This commit introduces pg_stat_recovery, that exposes at SQL level the
state of recovery as tracked by XLogRecoveryCtlData in shared memory,
maintained by the startup process. This new view includes the following
fields, that are useful for monitoring purposes on a standby, once it
has reached a consistent state (making the execution of the SQL function
possible):
- Last-successfully replayed WAL record LSN boundaries and its timeline.
- Currently replaying WAL record end LSN and its timeline.
- Current WAL chunk start time.
- Promotion trigger state.
- Timestamp of latest processed commit/abort.
- Recovery pause state.
Some of this data can already be recovered from different system
functions, but not all of it. See pg_get_wal_replay_pause_state or
pg_last_xact_replay_timestamp. This new view offers a stronger
consistency guarantee, by grabbing the recovery state for all fields
through one spinlock acquisition.
The system view relies on a new function, called pg_stat_get_recovery().
Querying this data requires the pg_read_all_stats privilege. The view
returns no rows if the node is not in recovery.
This feature originates from a suggestion I have made while discussion
the addition of a CONNECTING state to the WAL receiver's shared memory
state, because we lacked access to some of the state data. The author
has taken the time to implement it, so thanks for that.
Bump catalog version.
Author: Xuneng Zhou <xunengzhou@gmail.com>
Discussion: https://postgr.es/m/CABPTF7W+Nody-+P9y4PNk37-QWuLpfUrEonHuEhrX+Vx9Kq+Kw@mail.gmail.com
Discussion: https://postgr.es/m/aW13GJn_RfTJIFCa@paquier.xyz
This adds a function for retrieving memory context statistics
and information from backends as well as auxiliary processes.
The intended usecase is cluster debugging when under memory
pressure or unanticipated memory usage characteristics.
When calling the function it sends a signal to the specified
process to submit statistics regarding its memory contexts
into dynamic shared memory. Each memory context is returned
in detail, followed by a cumulative total in case the number
of contexts exceed the max allocated amount of shared memory.
Each process is limited to use at most 1Mb memory for this.
A summary can also be explicitly requested by the user, this
will return the TopMemoryContext and a cumulative total of
all lower contexts.
In order to not block on busy processes the caller specifies
the number of seconds during which to retry before timing out.
In the case where no statistics are published within the set
timeout, the last known statistics are returned, or NULL if
no previously published statistics exist. This allows dash-
board type queries to continually publish even if the target
process is temporarily congested. Context records contain a
timestamp to indicate when they were submitted.
Author: Rahila Syed <rahilasyed90@gmail.com>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Tomas Vondra <tomas@vondra.me>
Reviewed-by: Atsushi Torikoshi <torikoshia@oss.nttdata.com>
Reviewed-by: Fujii Masao <masao.fujii@oss.nttdata.com>
Reviewed-by: Alexander Korotkov <aekorotkov@gmail.com>
Discussion: https://postgr.es/m/CAH2L28v8mc9HDt8QoSJ8TRmKau_8FM_HKS41NeO9-6ZAkuZKXw@mail.gmail.com
If a time zone abbreviation used in datetime input is defined in
the currently active timezone, use that definition in preference
to looking in the timezone_abbreviations list. That allows us to
correctly handle abbreviations that have different meanings in
different timezones. Also, it eliminates an inconsistency between
datetime input and datetime output: the non-ISO datestyles for
timestamptz have always printed abbreviations taken from the IANA
data, not from timezone_abbreviations. Before this fix, it was
possible to demonstrate cases where casting a timestamp to text
and back fails or changes the value significantly because of that
inconsistency.
While this change removes the ability to override the IANA data about
an abbreviation known in the current zone, it's not clear that there's
any real use-case for doing so. But it is clear that this makes life
a lot easier for dealing with abbreviations that have conflicts across
different time zones.
Also update the pg_timezone_abbrevs view to report abbreviations
that are recognized via the IANA data, and *not* report any
timezone_abbreviations entries that are thereby overridden.
Under the hood, there are now two SRFs, one that pulls the IANA
data and one that pulls timezone_abbreviations entries. They're
combined by logic in the view. This approach was useful for
debugging (since the functions can be called on their own).
While I don't intend to document the functions explicitly,
they might be useful to call directly.
Also improve DecodeTimezoneAbbrev's caching logic so that it can
cache zone abbreviations found in the IANA data. Without that,
this patch would have caused a noticeable degradation of the
runtime of timestamptz_in.
Per report from Aleksander Alekseev and additional investigation.
