The idea here is that when a performance problem is known to have
occurred at a certain point in time, it's a good thing if there is
some information available from the logs to help figure out what
might have happened around that time.
This change attracted an above-average amount of dissent, because
it means that a server with default settings will produce some amount
of log output even if nothing has gone wrong. However, by my count,
the mailing list discussion had about twice as many people in favor
of the change as opposed. The reasons for believing that the extra
log output is not an issue in practice are: (1) the rate at which
messages can be generated by this setting is bounded to one every
few minutes on a properly-configured system and (2) production
systems tend to have a lot more junk in the log from that due to
failed connection attempts, ERROR messages generated by application
activity, and the like.
Bharath Rupireddy, reviewed by Fujii Masao and by me. Many other
people commented on the thread, but as far as I can see that was
discussion of the merits of the change rather than review of the
patch.
Discussion: https://postgr.es/m/CALj2ACX-rW_OeDcp4gqrFUAkf1f50Fnh138dmkd0JkvCNQRKGA@mail.gmail.com
This commit improves the description of some WAL records for the
Transaction RMGR:
- Track remote_apply for a transaction commit. This GUC is
user-settable, so this information can be useful for debugging.
- Add replication origin information for PREPARE TRANSACTION, with the
origin ID, LSN and timestamp
- Same as above, for ROLLBACK PREPARED.
This impacts the format of pg_waldump or anything using these
description routines, so no backpatch is done.
Author: Masahiko Sawada, Michael Paquier
Discussion: https://postgr.es/m/CAD21AoD2dJfgsdxk4_KciAZMZQoUiCvmV9sDpp8ZuKLtKCNXaA@mail.gmail.com
The term "super-exclusive lock" is a synonym for "buffer cleanup lock"
that first appeared in nbtree many years ago. Standardize things by
consistently using the term cleanup lock. This finishes work started by
commit 276db875.
There is no good reason to have two terms. But there is a good reason
to only have one: to avoid confusion around why VACUUM acquires a full
cleanup lock (not just an ordinary exclusive lock) in index AMs, during
ambulkdelete calls. This has nothing to do with protecting the physical
index data structure itself. It is needed to implement a locking
protocol that ensures that TIDs pointing to the heap/table structure
cannot get marked for recycling by VACUUM before it is safe (which is
somewhat similar to how VACUUM uses cleanup locks during its first heap
pass). Note that it isn't strictly necessary for index AMs to implement
this locking protocol -- several index AMs use an MVCC snapshot as their
sole interlock to prevent unsafe TID recycling.
In passing, update the nbtree README. Cleanly separate discussion of
the aforementioned index vacuuming locking protocol from discussion of
the "drop leaf page pin" optimization added by commit 2ed5b87f. We now
structure discussion of the latter by describing how individual index
scans may safely opt out of applying the standard locking protocol (and
so can avoid blocking progress by VACUUM). Also document why the
optimization is not safe to apply during nbtree index-only scans.
Author: Peter Geoghegan <pg@bowt.ie>
Discussion: https://postgr.es/m/CAH2-WzngHgQa92tz6NQihf4nxJwRzCV36yMJO_i8dS+2mgEVKw@mail.gmail.com
Discussion: https://postgr.es/m/CAH2-WzkHPgsBBvGWjz=8PjNhDefy7XRkDKiT5NxMs-n5ZCf2dA@mail.gmail.com
REINDEX CONCURRENTLY run on a toast index or a toast relation could
corrupt the target indexes rebuilt, as a backend running in parallel
that manipulates toast values would directly release the lock on the
toast relation when its local operation is done, rather than releasing
the lock once the transaction that manipulated the toast values
committed.
The fix done here is simple: we now hold a ROW EXCLUSIVE lock on the
toast relation when saving or deleting a toast value until the
transaction working on them is committed, so as a concurrent reindex
happening in parallel would be able to wait for any activity and see any
new rows inserted (or deleted).
An isolation test is added to check after the case fixed here, which is
a bit fancy by design as it relies on allow_system_table_mods to rename
the toast table and its index to fixed names. This way, it is possible
to reindex them directly without any dependency on the OID of the
underlying relation. Note that this could not use a DO block either, as
REINDEX CONCURRENTLY cannot be run in a transaction block. The test is
backpatched down to 13, where it is possible, thanks to c4a7a39, to use
allow_system_table_mods in a test suite.
Reported-by: Alexey Ermakov
Analyzed-by: Andres Freund, Noah Misch
Author: Michael Paquier
Reviewed-by: Nathan Bossart
Discussion: https://postgr.es/m/17268-d2fb426e0895abd4@postgresql.org
Backpatch-through: 12
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
Like 5364b357fb did for pg_commit, change the formula used to
determine number of pg_commit_ts buffers, which helps performance with
larger servers.
Discussion: https://postgr.es/m/20210115220744.GA24457@alvherre.pgsql
Reviewed-by: Noah Misch <noah@leadboat.com>
Reviewed-by: Tomas Vondra <tomas.vondra@enterprisedb.com>
Commit 8523492d simplified what it meant for an item to be considered
"dead" to VACUUM: TIDs collected in memory (in preparation for index
vacuuming) must always come from LP_DEAD stub line pointers in heap
pages, found following pruning. This formalized the idea that index
vacuuming (and heap vacuuming) are optional processes. Unlike pruning,
they can be delayed indefinitely, without any risk of that violating
fundamental invariants. For example, leaving LP_DEAD items behind
clearly won't add to the risk of transaction ID wraparound. You can't
have transaction ID wraparound without transaction IDs. Renaming
anything that references DEAD tuples (tuples with storage) reinforces
all this.
Code outside vacuumlazy.c continues to fudge the distinction between
dead/deleted tuples, and LP_DEAD items. This is necessary because
autovacuum scheduling is still mostly driven by "dead items/tuples"
statistics. In the future we may find it useful to replace this model
with something more sophisticated, as a step towards teaching autovacuum
to perform more frequent vacuuming that targeting individual indexes
that happen to be more prone to becoming bloated through version churn.
