
mechanism for adding new target types.
Since WAL fetching is handled with separate client-side logic, it's
not part of this mechanism; thus, backups with non-default targets
must use -Xnone or -Xfetch.
Patch by me, with a bug fix by Jeevan Ladhe. The patch set of which
this is a part has also had review and/or testing from Tushar Ahuja,
Suraj Kharage, Dipesh Pandit, and Mark Dilger.
Discussion: http://postgr.es/m/CA+TgmoaYZbz0=Yk797aOJwkGJC-LK3iXn+wzzMx7KdwNpZhS5g@mail.gmail.com
"jsonlog" is a new value that can be added to log_destination to provide
logs in the JSON format, with its output written to a file, making it
the third type of destination of this kind, after "stderr" and
"csvlog". The format is convenient to feed logs to other applications.
There is also a plugin external to core that provided this feature using
the hook in elog.c, but this had to overwrite the output of "stderr" to
work, so being able to do both at the same time was not possible. The
files generated by this log format are suffixed with ".json", and use
the same rotation policies as the other two formats depending on the
backend configuration.
This takes advantage of the refactoring work done previously in ac7c807,
bed6ed3, 8b76f89 and 2d77d83 for the backend parts, and 72b76f7 for the
TAP tests, making the addition of any new file-based format rather
straight-forward.
The documentation is updated to list all the keys and the values that
can exist in this new format. pg_current_logfile() also required a
refresh for the new option.
Author: Sehrope Sarkuni, Michael Paquier
Reviewed-by: Nathan Bossart, Justin Pryzby
Discussion: https://postgr.es/m/CAH7T-aqswBM6JWe4pDehi1uOiufqe06DJWaU5=X7dDLyqUExHg@mail.gmail.com
This refactors the following routines and facilities coming from
elog.c, to ease their use across multiple log destinations:
- Start timestamp, including its reset, to store when a process has been
started.
- The log timestamp, associated to an entry (the same timestamp is used
when logging across multiple destinations).
- Routine deciding if a query can be logged or not.
- The backend type names, depending on the process that logs any
information (postmaster, bgworker name or just GetBackendTypeDesc() with
a regular backend).
- Write of logs using the logging piped protocol, with the log collector
enabled.
- Error severity converted to a string.
These refactored routines will be used for some follow-up changes
to move all the csvlog logic into its own file and to potentially add
JSON as log destination, reducing the overall size of elog.c as the end
result.
Author: Michael Paquier, Sehrope Sarkuni
Reviewed-by: Nathan Bossart
Discussion: https://postgr.es/m/CAH7T-aqswBM6JWe4pDehi1uOiufqe06DJWaU5=X7dDLyqUExHg@mail.gmail.com
This seems like a clearer name for what it does now.
Provide a compatibility macro so that extensions don't have to convert
to the new name right away.
Discussion: https://postgr.es/m/116024.1640111629@sss.pgh.pa.us
pg_strtouint64() is a wrapper around strtoull/strtoul/_strtoui64, but
it seems no longer necessary to have this indirection.
msvc/Solution.pm claims HAVE_STRTOULL, so the "MSVC only" part seems
unnecessary. Also, we have code in c.h to substitute alternatives for
strtoull() if not found, and that would appear to cover all currently
supported platforms, so having a further fallback in pg_strtouint64()
seems unnecessary.
Therefore, we could remove pg_strtouint64(), and use strtoull()
directly in all call sites. However, it seems useful to keep a
separate notation for parsing exactly 64-bit integers, matching the
type definition int64/uint64. For that, add new macros strtoi64() and
strtou64() in c.h as thin wrappers around strtol()/strtoul() or
strtoll()/stroull(). This makes these functions available everywhere
instead of just in the server code, and it makes the function naming
notably different from the pg_strtointNN() functions in numutils.c,
which have a different API.
Discussion: https://www.postgresql.org/message-id/flat/a3df47c9-b1b4-29f2-7e91-427baf8b75a3%40enterprisedb.com
When determining whether an index update may be skipped by using HOT, we
can ignore attributes indexed only by BRIN indexes. There are no index
pointers to individual tuples in BRIN, and the page range summary will
be updated anyway as it relies on visibility info.
This also removes rd_indexattr list, and replaces it with rd_attrsvalid
flag. The list was not used anywhere, and a simple flag is sufficient.
Patch by Josef Simanek, various fixes and improvements by me.