Discussion: https://postgr.es/m/CAJ7c6TOATjJqvhnYsui0=CO5XFMF4dvTGH+skzB--jNhqSQu5g@mail.gmail.com
32d3ed816 added the "path" column to pg_backend_memory_contexts to allow
a stable method of obtaining the parent MemoryContext of a given row in
the view. Using the "path" column is now the preferred method of
obtaining the parent row.
Previously, any queries which were self-joining to this view using the
"name" and "parent" columns could get incorrect results due to the fact
that names are not unique. Here we aim to explicitly break such queries
so that they can be corrected and use the "path" column instead.
It is possible that there are more innocent users of the parent column
that just need an indication of the parent and having to write out a
self-joining CTE may be an unnecessary hassle for those cases. Let's
remove the column for now and see if anyone comes back with any
complaints. This does seem like a good time to attempt to get rid of
the column as we still have around 1 year to revert this if someone comes
back with a valid complaint. Plus this view is new to v14 and is quite
niche, so perhaps not many people will be affected.
Author: Melih Mutlu <m.melihmutlu@gmail.com>
Discussion: https://postgr.es/m/CAGPVpCT7NOe4fZXRL8XaoxHpSXYTu6GTpULT_3E-HT9hzjoFRA@mail.gmail.com
"path" provides a reliable method of determining the parent/child
relationships between memory contexts. Previously this could be done in
a non-reliable way by writing a recursive query and joining the "parent"
and "name" columns. This wasn't reliable as the names were not unique,
which could result in joining to the wrong parent.
To make this reliable, "path" stores an array of numerical identifiers
starting with the identifier for TopLevelMemoryContext. It contains an
element for each intermediate parent between that and the current context.
Incompatibility: Here we also adjust the "level" column to make it
1-based rather than 0-based. A 1-based level provides a convenient way
to access elements in the "path" array. e.g. path[level] gives the
identifier for the current context.
Identifiers are not stable across multiple evaluations of the view. In
an attempt to make these more stable for ad-hoc queries, the identifiers
are assigned breadth-first. Contexts closer to TopLevelMemoryContext
are less likely to change between queries and during queries.
Author: Melih Mutlu <m.melihmutlu@gmail.com>
Discussion: https://postgr.es/m/CAGPVpCThLyOsj3e_gYEvLoHkr5w=tadDiN_=z2OwsK3VJppeBA@mail.gmail.com
Reviewed-by: Andres Freund, Stephen Frost, Atsushi Torikoshi,
Reviewed-by: Michael Paquier, Robert Haas, David Rowley
There were no callers of BumpAllocLarge() in the regression tests, so
here we add a sort with a tuple large enough to use that path in bump.c.
Also, BumpStats() wasn't being called, so add a test to sysviews.sql to
call pg_backend_memory_contexts() while a bump context exists in the
backend.
Reported-by: Andres Freund
Discussion: https://postgr.es/m/20240414223305.m3i5eju6zylabvln@awork3.anarazel.de
This new view, wrapped around a SRF, shows some information known about
wait events, as of:
- Name.
- Type (Activity, I/O, Extension, etc.).
- Description.
All the information retrieved comes from wait_event_names.txt, and the
description is the same as the documentation with filters applied to
remove any XML markups. This view is useful when joined with
pg_stat_activity to get the description of a wait event reported.
Custom wait events for extensions are included in the view.
Original idea by Yves Colin.
Author: Bertrand Drouvot
Reviewed-by: Kyotaro Horiguchi, Masahiro Ikeda, Tom Lane, Michael
Paquier
Discussion: https://postgr.es/m/0e2ae164-dc89-03c3-cf7f-de86378053ac@gmail.com
This view is similar to pg_hba_file_rules view, except that it is
associated with the parsing of pg_ident.conf. Similarly to its cousin,
this view is useful to check via SQL if changes planned in pg_ident.conf
would work upon reload or restart, or to diagnose a previous failure.
Bumps catalog version.
Author: Julien Rouhaud
Reviewed-by: Aleksander Alekseev, Michael Paquier
Discussion: https://postgr.es/m/20220223045959.35ipdsvbxcstrhya@jrouhaud
The regression tests include a query to check the execution path of
pg_hba_file_rules, but it has never checked that a given cluster has
correct contents in pg_hba.conf. This commit extends the query of
pg_hba_file_rules to report any errors if anything bad is found. For
EXEC_BACKEND builds, any connection attempt would fail when loading
pg_hba.conf if any incorrect content is found when parsed, so a failure
would be detected before even running this query. However, this can
become handy for clusters where pg_hba.conf can be reloaded, where new
connection attempts are not subject to a fresh loading of pg_hba.conf.