In passing, simplify some function signatures that deal with VACUUM's
dead_items array.
Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Masahiko Sawada <sawada.mshk@gmail.com>
Discussion: https://postgr.es/m/CAH2-WzktGBg4si6DEdmq3q6SoXSDqNi6MtmB8CmmTmvhsxDTLA@mail.gmail.com
This commit moves the timestamp computation of the control file within
the routine of src/common/ in charge of updating the backend's control
file, which is shared by multiple frontend tools (pg_rewind,
pg_checksums and pg_resetwal) and the backend itself.
This change has as direct effect to update the control file's timestamp
when writing the control file in pg_rewind and pg_checksums, something
that is helpful to keep track of control file updates for those
operations, something also tracked by the backend at startup within its
logs. This part is arguably a bug, as ControlFileData->time should be
updated each time a new version of the control file is written, but this
is a behavior change so no backpatch is done.
Author: Amul Sul
Reviewed-by: Nathan Bossart, Michael Paquier, Bharath Rupireddy
Discussion: https://postgr.es/m/CAAJ_b97nd_ghRpyFV9Djf9RLXkoTbOUqnocq11WGq9TisX09Fw@mail.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
The term "super-exclusive lock" is an acceptable synonym of "cleanup
lock". Even still, switching from one term to the other in the same
file is confusing. Standardize on "cleanup lock" within vacuumlazy.c.
Per a complaint from Andres Freund.
Update vacuumlazy.c file header comments (as well as comments above the
lazy_scan_heap function) that were largely written before the
introduction of the HOT optimization, when lazy_scan_heap did far less,
and didn't actually prune during its initial heap pass.
Since lazy_scan_heap now outsources far more work to lower level
functions, it makes sense to introduce the function by talking about the
high level invariant that dictates the order in which each phase takes
place. Also deemphasize the case where we run out of memory for TIDs,
since delaying that discussion makes it easier to talk about issues of
central importance.
Finally, remove discussion of parallel VACUUM from header comments.
These don't add much, and are in the wrong place.
Commit 2fd8685e7f simplified the checking of modified attributes that
takes place within heap_update(). This included a micro-optimization
affecting pages marked PD_PAGE_FULL: don't even try to use HOT to save a
few cycles on determining HOT safety. The assumption was that it won't
work out this time around, since it can't have worked out last time
around.
Remove the micro-optimization. It could only ever save cycles that are
consumed by the vast majority of heap_update() calls, which hardly seems
worth the added complexity. It also seems quite possible that there are
workloads that will do worse over time by repeated application of the
micro-optimization, despite saving some cycles on average, in the short
term.
Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/CAH2-WznU1L3+DMPr1F7o2eJBT7=3bAJoY6ZkWABAxNt+-afyTA@mail.gmail.com
In commit ff9f111bce I mixed up inconsistent definitions of the LSN of
the first record in a page, when the previous record ends exactly at the
page boundary. The correct LSN is adjusted to skip the WAL page header;
I failed to use that when setting XLogReaderState->overwrittenRecPtr,
so at WAL replay time VerifyOverwriteContrecord would refuse to let
replay continue past that record.
Backpatch to 10. 9.6 also contains this bug, but it's no longer being
maintained.
Discussion: https://postgr.es/m/45597.1637694259@sss.pgh.pa.us
Various places wanted to point out that tuple descriptors don't
contain the variable-length fields of pg_attribute. This started when
attacl was added, but more fields have been added since, and these
comments haven't been kept up to date consistently. Reword so that
the purpose is clearer and we don't have to keep updating them.
In most places, the variables necessarily store the same value as the
eponymous members of the XLogReaderState that we use during WAL
replay, because ReadRecord() assigns the values from the structure
members to the global variables just after XLogReadRecord() returns.
However, XLogBeginRead() adjusts the structure members but not the
global variables, so after XLogBeginRead() and before the completion
of XLogReadRecord() the values can differ. Otherwise, they must be
identical. According to my analysis, the only place where either
variable is referenced at a point where it might not have the same
value as the structure member is the refrence to EndRecPtr within
XLogPageRead.
Therefore, at every other place where we are using the global
variable, we can just switch to using the structure member instead,
and remove the global variable. However, we can, and in fact should,
do this in XLogPageRead() as well, because at that point in the code,
the global variable will actually store the start of the record we
want to read - either because it's where the last WAL record ended, or
because the read position has been changed using XLogBeginRead since
the last record was read. The structure member, on the other hand,
will already have been updated to point to the end of the record we
just read. Elsewhere, the latter is what we use as an argument to
emode_for_corrupt_record(), so we should do the same here.
This part of the patch is perhaps a bug fix, but I don't think it has
any important consequences, so no back-patch. The point here is just
to continue to whittle down the entirely excessive use of global
variables in xlog.c.
Discussion: http://postgr.es/m/CA+Tgmoao96EuNeSPd+hspRKcsCddu=b1h-QNRuKfY8VmfNQdfg@mail.gmail.com
rescanLatestTimeLine() contains a guard against switching to
a timeline that forked off from the current one prior to the
current recovery point, but that guard does not work if the
timeline switch occurs before the first WAL recod (which must
be the checkpoint record) is read. Without this patch, an
improper timeline switch is therefore possible in such cases.
This happens because rescanLatestTimeLine() relies on the global
variable EndRecPtr to understand the current position of WAL
replay. However, EndRecPtr at this point in the code contains
the endpoint of the last-replayed record, not the startpoint or
endpoint of the record being replayed now. Thus, before any
records have been replayed, it's zero, which causes the sanity
check to always pass.
To fix, pass down the correct timeline explicitly. The
EndRecPtr value we want is the one from the xlogreader, which
will be the starting position of the record we're about to
try to read, rather than the global variable, which is the
ending position of the last record we successfully read.