Author: Josef Simanek
Reviewed-by: Tomas Vondra, Alvaro Herrera
Discussion: https://postgr.es/m/CAFp7QwpMRGcDAQumN7onN9HjrJ3u4X3ZRXdGFT0K5G2JWvnbWg%40mail.gmail.com
Standardize on xoroshiro128** as our basic PRNG algorithm, eliminating
a bunch of platform dependencies as well as fundamentally-obsolete PRNG
code. In addition, this API replacement will ease replacing the
algorithm again in future, should that become necessary.
xoroshiro128** is a few percent slower than the drand48 family,
but it can produce full-width 64-bit random values not only 48-bit,
and it should be much more trustworthy. It's likely to be noticeably
faster than the platform's random(), depending on which platform you
are thinking about; and we can have non-global state vectors easily,
unlike with random(). It is not cryptographically strong, but neither
are the functions it replaces.
Fabien Coelho, reviewed by Dean Rasheed, Aleksander Alekseev, and myself
Discussion: https://postgr.es/m/alpine.DEB.2.22.394.2105241211230.165418@pseudo
Memoize would always use the hash equality operator for the cache key
types to determine if the current set of parameters were the same as some
previously cached set. Certain types such as floating points where -0.0
and +0.0 differ in their binary representation but are classed as equal by
the hash equality operator may cause problems as unless the join uses the
same operator it's possible that whichever join operator is being used
would be able to distinguish the two values. In which case we may
accidentally return in the incorrect rows out of the cache.
To fix this here we add a binary mode to Memoize to allow it to the
current set of parameters to previously cached values by comparing
bit-by-bit rather than logically using the hash equality operator. This
binary mode is always used for LATERAL joins and it's used for normal
joins when any of the join operators are not hashable.
Reported-by: Tom Lane
Author: David Rowley
Discussion: https://postgr.es/m/3004308.1632952496@sss.pgh.pa.us
Backpatch-through: 14, where Memoize was added
A new option "FOR ALL TABLES IN SCHEMA" in Create/Alter Publication allows
one or more schemas to be specified, whose tables are selected by the
publisher for sending the data to the subscriber.
The new syntax allows specifying both the tables and schemas. For example:
CREATE PUBLICATION pub1 FOR TABLE t1,t2,t3, ALL TABLES IN SCHEMA s1,s2;
OR
ALTER PUBLICATION pub1 ADD TABLE t1,t2,t3, ALL TABLES IN SCHEMA s1,s2;
A new system table "pg_publication_namespace" has been added, to maintain
the schemas that the user wants to publish through the publication.
Modified the output plugin (pgoutput) to publish the changes if the
relation is part of schema publication.
Updates pg_dump to identify and dump schema publications. Updates the \d
family of commands to display schema publications and \dRp+ variant will
now display associated schemas if any.
Author: Vignesh C, Hou Zhijie, Amit Kapila
Syntax-Suggested-by: Tom Lane, Alvaro Herrera
Reviewed-by: Greg Nancarrow, Masahiko Sawada, Hou Zhijie, Amit Kapila, Haiying Tang, Ajin Cherian, Rahila Syed, Bharath Rupireddy, Mark Dilger
Tested-by: Haiying Tang
Discussion: https://www.postgresql.org/message-id/CALDaNm0OANxuJ6RXqwZsM1MSY4s19nuH3734j4a72etDwvBETQ@mail.gmail.com
Users sometimes get concerned whe they start the server and it
emits a few messages and then doesn't emit any more messages for
a long time. Generally, what's happening is either that the
system is taking a long time to apply WAL, or it's taking a
long time to reset unlogged relations, or it's taking a long
time to fsync the data directory, but it's not easy to tell
which is the case.
To fix that, add a new 'log_startup_progress_interval' setting,
by default 10s. When an operation that is known to be potentially
long-running takes more than this amount of time, we'll log a
status update each time this interval elapses.
To avoid undesirable log chatter, don't log anything about WAL
replay when in standby mode.
Nitin Jadhav and Robert Haas, reviewed by Amul Sul, Bharath
Rupireddy, Justin Pryzby, Michael Paquier, and Álvaro Herrera.
Discussion: https://postgr.es/m/CA+TgmoaHQrgDFOBwgY16XCoMtXxsrVGFB2jNCvb7-ubuEe1MGg@mail.gmail.com
Discussion: https://postgr.es/m/CAMm1aWaHF7VE69572_OLQ+MgpT5RUiUDgF1x5RrtkJBLdpRj3Q@mail.gmail.com
CIC and REINDEX CONCURRENTLY assume backends see their catalog changes
no later than each backend's next transaction start. That failed to
hold when a backend absorbed a relevant invalidation in the middle of
running RelationBuildDesc() on the CIC index. Queries that use the
resulting index can silently fail to find rows. Fix this for future
index builds by making RelationBuildDesc() loop until it finishes
without accepting a relevant invalidation. It may be necessary to
reindex to recover from past occurrences; REINDEX CONCURRENTLY suffices.