Author: Julien Rouhaud, based on an idea from me
Discussion: https://postgr.es/m/YkFhpydhyeNNo3Xl@paquier.xyz
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_stat_get_slru() in pgstatfuncs.c would point to one element after the
end of the array PgStat_SLRUStats when finishing to scan its entries.
This had no direct consequences as no data from the extra memory area
was read, but static analyzers would rightfully complain here. So let's
be clean.
While on it, this adds one regression test in the area reserved for
system views.
Reported-by: Alexander Kozhemyakin, via AddressSanitizer
Author: Kyotaro Horiguchi
Discussion: https://postgr.es/m/17280-37da556e86032070@postgresql.org
Backpatch-through: 13
Commit 2c8dd05d6c added the atomic variable writtenUpto into
walreceiver's shared memory information. It's initialized only
when walreceiver started up but could be read via pg_stat_wal_receiver
view anytime, i.e., even before it's initialized. In the server built
with --disable-atomics and --disable-spinlocks, this uninitialized
atomic variable read could cause "invalid spinlock number: 0" error.
This commit changed writtenUpto so that it's initialized at
the postmaster startup, to avoid the uninitialized variable read
via pg_stat_wal_receiver and fix the error.
Also this commit moved the read of writtenUpto after the release
of spinlock protecting walreceiver's shared variables. This is
necessary to prevent new spinlock from being taken by atomic
variable read while holding another spinlock, and to shorten
the spinlock duration. This change leads writtenUpto not to be
consistent with the other walreceiver's shared variables protected
by a spinlock. But this is OK because writtenUpto should not be
used for data integrity checks.
Back-patch to v13 where commit 2c8dd05d6c introduced the bug.
Author: Fujii Masao
Reviewed-by: Michael Paquier, Thomas Munro, Andres Freund
Discussion: https://postgr.es/m/7ef8708c-5b6b-edd3-2cf2-7783f1c7c175@oss.nttdata.com
This view shows the statistics about WAL activity. Currently it has only
two columns: wal_buffers_full and stats_reset. wal_buffers_full column
indicates the number of times WAL data was written to the disk because
WAL buffers got full. This information is useful when tuning wal_buffers.
stats_reset column indicates the time at which these statistics were
last reset.
pg_stat_wal view is also the basic infrastructure to expose other
various statistics about WAL activity later.
Bump PGSTAT_FILE_FORMAT_ID due to the change in pgstat format.
Bump catalog version.
Author: Masahiro Ikeda
Reviewed-by: Takayuki Tsunakawa, Kyotaro Horiguchi, Amit Kapila, Fujii Masao
Discussion: https://postgr.es/m/188bd3f2d2233cf97753b5ced02bb050@oss.nttdata.com
This view is designed along the same lines as pg_file_settings, to wit
it shows what is currently in the file, not what the postmaster has
loaded as the active settings. That allows it to be used to pre-vet
edits before issuing SIGHUP. As with the earlier view, go out of our
way to allow errors in the file to be reflected in the view, to assist
that use-case.
(We might at some point invent a view to show the current active settings,
but this is not that patch; and it's not trivial to do.)
Haribabu Kommi, reviewed by Ashutosh Bapat, Michael Paquier, Simon Riggs,
and myself
Discussion: https://postgr.es/m/CAJrrPGerH4jiwpcXT1-46QXUDmNp2QDrG9+-Tek_xC8APHShYw@mail.gmail.com
Quite a few of our built-in system views were not exercised anywhere
in the regression tests. This is perhaps not so exciting for the ones
that are simple projections/joins of system catalogs, but for the ones
that are wrappers for set-returning C functions, the omission translates
directly to lack of test coverage for those functions.
In many cases, the reason for the omission is that the view doesn't have
much to do with any specific SQL feature, so there's no natural place to
test it. To remedy that, invent a new script sysviews.sql that's dedicated
to testing SRF-based views. Move a couple of tests that did fit this
charter into the new script, and add simple "count(*)" based tests of
other views within the charter. That's enough to ensure we at least
exercise the main code path through the SRF, although it does little to
prove that the output is sane.
More could be done here, no doubt, and I hope someone will think about
how we can test these views more thoroughly. But this is a starting
point.
Discussion: https://postgr.es/m/19359.1485723741@sss.pgh.pa.us