They're usually the same, but not in the corner case described
here.
No back-patch, because in v14 and earlier branhes, we were using
the wrong TLI here as well as the wrong LSN. In master, that was
fixed by commit 4a92a1c3d1, but
that and it's prerequisite patches are too invasive to
back-patch for such a minor issue.
Patch by me, reviewed by Amul Sul.
Discussion: http://postgr.es/m/CA+Tgmoao96EuNeSPd+hspRKcsCddu=b1h-QNRuKfY8VmfNQdfg@mail.gmail.com
A couple of spots can benefit from an added errdetail(), which matches
what we were already doing in other places; and those that cannot
withstand errdetail() can get a more descriptive primary message.
Author: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Reviewed-by: Julien Rouhaud <rjuju123@gmail.com>
Discussion: https://postgr.es/m/CALj2ACV+cX1eM03GfcA=ZMLXh5fSn1X1auJLz3yuS1duPSb9QA@mail.gmail.com
This doesn't belong next to very high level discussion of the tasks that
lazy_scan_heap performs. There is already a similar, longer comment
block at the top of vacuumlazy.c that mentions lazy_scan_heap directly.
Commit ac9099fc1 rearranged the logic in spgGetCache() that determines
the index's attType (nominal input data type) and leafType (actual
type stored in leaf index tuples). Turns out this broke things for
the case where (a) the actual input data type is different from the
nominal type, (b) the opclass's config function leaves leafType
defaulted, and (c) the opclass has no "compress" function. (b) caused
us to assign the actual input data type as leafType, and then since
that's not attType, we complained that a "compress" function is
required. For non-polymorphic opclasses, condition (a) arises in
binary-compatible cases, such as using SP-GiST text_ops for a varchar
column, or using any opclass on a domain over its nominal input type.
To fix, use attType for leafType when the index's declared column type
is different from but binary-compatible with attType. Do this only in
the defaulted-leafType case, to avoid overriding any explicit
selection made by the opclass.
Per bug #17294 from Ilya Anfimov. Back-patch to v14.
Discussion: https://postgr.es/m/17294-8f6c7962ce877edc@postgresql.org
While determining xid horizons, we skip over backends that are running
Vacuum. We also ignore Create Index Concurrently, or Reindex Concurrently
for the purposes of computing Xmin for Vacuum. But we were not setting the
flags corresponding to these operations when they are performed in
parallel which was preventing Xid horizon from advancing.
The optimization related to skipping Create Index Concurrently, or Reindex
Concurrently operations was implemented in PG-14 but the fix is the same
for the Parallel Vacuum as well so back-patched till PG-13.
Author: Masahiko Sawada
Reviewed-by: Amit Kapila
Backpatch-through: 13
Discussion: https://postgr.es/m/CAD21AoCLQqgM1sXh9BrDFq0uzd3RBFKi=Vfo6cjjKODm0Onr5w@mail.gmail.com
At present, there is an undocumented coding rule that you must call
RecoveryInProgress(), or do something else that results in a call
to InitXLogInsert(), before trying to write WAL. Otherwise, the
WAL construction buffers won't be initialized, resulting in
failures.
Since it's not good to rely on a status inquiry function like
RecoveryInProgress() having the side effect of initializing
critical data structures, instead do the initialization eariler,
when the backend first starts up.
Patch by me. Reviewed by Nathan Bossart and Michael Paquier.
Discussion: http://postgr.es/m/CA+TgmoY7b65qRjzHN_tWUk8B4sJqk1vj1d31uepVzmgPnZKeLg@mail.gmail.com
Add a comment explaining why the pgstats accounting used during
opportunistic heap pruning operations (to maintain the current number of
dead tuples in the relation) needs to compensate by subtracting away the
number of new LP_DEAD items. This is needed so it can avoid completely
forgetting about tuples that become LP_DEAD items during pruning -- they
should still count.
It seems more natural to discuss this issue at the only relevant call
site (opportunistic pruning), since the same issue does not apply to the
only other caller (the VACUUM call site). Move everything there too.
Author: Peter Geoghegan <pg@bowt.ie>
Discussion: https://postgr.es/m/CAH2-Wzm7f+A6ej650gi_ifTgbhsadVW5cujAL3punpupHff5Yg@mail.gmail.com
Buildfarm members kittiwake and tadarida have witnessed errors at this
site. The site discarded key facts. Back-patch to v10 (all supported
versions).
Reviewed by Michael Paquier and Tom Lane.
Discussion: https://postgr.es/m/20211107013157.GB790288@rfd.leadboat.com
It is up to the heap_page_prune() caller to decide what to do about
updating the FSM for a page following pruning. Update old comments that
address what we might want to do as if it was the responsibility of
heap_page_prune() itself. heap_page_prune() doesn't have enough
high-level context to make a sensible choice.
Presently, the archive_status directory was scanned for each file to
archive. When there are many status files, say because archive_command
has been failing for a long time, these directory scans can get very
slow. With this change, the archiver remembers several files to archive
during each directory scan, speeding things up.
To ensure timeline history files are archived as quickly as possible,
XLogArchiveNotify() forces the archiver to do a new directory scan as
soon as the .ready file for one is created.
Nathan Bossart, per a long discussion involving many people. It is
not clear to me exactly who out of all those people reviewed this
particular patch.
Discussion: http://postgr.es/m/CA+TgmobhAbs2yabTuTRkJTq_kkC80-+jw=pfpypdOJ7+gAbQbw@mail.gmail.com
Discussion: http://postgr.es/m/620F3CE1-0255-4D66-9D87-0EADE866985A@amazon.com
In XLogCtlData, rename the structure member ThisTimeLineID to
InsertTimeLineID and update the comments to make clear that it's only
expected to be set after recovery is complete.