Back-patch to 9.6 (all supported versions).
Noah Misch and Andrey Borodin, reviewed (in earlier versions) by Andres
Freund.
Discussion: https://postgr.es/m/20210730022548.GA1940096@gust.leadboat.com
All the tape functions, like LogicalTapeRead and LogicalTapeWrite, now
take a LogicalTape as argument, instead of LogicalTapeSet+tape number.
You can create any number of LogicalTapes in a single LogicalTapeSet, and
you don't need to decide the number upfront, when you create the tape set.
This makes the tape management in hash agg spilling in nodeAgg.c simpler.
Discussion: https://www.postgresql.org/message-id/420a0ec7-602c-d406-1e75-1ef7ddc58d83%40iki.fi
Reviewed-by: Peter Geoghegan, Zhihong Yu, John Naylor
Commit 84f5c2908 forgot to consider the possibility that
EnsurePortalSnapshotExists could run inside a subtransaction with
lifespan shorter than the Portal's. In that case, the new active
snapshot would be popped at the end of the subtransaction, leaving
a dangling pointer in the Portal, with mayhem ensuing.
To fix, make sure the ActiveSnapshot stack entry is marked with
the same subtransaction nesting level as the associated Portal.
It's certainly safe to do so since we won't be here at all unless
the stack is empty; hence we can't create an out-of-order stack.
Let's also apply this logic in the case where PortalRunUtility
sets portalSnapshot, just to be sure that path can't cause similar
problems. It's slightly less clear that that path can't create
an out-of-order stack, so add an assertion guarding it.
Report and patch by Bertrand Drouvot (with kibitzing by me).
Back-patch to v11, like the previous commit.
Discussion: https://postgr.es/m/ff82b8c5-77f4-3fe7-6028-fcf3303e82dd@amazon.com
That allows to include just visibilitymapdefs.h from file.c, and in turn,
remove include of postgres.h from relcache.h.
Reported-by: Andres Freund
Discussion: https://postgr.es/m/20210913232614.czafiubr435l6egi%40alap3.anarazel.de
Author: Alexander Korotkov
Reviewed-by: Andres Freund, Tom Lane, Alvaro Herrera
Backpatch-through: 13
Until now, the -C option of postgres was handled before a small subset
of GUCs computed at runtime are initialized, leading to incorrect
results as GUC machinery would fall back to default values for such
parameters.
For example, data_checksums could report "off" for a cluster as the
control file is not loaded yet. Or wal_segment_size would show a
segment size at 16MB even if initdb --wal-segsize used something else.
Worse, the command would fail to properly report the recently-introduced
shared_memory, that requires to load shared_preload_libraries as these
could ask for a chunk of shared memory.
Support for runtime GUCs comes with a limitation, as the operation is
now allowed on a running server. One notable reason for this is that
_PG_init() functions of loadable libraries are called before all
runtime-computed GUCs are initialized, and this is not guaranteed to be
safe to do on running servers. For the case of shared_memory_size,
where we want to know how much memory would be used without allocating
it, this limitation is fine. Another case where this will help is for
huge pages, with the introduction of a different GUC to evaluate the
amount of huge pages required for a server before starting it, without
having to allocate large chunks of memory.
This feature is controlled with a new GUC flag, and four parameters are
classified as runtime-computed as of this change:
- data_checksums
- shared_memory_size
- data_directory_mode
- wal_segment_size
Some TAP tests are added to provide some coverage here, using
data_checksums in the tests of pg_checksums.
Per discussion with Andres Freund, Justin Pryzby, Magnus Hagander and
more.
Author: Nathan Bossart
Discussion: https://postgr.es/m/F2772387-CE0F-46BF-B5F1-CC55516EB885@amazon.com
This is a combined revert of the following commits:
- c3826f8, a refactoring piece that moved the hex decoding code to
src/common/. This code was cleaned up by aef8948, as it originally
included no overflow checks in the same way as the base64 routines in
src/common/ used by SCRAM, making it unsafe for its purpose.