In StartupXLOG, replace the local variables ThisTimeLineID and
PrevTimeLineID with new local variables replayTLI and newTLI. In the
old scheme, ThisTimeLineID was the replay TLI until we created a new
timeline, and after that the replay TLI was in PrevTimeLineID. Now,
replayTLI is the TLI from which we last replayed WAL throughout the
entire function, and newTLI is either that, or the new timeline created
upon promotion.
Remove some misleading comments from the comment block just above where
recoveryTargetTimeLineGoal and friends are declared. It's become
incorrect, not only because ThisTimeLineID as a variable is now gone,
but also because the rmgr code does not care about ThisTimeLineID and
has not since what used to be the TLI field in the page header was
repurposed to store the page checksum.
Add a comment GetFlushRecPtr that it's only supposed to be used in
normal running, and an assertion to verify that this is so.
Per some ideas from Michael Paquier and some of my own. Review by
Michael Paquier also.
Discussion: http://postgr.es/m/CA+TgmoY1a2d1AnVR3tJcKmGGkhj7GGrwiNwjtKr21dxOuLBzCQ@mail.gmail.com
Quite a few buildfarm animals are warning about this, and lapwing
is actually failing (because -Werror). It's a false positive AFAICS,
so no need to do more than zero the variable to start with.
Discussion: https://postgr.es/m/YYXJnUxgw9dZKxlX@paquier.xyz
When calculating distance between float4/float8 values, we need to be a
bit more careful about NaN values in order not to trigger assert. We
consider NaN values to be equal (distace 0.0) and in infinite distance
from all other values.
On builds without asserts, this issue is mostly harmless - the ranges
may be merged in less efficient order, but the index is still correct.
Per report from Andreas Seltenreich. Backpatch to 14, where this new
BRIN opclass was introduced.
Reported-by: Andreas Seltenreich
Discussion: https://postgr.es/m/87r1bw9ukm.fsf@credativ.de
Add new comments that spell out what VACUUM expects from heap pruning:
pruning must never leave behind DEAD tuples that still have tuple
storage. This has at least been the case since commit 8523492d, which
established the principle that vacuumlazy.c doesn't have to deal with
DEAD tuples that still have tuple storage directly, except perhaps by
simply retrying pruning (to handle a rare corner case involving
concurrent transaction abort).
In passing, update some references to old symbol names that were missed
by the snapshot scalability work (specifically commit dc7420c2c9).
StartupXLOG() still has ThisTimeLineID as a local variable, but the
remaining code in xlog.c now needs to the relevant TimeLineID by some
other means. Mostly, this means that we now pass it as a function
parameter to a bunch of functions where we didn't previously.
However, a few cases require special handling:
- In functions that might be called by outside callers who
wouldn't necessarily know what timeline to specify, we get
the timeline ID from shared memory. XLogCtl->ThisTimeLineID
can be used in most cases since recovery is known to have
completed by the time those functions are called. In
xlog_redo(), we can use XLogCtl->replayEndTLI.
- XLogFileClose() needs to know the TLI of the open logfile.
Do that with a new global variable openLogTLI. While
someone could argue that this is just trading one global
variable for another, the new one has a far more narrow
purposes and is referenced in just a few places.
- read_backup_label() now returns the TLI that it obtains
by parsing the backup_label file. Previously, ReadRecord()
could be called to parse the checkpoint record without
ThisTimeLineID having been initialized. Now, the timeline
is passed down, and I didn't want to pass an uninitialized
variable; this change lets us avoid that. The old coding
didn't seem to have any practical consequences that we need
to worry about, but this is cleaner.
- In BootstrapXLOG(), it's just a constant.
Patch by me, reviewed and tested by Michael Paquier, Amul Sul, and
Álvaro Herrera.
Discussion: https://postgr.es/m/CA+TgmobfAAqhfWa1kaFBBFvX+5CjM=7TE=n4r4Q1o2bjbGYBpA@mail.gmail.com
All such code deals with this global variable in one of three ways.
Sometimes the same functions use it in more than one of these ways
at the same time.
First, sometimes it's an implicit argument to one or more functions
being called in xlog.c or elsewhere, and must be set to the
appropriate value before calling those functions lest they
misbehave. In those cases, it is now passed as an explicit argument
instead.
Second, sometimes it's used to obtain the current timeline after
the end of recovery, i.e. the timeline to which WAL is being
written and flushed. Such code now calls GetWALInsertionTimeLine()
or relies on the new out parameter added to GetFlushRecPtr().
Third, sometimes it's used during recovery to store the current
replay timeline. That can change, so such code must generally
update the value before each use. It can still do that, but must
now use a local variable instead.
The net effect of these changes is to reduce by a fair amount the
amount of code that is directly accessing this global variable.
That's good, because history has shown that we don't always think
clearly about which timeline ID it's supposed to contain at any
given point in time, or indeed, whether it has been or needs to
be initialized at any given point in the code.
Patch by me, reviewed and tested by Michael Paquier, Amul Sul, and
Álvaro Herrera.
Discussion: https://postgr.es/m/CA+TgmobfAAqhfWa1kaFBBFvX+5CjM=7TE=n4r4Q1o2bjbGYBpA@mail.gmail.com
Add hardening to the heapam index tuple deletion path to catch TIDs in
index pages that point to a heap item that index tuples should never
point to. The corruption we're trying to catch here is particularly
tricky to detect, since it typically involves "extra" (corrupt) index
tuples, as opposed to the absence of required index tuples in the index.
For example, a heap TID from an index page that turns out to point to an
LP_UNUSED item in the heap page has a good chance of being caught by one
of the new checks. There is a decent chance that the recently fixed
parallel VACUUM bug (see commit 9bacec15) would have been caught had
that particular check been in place for Postgres 14. No backpatch of
this extra hardening for now, though.
Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/CAH2-Wzk-4_raTzawWGaiqNvkpwDXxv3y1AQhQyUeHfkU=tFCeA@mail.gmail.com
These assertions document (and verify) our high level assumptions about
how pruning can and cannot affect existing items from target heap pages.
For example, one of the new assertions verifies that pruning does not
set a heap-only tuple to LP_DEAD.
Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/CAH2-Wz=vhvBx1GjF+oueHh8YQcHoQYrMi0F0zFMHEr8yc4sCoA@mail.gmail.com
Commit b4af70cb inverted the return value of the function
parallel_processing_is_safe(), but missed the amvacuumcleanup test.
Index AMs that don't support parallel cleanup at all were affected.
The practical consequences of this bug were not very serious. Hash
indexes are affected, but since they just return the number of blocks
during hashvacuumcleanup anyway, it can't have had much impact.
Author: Masahiko Sawada <sawada.mshk@gmail.com>
Discussion: https://postgr.es/m/CAD21AoA-Em+aeVPmBbL_s1V-ghsJQSxYL-i3JP8nTfPiD1wjKw@mail.gmail.com
Backpatch: 14-, where commit b4af70cb appears.
Commit b4af70cb, which simplified state managed by VACUUM, performed
refactoring of parallel VACUUM in passing. Confusion about the exact
details of the tasks that the leader process is responsible for led to
code that made it possible for parallel VACUUM to miss a subset of the
table's indexes entirely. Specifically, indexes that fell under the
min_parallel_index_scan_size size cutoff were missed. These indexes are
supposed to be vacuumed by the leader (alongside any parallel unsafe
indexes), but weren't vacuumed at all. Affected indexes could easily
end up with duplicate heap TIDs, once heap TIDs were recycled for new
heap tuples. This had generic symptoms that might be seen with almost
any index corruption involving structural inconsistencies between an
index and its table.
To fix, make sure that the parallel VACUUM leader process performs any
required index vacuuming for indexes that happen to be below the size
cutoff. Also document the design of parallel VACUUM with these
below-size-cutoff indexes.
It's unclear how many users might be affected by this bug. There had to
be at least three indexes on the table to hit the bug: a smaller index,
plus at least two additional indexes that themselves exceed the size
cutoff. Cases with just one additional index would not run into
trouble, since the parallel VACUUM cost model requires two
larger-than-cutoff indexes on the table to apply any parallel
processing. Note also that autovacuum was not affected, since it never
uses parallel processing.
Test case based on tests from a larger patch to test parallel VACUUM by
Masahiko Sawada.
Many thanks to Kamigishi Rei for her invaluable help with tracking this
problem down.
Author: Peter Geoghegan <pg@bowt.ie>
Author: Masahiko Sawada <sawada.mshk@gmail.com>
Reported-By: Kamigishi Rei <iijima.yun@koumakan.jp>
Reported-By: Andrew Gierth <andrew@tao11.riddles.org.uk>
Diagnosed-By: Andres Freund <andres@anarazel.de>
Bug: #17245
Discussion: https://postgr.es/m/17245-ddf06aaf85735f36@postgresql.org
Discussion: https://postgr.es/m/20211030023740.qbnsl2xaoh2grq3d@alap3.anarazel.de
Backpatch: 14-, where the refactoring commit appears.
We don't modify any shared state in this function which could cause
problems for any concurrent session. This will make it look similar to the
other updates for the same structure (TransactionState) which avoids
confusion for future readers of code.
Author: Dilip Kumar
Reviewed-by: Amit Kapila
Discussion: https://postgr.es/m/E1mSoYz-0007Fh-D9@gemulon.postgresql.org
Commit 0bead9af48 introduced XLOG_INCLUDE_XID flag to indicate that the
WAL record contains subXID-to-topXID association. It uses that flag later
to mark in CurrentTransactionState that top-xid is logged so that we
should not try to log it again with the next WAL record in the current
subtransaction. However, we can use a localized variable to pass that
information.
In passing, change the related function and variable names to make them
consistent with what the code is actually doing.
Author: Dilip Kumar
Reviewed-by: Alvaro Herrera, Amit Kapila
Discussion: https://postgr.es/m/E1mSoYz-0007Fh-D9@gemulon.postgresql.org
The unicode characters, while in comments and not code, caused MSVC
to emit compiler warning C4819:
The file contains a character that cannot be represented in the
current code page (number). Save the file in Unicode format to
prevent data loss.
Fix by replacing the characters in print.c with descriptive comments
containing the codepoints and symbol names, and remove the character
in brin_bloom.c which was a footnote reference copied from the paper
citation.
Per report from hamerkop in the buildfarm.
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/340E4118-0D0C-4E85-8141-8C40EB22DA3A@yesql.se
Commit d168b66682, which overhauled index deletion, added a
pg_unreachable() to the end of a sort comparator used when sorting heap
TIDs from an index page. This allows the compiler to apply
optimizations that assume that the heap TIDs from the index AM must
always be unique.
That doesn't seem like a good idea now, given recent reports of
corruption involving duplicate TIDs in indexes on Postgres 14. Demote
to an assertion, just in case.
Backpatch: 14-, where index deletion was overhauled.
Comments above _bt_findinsertloc() that talk about LP_DEAD items are now
out of place. We already discuss index tuple deletion at an earlier
point in the same comment block.
Oversight in commit d168b666.
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
All the code that runs in the startup process to write WAL records
before that's allowed generally is now consecutive, so there's no
reason to shut the facility to write WAL locally off and then turn
it on again three times in a row.
Unfortunately, this requires a slight kludge in the checkpointer,
which needs to separately enable writing WAL in order to write the
checkpoint record. Because that code might run in the same process
as StartupXLOG() if we are in single-user mode, we must save/restore
the state of the LocalXLogInsertAllowed flag. Hopefully, we'll be
able to eliminate this wart in further refactoring, but it's
not too bad anyway.
Amul Sul, with modifications by me.
Discussion: http://postgr.es/m/CAAJ_b97fysj6sRSQEfOHj-y8Jfd5uPqOgO74qast89B4WfD+TA@mail.gmail.com
This does a better job grouping related operations together, since
all of the WAL records that we need to write prior to allowing WAL
writes generally and written by a single uninterrupted stretch of code.