- aef8948, a more advanced refactoring of the hex encoding/decoding code
to src/common/ that added sanity checks on the result buffer for hex
decoding and encoding. As reported by Hans Buschmann, those overflow
checks are expensive, and it is possible to see a performance drop in
the decoding/encoding of bytea or LOs the longer they are. Simple SQLs
working on large bytea values show a clear difference in perf profile.
- ccf4e27, a cleanup made possible by aef8948.
The reverts of all those commits bring back the performance of hex
decoding and encoding back to what it was in ~13. Fow now and
post-beta3, this is the simplest option.
Reported-by: Hans Buschmann
Discussion: https://postgr.es/m/1629039545467.80333@nidsa.net
Backpatch-through: 14
If the replacement string doesn't contain \1...\9, then we don't
need sub-match locations, so we can use the REG_NOSUB optimization
here too. There's already a pre-scan of the replacement string
to look for backslashes, so extend that to check for digits, and
refactor to allow that to happen before we compile the regexp.
While at it, try to speed up the pre-scan by using memchr() instead
of a handwritten loop. It's likely that this is lost in the noise
compared to the regexp processing proper, but maybe not. In any
case, this coding is shorter.
Also, add some test cases to improve the poor coverage of
appendStringInfoRegexpSubstr().
Discussion: https://postgr.es/m/3534632.1628536485@sss.pgh.pa.us
This patch adds new functions regexp_count(), regexp_instr(),
regexp_like(), and regexp_substr(), and extends regexp_replace()
with some new optional arguments. All these functions follow
the definitions used in Oracle, although there are small differences
in the regexp language due to using our own regexp engine -- most
notably, that the default newline-matching behavior is different.
Similar functions appear in DB2 and elsewhere, too. Aside from
easing portability, these functions are easier to use for certain
tasks than our existing regexp_match[es] functions.
Gilles Darold, heavily revised by me
Discussion: https://postgr.es/m/fc160ee0-c843-b024-29bb-97b5da61971f@darold.net
Formerly, when specifying NUMERIC(precision, scale), the scale had to
be in the range [0, precision], which was per SQL spec. This commit
extends the range of allowed scales to [-1000, 1000], independent of
the precision (whose valid range remains [1, 1000]).
A negative scale implies rounding before the decimal point. For
example, a column might be declared with a scale of -3 to round values
to the nearest thousand. Note that the display scale remains
non-negative, so in this case the display scale will be zero, and all
digits before the decimal point will be displayed.
A scale greater than the precision supports fractional values with
zeros immediately after the decimal point.
Take the opportunity to tidy up the code that packs, unpacks and
validates the contents of a typmod integer, encapsulating it in a
small set of new inline functions.
Bump the catversion because the allowed contents of atttypmod have
changed for numeric columns. This isn't a change that requires a
re-initdb, but negative scale values in the typmod would confuse old
backends.
Dean Rasheed, with additional improvements by Tom Lane. Reviewed by
Tom Lane.
Discussion: https://postgr.es/m/CAEZATCWdNLgpKihmURF8nfofP0RFtAKJ7ktY6GcZOPnMfUoRqA@mail.gmail.com
The idea behind this patch is to design out bugs like the one fixed
by commit 9d523119f. Previously, once one did RelationOpenSmgr(rel),
it was considered okay to access rel->rd_smgr directly for some
not-very-clear interval. But since that pointer will be cleared by
relcache flushes, we had bugs arising from overreliance on a previous
RelationOpenSmgr call still being effective.
Now, very little code except that in rel.h and relcache.c should ever
touch the rd_smgr field directly. The normal coding rule is to use
RelationGetSmgr(rel) and not expect the result to be valid for longer
than one smgr function call. There are a couple of places where using
the function every single time seemed like overkill, but they are now
annotated with large warning comments.
Amul Sul, after an idea of mine.
Discussion: https://postgr.es/m/CANiYTQsU7yMFpQYnv=BrcRVqK_3U3mtAzAsJCaqtzsDHfsUbdQ@mail.gmail.com
This has the advantage to make a process more responsive when the
postmaster dies, even if the wait time was rather limited as there was
only a 50ms timeout here. Another advantage of this change is for
monitoring, as we gain a new wait event for the end-of-vacuum
truncation.
Author: Bharath Rupireddy
Reviewed-by: Aleksander Alekseev, Thomas Munro, Michael Paquier
Discussion: https://postgr.es/m/CALj2ACU4AdPCq6NLfcA-ZGwX7pPCK5FgEj-CAU0xCKzkASSy_A@mail.gmail.com
Generalize the INDEX_CLEANUP VACUUM parameter (and the corresponding
reloption): make it into a ternary style boolean parameter. It now
exposes a third option, "auto". The "auto" option (which is now the
default) enables the "bypass index vacuuming" optimization added by
commit 1e55e7d1.
"VACUUM (INDEX_CLEANUP TRUE)" is redefined to once again make VACUUM
simply do any required index vacuuming, regardless of how few dead
tuples are encountered during the first scan of the target heap relation
(unless there are exactly zero). This gives users a way of opting out
of the "bypass index vacuuming" optimization, if for whatever reason
that proves necessary. It is also expected to be used by PostgreSQL
developers as a testing option from time to time.
"VACUUM (INDEX_CLEANUP FALSE)" does the same thing as it always has: it
forcibly disables both index vacuuming and index cleanup. It's not
expected to be used much in PostgreSQL 14. The failsafe mechanism added
by commit 1e55e7d1 addresses the same problem in a simpler way.
INDEX_CLEANUP can now be thought of as a testing and compatibility
option.
Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Masahiko Sawada <sawada.mshk@gmail.com>
Reviewed-By: Justin Pryzby <pryzby@telsasoft.com>
Discussion: https://postgr.es/m/CAH2-WznrBoCST4_Gxh_G9hA8NzGUbeBGnOUC8FcXcrhqsv6OHQ@mail.gmail.com
COMMIT/ROLLBACK necessarily destroys all snapshots within the session.
The original implementation of intra-procedure transactions just
cavalierly did that, ignoring the fact that this left us executing in
a rather different environment than normal. In particular, it turns
out that handling of toasted datums depends rather critically on there
being an outer ActiveSnapshot: otherwise, when SPI or the core
executor pop whatever snapshot they used and return, it's unsafe to
dereference any toasted datums that may appear in the query result.
It's possible to demonstrate "no known snapshots" and "missing chunk
number N for toast value" errors as a result of this oversight.
Historically this outer snapshot has been held by the Portal code,
and that seems like a good plan to preserve. So add infrastructure
to pquery.c to allow re-establishing the Portal-owned snapshot if it's
not there anymore, and add enough bookkeeping support that we can tell
whether it is or not.
We can't, however, just re-establish the Portal snapshot as part of
COMMIT/ROLLBACK. As in normal transaction start, acquiring the first
snapshot should wait until after SET and LOCK commands. Hence, teach
spi.c about doing this at the right time. (Note that this patch
doesn't fix the problem for any PLs that try to run intra-procedure
transactions without using SPI to execute SQL commands.)
This makes SPI's no_snapshots parameter rather a misnomer, so in HEAD,
rename that to allow_nonatomic.
replication/logical/worker.c also needs some fixes, because it wasn't
careful to hold a snapshot open around AFTER trigger execution.
That code doesn't use a Portal, which I suspect someday we're gonna
have to fix. But for now, just rearrange the order of operations.
This includes back-patching the recent addition of finish_estate()
to centralize the cleanup logic there.
This also back-patches commit 2ecfeda3e into v13, to improve the
test coverage for worker.c (it was that test that exposed that
worker.c's snapshot management is wrong).
Per bug #15990 from Andreas Wicht. Back-patch to v11 where
intra-procedure COMMIT was added.
Discussion: https://postgr.es/m/15990-eee2ac466b11293d@postgresql.org
Allowing only on/off meant that all either all existing configuration
guides would become obsolete if we disabled it by default, or that we
would have to accept a performance loss in the default config if we
enabled it by default. By allowing 'auto' as a middle ground, the
performance cost is only paid by those who enable pg_stat_statements and
similar modules.
I only edited the release notes to comment-out a paragraph that is now
factually wrong; further edits are probably needed to describe the
related change in more detail.
Author: Julien Rouhaud <rjuju123@gmail.com>
Reviewed-by: Justin Pryzby <pryzby@telsasoft.com>
Discussion: https://postgr.es/m/20210513002623.eugftm4nk2lvvks3@nol
Also "make reformat-dat-files".
The only change worthy of note is that pgindent messed up the formatting
of launcher.c's struct LogicalRepWorkerId, which led me to notice that
that struct wasn't used at all anymore, so I just took it out.
While we were (mostly) careful about ensuring that the dimensions of
arrays aren't large enough to cause integer overflow, the lower bound
values were generally not checked. This allows situations where
lower_bound + dimension overflows an integer. It seems that that's
harmless so far as array reading is concerned, except that array
elements with subscripts notionally exceeding INT_MAX are inaccessible.
However, it confuses various array-assignment logic, resulting in a
potential for memory stomps.