Since CleanupAfterArchiveRecovery() just (1) runs recovery_end_command,
(2) removes non-parent xlog files, and (3) archives any final partial
segment, this should be safe, because all of those things are pretty
much unrelated to the WAL record written by XLogReportParameters().
Amul Sul, per a suggestion from me
Discussion: http://postgr.es/m/CAAJ_b97fysj6sRSQEfOHj-y8Jfd5uPqOgO74qast89B4WfD+TA@mail.gmail.com
The purpose of commit 8a54e12a38 was to
fix this, and it sufficed when the PREPARE TRANSACTION completed before
the CIC looked for lock conflicts. Otherwise, things still broke. As
before, in a cluster having used CIC while having enabled prepared
transactions, queries that use the resulting index can silently fail to
find rows. It may be necessary to reindex to recover from past
occurrences; REINDEX CONCURRENTLY suffices. Fix this for future index
builds by making CIC wait for arbitrarily-recent prepared transactions
and for ordinary transactions that may yet PREPARE TRANSACTION. As part
of that, have PREPARE TRANSACTION transfer locks to its dummy PGPROC
before it calls ProcArrayClearTransaction(). Back-patch to 9.6 (all
supported versions).
Andrey Borodin, reviewed (in earlier versions) by Andres Freund.
Discussion: https://postgr.es/m/01824242-AA92-4FE9-9BA7-AEBAFFEA3D0C@yandex-team.ru
During a replication slot creation, an ERROR generated in the same
transaction as the one creating a to-be-exported snapshot would have
left the backend in an inconsistent state, as the associated static
export snapshot state was not being reset on transaction abort, but only
on the follow-up command received by the WAL sender that created this
snapshot on replication slot creation. This would trigger inconsistency
failures if this session tried to export again a snapshot, like during
the creation of a replication slot.
Note that a snapshot export cannot happen in a transaction block, so
there is no need to worry resetting this state for subtransaction
aborts. Also, this inconsistent state would very unlikely show up to
users. For example, one case where this could happen is an
out-of-memory error when building the initial snapshot to-be-exported.
Dilip found this problem while poking at a different patch, that caused
an error in this code path for reasons unrelated to HEAD.
Author: Dilip Kumar
Reviewed-by: Michael Paquier, Zhihong Yu
Discussion: https://postgr.es/m/CAFiTN-s0zA1Kj0ozGHwkYkHwa5U0zUE94RSc_g81WrpcETB5=w@mail.gmail.com
Backpatch-through: 9.6
CreateOverwriteContrecordRecord(), UpdateFullPageWrites(),
PerformRecoveryXLogAction(), and CleanupAfterArchiveRecovery()
are moved somewhat later in StartupXLOG(). This is preparatory
work for a future patch that wants to allow recovery to end at one
time and only later start to allow WAL writes. To do that, it's
necessary to separate code that has to do with allowing WAL writes
from other things that need to happen simply because recovery is
ending, such as initializing shared memory data structures that
depend on information that might not be accurate before redo is
complete.
This commit does not achieve that goal, but it is a step in that
direction. For example, there are a few different bits of code that
write things into WAL once we have finished recovery, and with this
change, those bits of code are closer to each other than previously,
with fewer unrelated bits of code interspersed.
Robert Haas and Amul Sul
Discussion: http://postgr.es/m/CAAJ_b97abMuq=470Wahun=aS1PHTSbStHtrjjPaD-C0YQ1AqVw@mail.gmail.com
Create a new function PerformRecoveryXLogAction() and move the
code which either writes an end-of-recovery record or requests a
checkpoint there.
Also create a new function CleanupAfterArchiveRecovery() to
perform a few tasks that we want to do after we've actually exited
archive recovery but before we start accepting new WAL writes.
More refactoring of this file is planned, but this commit is
just straightforward code movement to make StartupXLOG() a
little bit shorter and a little bit easier to understand.
Robert Haas and Amul Sul
Discussion: http://postgr.es/m/CAAJ_b97abMuq=470Wahun=aS1PHTSbStHtrjjPaD-C0YQ1AqVw@mail.gmail.com
Commit 0668719801 changed XLogPageRead() so that it validated the page
header, if invalid page header was found reset the error message and
retried reading the page, to fix the scenario where streaming standby
got stuck at a continuation record. This change hid the error message
about invalid page header, which would make it harder for users to
investigate what the actual issue was found in WAL.
To fix the issue, this commit makes XLogPageRead() report the error
message when invalid page header is found.
When not in standby mode, an invalid page header should cause recovery
to end, not retry reading the page, so XLogPageRead() doesn't need to
validate the page header for the retry. Instead, ReadPageInternal() should
be responsible for the validation in that case. Therefore this commit
changes XLogPageRead() so that if not in standby mode it doesn't validate
the page header for the retry.
Reported-by: Yugo Nagata
Author: Yugo Nagata, Kyotaro Horiguchi
Reviewed-by: Ranier Vilela, Fujii Masao
Discussion: https://postgr.es/m/20210718045505.32f463ed6c227111038d8ae4@sraoss.co.jp
Some specific logic is done at the end of recovery when involving 2PC
transactions:
1) Call RecoverPreparedTransactions(), to recover the state of 2PC
transactions into memory (re-acquire locks, etc.).
2) ShutdownRecoveryTransactionEnvironment(), to move back to normal
operations, mainly cleaning up recovery locks and KnownAssignedXids
(including any 2PC transaction tracked previously).
3) Switch XLogCtl->SharedRecoveryState to RECOVERY_STATE_DONE, which is
the tipping point for any process calling RecoveryInProgress() to check
if the cluster is still in recovery or not.