Fix by adding checks that array lower bounds aren't large enough to
cause lower_bound + dimension to overflow. (Note: this results in
disallowing cases where the last subscript position would be exactly
INT_MAX. In principle we could probably allow that, but there's a lot
of code that computes lower_bound + dimension and would need adjustment.
It seems doubtful that it's worth the trouble/risk to allow it.)
Somewhat independently of that, array_set_element() was careless
about possible overflow when checking the subscript of a fixed-length
array, creating a different route to memory stomps. Fix that too.
Security: CVE-2021-32027
This set of commits has some bugs with known fixes, but at this late
stage in the release cycle it seems best to revert and resubmit next
time, along with some new automated test coverage for this whole area.
Commits reverted:
dc88460c: Doc: Review for "Optionally prefetch referenced data in recovery."
1d257577: Optionally prefetch referenced data in recovery.
f003d9f8: Add circular WAL decoding buffer.
323cbe7c: Remove read_page callback from XLogReader.
Remove the new GUC group WAL_RECOVERY recently added by a55a9847, as the
corresponding section of config.sgml is now reverted.
Discussion: https://postgr.es/m/CAOuzzgrn7iKnFRsB4MHp3UisEQAGgZMbk_ViTN4HV4-Ksq8zCg%40mail.gmail.com
It seems that various people have moved GUCs around in the config.sgml
listing without bothering to make the code agree. Ensure that the
config_group codes assigned to GUCs match where they are listed in
config.sgml. Likewise ensure that postgresql.conf.sample lists GUCs
in the same sub-section and same ordering as they appear in config.sgml.
(I've got some doubts about some of these choices, but for the purposes
of this patch, we'll treat config.sgml as gospel.)
Notably, this requires adding a WAL_RECOVERY config_group value,
because 1d257577e didn't. As long as we're renumbering that enum
anyway, let's take out the values corresponding to major groups
that are divided into sub-groups. No GUC should be assigned to the
major group itself, so those values just create a temptation to
do the wrong thing, while adding work for translators.
In passing, adjust the short_desc strings for PRESET_OPTIONS GUCs
to uniformly use the phrasing "Shows XYZ.", removing the impression
some of these strings left that you can set the value.
While some of these errors are old, no back-patch, as changing the
contents of the pg_settings view in stable branches seems more likely
to be seen as a compatibility break than anything helpful.
Bharath Rupireddy, Justin Pryzby, Tom Lane
Discussion: https://postgr.es/m/16997-ff16127f6e0d1390@postgresql.org
Discussion: https://postgr.es/m/20210413123139.GE6091@telsasoft.com
Design problems were discovered in the handling of composite types and
record types that would cause some relevant versions not to be recorded.
Misgivings were also expressed about the use of the pg_depend catalog
for this purpose. We're out of time for this release so we'll revert
and try again.
Commits reverted:
1bf946bd: Doc: Document known problem with Windows collation versions.
cf002008: Remove no-longer-relevant test case.
ef387bed: Fix bogus collation-version-recording logic.
0fb0a050: Hide internal error for pg_collation_actual_version(<bad OID>).
ff942057: Suppress "warning: variable 'collcollate' set but not used".
d50e3b1f: Fix assertion in collation version lookup.
f24b1569: Rethink extraction of collation dependencies.
257836a7: Track collation versions for indexes.
cd6f479e: Add pg_depend.refobjversion.
7d1297df: Remove pg_collation.collversion.
Discussion: https://postgr.es/m/CA%2BhUKGLhj5t1fcjqAu8iD9B3ixJtsTNqyCCD4V0aTO9kAKAjjA%40mail.gmail.com
In d6b8d29419 I (Álvaro) was sloppy about recording whether a
partition descripor does or does not include detached partitions, when
the snapshot checking does not see the pg_inherits row marked detached.
In that case no partition was omitted, yet in the relcache entry we were
saving the partdesc as omitting partitions. Flip that (so we save it as
a partdesc not omitting partitions, which indeed it doesn't), which
hopefully makes the code easier to reason about.
Author: Amit Langote <amitlangote09@gmail.com>
Discussion: https://postgr.es/m/CA+HiwqE7GxGU4VdzwZzfiz+Ont5SsopoFkgtrZGEdPqWRL+biA@mail.gmail.com
Makes partition descriptor acquisition faster during the transient
period in which a partition is in the process of being detached.
This also adds the restriction that only one partition can be in
pending-detach state for a partitioned table.
While at it, return find_inheritance_children() API to what it was
before 71f4c8c6f7, and create a separate
find_inheritance_children_extended() that returns detailed info about
detached partitions.
(This incidentally fixes a bug in 8aba932251 whereby a memory context
holding a transient partdesc is reparented to a NULL PortalContext,
leading to permanent leak of that memory. The fix is to no longer rely
on reparenting contexts to PortalContext. Reported by Amit Langote.)
Per gripe from Amit Langote
Discussion: https://postgr.es/m/CA+HiwqFgpP1LxJZOBYGt9rpvTjXXkg5qG2+Xch2Z1Q7KrqZR1A@mail.gmail.com
The Truncate operation acquires an exclusive lock on the target relation
and indexes. It then waits for logical replication of the operation to
finish at commit. Now because we are acquiring the shared lock on the
target index to get index attributes in pgoutput while sending the
changes for the Truncate operation, it leads to a deadlock.
Actually, we don't need to acquire a lock on the target index as we build
the cache entry using a historic snapshot and all the later changes are
absorbed while decoding WAL. So, we wrote a special purpose function for
logical replication to get a bitmap of replica identity attribute numbers
where we get that information without locking the target index.
We decided not to backpatch this as there doesn't seem to be any field
complaint about this issue since it was introduced in commit 5dfd1e5a in
v11.
Reported-by: Haiying Tang
Author: Takamichi Osumi, test case by Li Japin
Reviewed-by: Amit Kapila, Ajin Cherian
Discussion: https://postgr.es/m/OS0PR01MB6113C2499C7DC70EE55ADB82FB759@OS0PR01MB6113.jpnprd01.prod.outlook.com
Previously, it was pg_stat_activity.queryid to match the
pg_stat_statements queryid column. This is an adjustment to patch
4f0b0966c8. This also adjusts some of the internal function calls to
match. Catversion bumped.
Reported-by: Álvaro Herrera, Julien Rouhaud
Discussion: https://postgr.es/m/20210408032704.GA7498@alvherre.pgsql
We'd previously noted the need for coping with Windows headers
that provide some other definition of macro "ERROR" than elog.h
does. It turns out that R also wants to define ERROR, and
WARNING too. PL/R has been working around this in a hacky way
that broke when we recently changed the numeric value of ERROR.
To let them have a more future-proof solution, provide an
alternate macro PGWARNING for WARNING, and make PGERROR visible
always, not only when #ifdef WIN32.
Discussion: https://postgr.es/m/CADK3HHK6iMChd1yoOqssxBn5Z14Zar8Ztr3G-N_fuG7F8YTP3w@mail.gmail.com
Comment fixes are applied on HEAD, and documentation improvements are
applied on back-branches where needed.
Author: Justin Pryzby
Discussion: https://postgr.es/m/20210408164008.GJ6592@telsasoft.com
Backpatch-through: 9.6
This commit introduces new foreign data wrapper API for TRUNCATE.
It extends TRUNCATE command so that it accepts foreign tables as
the targets to truncate and invokes that API. Also it extends postgres_fdw
so that it can issue TRUNCATE command to foreign servers, by adding
new routine for that TRUNCATE API.
The information about options specified in TRUNCATE command, e.g.,
ONLY, CACADE, etc is passed to FDW via API. The list of foreign tables to
truncate is also passed to FDW. FDW truncates the foreign data sources
that the passed foreign tables specify, based on those information.
For example, postgres_fdw constructs TRUNCATE command using them
and issues it to the foreign server.
For performance, TRUNCATE command invokes the FDW routine for
TRUNCATE once per foreign server that foreign tables to truncate belong to.
Author: Kazutaka Onishi, Kohei KaiGai, slightly modified by Fujii Masao
Reviewed-by: Bharath Rupireddy, Michael Paquier, Zhihong Yu, Alvaro Herrera, Stephen Frost, Ashutosh Bapat, Amit Langote, Daniel Gustafsson, Ibrar Ahmed, Fujii Masao
Discussion: https://postgr.es/m/CAOP8fzb_gkReLput7OvOK+8NHgw-RKqNv59vem7=524krQTcWA@mail.gmail.com
Discussion: https://postgr.es/m/CAJuF6cMWDDqU-vn_knZgma+2GMaout68YUgn1uyDnexRhqqM5Q@mail.gmail.com
Introduce a new GUC recovery_prefetch, disabled by default. When
enabled, look ahead in the WAL and try to initiate asynchronous reading
of referenced data blocks that are not yet cached in our buffer pool.
For now, this is done with posix_fadvise(), which has several caveats.