Any snapshot taken between steps 2) and 3) would be empty, causing any
transaction relying on a snapshot at this point to potentially corrupt
data as there could still be some 2PC transactions to track, with
RecentXmin moving backwards on successive calls to GetSnapshotData() in
the same transaction.
As SharedRecoveryState is the point to take into account to know if it
is safe to discard KnownAssignedXids, this commit moves step 2) after
step 3), so as we can never finish with empty snapshots.
This exists since the introduction of hot standby, so backpatch all the
way down. The window with incorrect snapshots is extremely small, but I
have seen it when running 023_pitr_prepared_xact.pl, as did buildfarm
member fairywren. Thomas Munro also found it independently. Special
thanks to Andres Freund for taking the time to analyze this issue.
Reported-by: Thomas Munro, Michael Paquier
Analyzed-by: Andres Freund
Discussion: https://postgr.es/m/20210422203603.fdnh3fu2mmfp2iov@alap3.anarazel.de
Backpatch-through: 9.6
The "equality implies image equality" opclass infrastructure disallowed
deduplication in system catalog indexes and TOAST indexes before now.
That seemed like the right approach back when the infrastructure was
added by commit 612a1ab7, since ALTER INDEX cannot set deduplicate_items
to 'off' (due to an old implementation restriction). But that decision
now seems arbitrary at best. Remove special case handling implementing
this policy.
No catversion bump, since existing catalog indexes will still work.
Author: Peter Geoghegan <pg@bowt.ie>
Discussion: https://postgr.es/m/CAH2-Wz=rYQHFaJ3WYBdK=xgwxKzaiGMSSrh-ZCREa-pS-7Zjew@mail.gmail.com
Commit ff9f111bce added some test code that's unportable and doesn't
add meaningful coverage. Remove it rather than try and get it to work
everywhere.
While at it, fix a typo in a log message added by the aforementioned
commit.
Backpatch to 14.
Discussion: https://postgr.es/m/3000074.1632947632@sss.pgh.pa.us
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
Physical replication always ships WAL segment files to replicas once
they are complete. This is a problem if one WAL record is split across
a segment boundary and the primary server crashes before writing down
the segment with the next portion of the WAL record: WAL writing after
crash recovery would happily resume at the point where the broken record
started, overwriting that record ... but any standby or backup may have
already received a copy of that segment, and they are not rewinding.
This causes standbys to stop following the primary after the latter
crashes:
LOG: invalid contrecord length 7262 at A8/D9FFFBC8
because the standby is still trying to read the continuation record
(contrecord) for the original long WAL record, but it is not there and
it will never be. A workaround is to stop the replica, delete the WAL
file, and restart it -- at which point a fresh copy is brought over from
the primary. But that's pretty labor intensive, and I bet many users
would just give up and re-clone the standby instead.
A fix for this problem was already attempted in commit 515e3d84a0, but
it only addressed the case for the scenario of WAL archiving, so
streaming replication would still be a problem (as well as other things
such as taking a filesystem-level backup while the server is down after
having crashed), and it had performance scalability problems too; so it
had to be reverted.
This commit fixes the problem using an approach suggested by Andres
Freund, whereby the initial portion(s) of the split-up WAL record are
kept, and a special type of WAL record is written where the contrecord
was lost, so that WAL replay in the replica knows to skip the broken
parts. With this approach, we can continue to stream/archive segment
files as soon as they are complete, and replay of the broken records
will proceed across the crash point without a hitch.
Because a new type of WAL record is added, users should be careful to
upgrade standbys first, primaries later. Otherwise they risk the standby
being unable to start if the primary happens to write such a record.
A new TAP test that exercises this is added, but the portability of it
is yet to be seen.
This has been wrong since the introduction of physical replication, so
backpatch all the way back. In stable branches, keep the new
XLogReaderState members at the end of the struct, to avoid an ABI
break.
Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Reviewed-by: Nathan Bossart <bossartn@amazon.com>
Discussion: https://postgr.es/m/202108232252.dh7uxf6oxwcy@alvherre.pgsql
Discussing the low level issue of nbtree VACUUM and recovery conflicts
in btvacuumpage() now seems inappropriate. The same issue is discussed
in nbtxlog.h, as well as in a comment block above _bt_delitems_vacuum().
The comment block made more sense when it was part of a broader
discussion of nbtree VACUUM "pin scans". These were removed by commit
9f83468b.
_bt_delitems_delete() is no longer the high-level entry point used by
index tuple deletion driven by index tuples whose LP_DEAD bits are set
(now called "simple index tuple deletion"). It became a lower level
routine that's only called by _bt_delitems_delete_check() following
commit d168b66682.
Remove obsolete reference to lazy_vacuum()'s onecall argument. The
function argument was removed by commit 3499df0dee.
Also remove adjoining comment block that introduces the wraparound
failsafe concept. Talking about the failsafe here no longer makes
sense, since lazy_vacuum() (and related functions) are no longer the
only place where the failsafe might be triggered. This has been the
case since commit c242baa4a8 taught VACUUM to consider triggering the
failsafe mechanism during its initial heap scan.
Point out that index tuple deletion generally needs a latestRemovedXid
value for the deletion operation's WAL record. This is bound to be the
most expensive part of the whole deletion operation now that it takes
place up front, during original execution.
This was arguably an oversight in commit 558a9165e0, which moved the
work required to generate these values from index deletion REDO routines
to original execution of index deletion operations.
Checking that an offset number isn't past the end of a heap page's line
pointer array was just a defensive sanity check for HOT-chain traversal
code before commit 3c3b8a4b. It's etrictly necessary now, though. Add
comments that reference the issue to code in heapam that needs to get it
right.
Per suggestion from Alexander Lakhin.
Discussion: https://postgr.es/m/f76a292c-9170-1aef-91a0-59d9443b99a3@gmail.com
It is not appropriate for deduplication to apply single value strategy
when triggered by a bottom-up index deletion pass. This wastes cycles
because later bottom-up deletion passes will overinterpret older
duplicate tuples that deduplication actually just skipped over "by
design". It also makes bottom-up deletion much less effective for low
cardinality indexes that happen to cross a meaningless "index has single
key value per leaf page" threshold.