Better mechanisms will follow in later work on the I/O subsystem.
The GUC maintenance_io_concurrency is used to limit the number of
concurrent I/Os we allow ourselves to initiate, based on pessimistic
heuristics used to infer that I/Os have begun and completed.
The GUC wal_decode_buffer_size is used to limit the maximum distance we
are prepared to read ahead in the WAL to find uncached blocks.
Reviewed-by: Alvaro Herrera <alvherre@2ndquadrant.com> (parts)
Reviewed-by: Andres Freund <andres@anarazel.de> (parts)
Reviewed-by: Tomas Vondra <tomas.vondra@2ndquadrant.com> (parts)
Tested-by: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Tested-by: Jakub Wartak <Jakub.Wartak@tomtom.com>
Tested-by: Dmitry Dolgov <9erthalion6@gmail.com>
Tested-by: Sait Talha Nisanci <Sait.Nisanci@microsoft.com>
Discussion: https://postgr.es/m/CA%2BhUKGJ4VJN8ttxScUFM8dOKX0BrBiboo5uz1cq%3DAovOddfHpA%40mail.gmail.com
This adds a function, pg_wait_for_backend_termination(), and a new
timeout argument to pg_terminate_backend(), which will wait for the
backend to actually terminate (with or without signaling it to do so
depending on which function is called). The default behaviour of
pg_terminate_backend() remains being timeout=0 which does not waiting.
For pg_wait_for_backend_termination() the default wait is 5 seconds.
Author: Bharath Rupireddy
Reviewed-By: Fujii Masao, David Johnston, Muhammad Usama,
Hou Zhijie, Magnus Hagander
Discussion: https://postgr.es/m/CALj2ACUBpunmyhYZw-kXCYs5NM+h6oG_7Df_Tn4mLmmUQifkqA@mail.gmail.com
Use the in-core query id computation for pg_stat_activity,
log_line_prefix, and EXPLAIN VERBOSE.
Similar to other fields in pg_stat_activity, only the queryid from the
top level statements are exposed, and if the backends status isn't
active then the queryid from the last executed statements is displayed.
Add a %Q placeholder to include the queryid in log_line_prefix, which
will also only expose top level statements.
For EXPLAIN VERBOSE, if a query identifier has been computed, either by
enabling compute_query_id or using a third-party module, display it.
Bump catalog version.
Discussion: https://postgr.es/m/20210407125726.tkvjdbw76hxnpwfi@nol
Author: Julien Rouhaud
Reviewed-by: Alvaro Herrera, Nitin Jadhav, Zhihong Yu
Add compute_query_id GUC to control whether a query identifier should be
computed by the core (off by default). It's thefore now possible to
disable core queryid computation and use pg_stat_statements with a
different algorithm to compute the query identifier by using a
third-party module.
To ensure that a single source of query identifier can be used and is
well defined, modules that calculate a query identifier should throw an
error if compute_query_id specified to compute a query id and if a query
idenfitier was already calculated.
Discussion: https://postgr.es/m/20210407125726.tkvjdbw76hxnpwfi@nol
Author: Julien Rouhaud
Reviewed-by: Alvaro Herrera, Nitin Jadhav, Zhihong Yu
The previous implementation of EXTRACT mapped internally to
date_part(), which returned type double precision (since it was
implemented long before the numeric type existed). This can lead to
imprecise output in some cases, so returning numeric would be
preferrable. Changing the return type of an existing function is a
bit risky, so instead we do the following: We implement a new set of
functions, which are now called "extract", in parallel to the existing
date_part functions. They work the same way internally but use
numeric instead of float8. The EXTRACT construct is now mapped by the
parser to these new extract functions. That way, dumps of views
etc. from old versions (which would use date_part) continue to work
unchanged, but new uses will map to the new extract functions.
Additionally, the reverse compilation of EXTRACT now reproduces the
original syntax, using the new mechanism introduced in
40c24bfef9.
The following minor changes of behavior result from the new
implementation:
- The column name from an isolated EXTRACT call is now "extract"
instead of "date_part".
- Extract from date now rejects inappropriate field names such as
HOUR. It was previously mapped internally to extract from
timestamp, so it would silently accept everything appropriate for
timestamp.
- Return values when extracting fields with possibly fractional
values, such as second and epoch, now have the full scale that the
value has internally (so, for example, '1.000000' instead of just
'1').
Reported-by: Petr Fedorov <petr.fedorov@phystech.edu>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/flat/42b73d2d-da12-ba9f-570a-420e0cce19d9@phystech.edu