To fix, slightly narrow the conditions under which deduplication's
single value strategy is considered. We already avoided the strategy
for a unique index, since our high level goal must just be to buy time
for VACUUM to run (not to buy space). We'll now also avoid it when we
just had a bottom-up pass that reported failure. The two cases share
the same high level goal, and already overlapped significantly, so this
approach is quite natural.
Oversight in commit d168b666, which added bottom-up index deletion.
Author: Peter Geoghegan <pg@bowt.ie>
Discussion: https://postgr.es/m/CAH2-WznaOvM+Gyj-JQ0X=JxoMDxctDTYjiEuETdAGbF5EUc3MA@mail.gmail.com
Backpatch: 14-, where bottom-up deletion was introduced.
I noticed that commit 0bead9af48 left this flag undocumented in
XLogSetRecordFlags, which led me to discover that the flag doesn't
actually do what the one comment on it said it does. Improve the
situation by adding some more comments.
Backpatch to 14, where the aforementioned commit appears.
Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/202109212119.c3nhfp64t2ql@alvherre.pgsql
A broken HOT chain is not an unexpected condition, even when the offset
number points past the end of the page's line pointer array.
heap_prune_chain() does not (and never has) treated this condition as
unexpected, so derivative code in heap_index_delete_tuples() shouldn't
do so either.
Oversight in commit 4228817449.
The assertion can probably only fail on Postgres 14 and master. Earlier
releases don't have commit 3c3b8a4b, which taught VACUUM to truncate the
line pointer array of heap pages. Backpatch all the same, just to be
consistent.
Author: Peter Geoghegan <pg@bowt.ie>
Reported-By: Alexander Lakhin <exclusion@gmail.com>
Discussion: https://postgr.es/m/17197-9438f31f46705182@postgresql.org
Backpatch: 12-, just like commit 4228817449.
Formerly, we sent signals for outgoing NOTIFY messages within
ProcessCompletedNotifies, which was also responsible for sending
relevant ones of those messages to our connected client. It therefore
had to run during the main-loop processing that occurs just before
going idle. This arrangement had two big disadvantages:
* Now that procedures allow intra-command COMMITs, it would be
useful to send NOTIFYs to other sessions immediately at COMMIT
(though, for reasons of wire-protocol stability, we still shouldn't
forward them to our client until end of command).
* Background processes such as replication workers would not send
NOTIFYs at all, since they never execute the client communication
loop. We've had requests to allow triggers running in replication
workers to send NOTIFYs, so that's a problem.
To fix these things, move transmission of outgoing NOTIFY signals
into AtCommit_Notify, where it will happen during CommitTransaction.
Also move the possible call of asyncQueueAdvanceTail there, to
ensure we don't bloat the async SLRU if a background worker sends
many NOTIFYs with no one listening.
We can also drop the call of asyncQueueReadAllNotifications,
allowing ProcessCompletedNotifies to go away entirely. That's
because commit 790026972 added a call of ProcessNotifyInterrupt
adjacent to PostgresMain's call of ProcessCompletedNotifies,
and that does its own call of asyncQueueReadAllNotifications,
meaning that we were uselessly doing two such calls (inside two
separate transactions) whenever inbound notify signals coincided
with an outbound notify. We need only set notifyInterruptPending
to ensure that ProcessNotifyInterrupt runs, and we're done.
The existing documentation suggests that custom background workers
should call ProcessCompletedNotifies if they want to send NOTIFY
messages. To avoid an ABI break in the back branches, reduce it
to an empty routine rather than removing it entirely. Removal
will occur in v15.
Although the problems mentioned above have existed for awhile,
I don't feel comfortable back-patching this any further than v13.
There was quite a bit of churn in adjacent code between 12 and 13.
At minimum we'd have to also backpatch 51004c717, and a good deal
of other adjustment would also be needed, so the benefit-to-risk
ratio doesn't look attractive.
Per bug #15293 from Michael Powers (and similar gripes from others).
Artur Zakirov and Tom Lane
Discussion: https://postgr.es/m/153243441449.1404.2274116228506175596@wrigleys.postgresql.org
All the code paths simplified here were already using a boolean or used
an expression that led to zero or one, making the extra bits
unnecessary.
Author: Justin Pryzby
Reviewed-by: Tom Lane, Michael Paquier, Peter Smith
Discussion: https://postgr.es/m/20210428182936.GE27406@telsasoft.com
Attempting to make hashfloat4() look as much as possible like
hashfloat8(), I'd figured I could replace NaNs with get_float4_nan()
before widening to float8. However, results from protosciurus
and topminnow show that on some platforms that produces a different
bit-pattern from get_float8_nan(), breaking the intent of ce773f230.
Rearrange so that we use the result of get_float8_nan() for all NaN
cases. As before, back-patch.
The IEEE 754 standard allows a wide variety of bit patterns for NaNs,
of which at least two ("NaN" and "-NaN") are pretty easy to produce
from SQL on most machines. This is problematic because our btree
comparison functions deem all NaNs to be equal, but our float hash
functions know nothing about NaNs and will happily produce varying
hash codes for them. That causes unexpected results from queries
that hash a column containing different NaN values. It could also
produce unexpected lookup failures when using a hash index on a
float column, i.e. "WHERE x = 'NaN'" will not find all the rows
it should.
To fix, special-case NaN in the float hash functions, not too much
unlike the existing special case that forces zero and minus zero
to hash the same. I arranged for the most vanilla sort of NaN
(that coming from the C99 NAN constant) to still have the same
hash code as before, to reduce the risk to existing hash indexes.
I dithered about whether to back-patch this into stable branches,
but ultimately decided to do so. It's a clear improvement for
queries that hash internally. If there is anybody who has -NaN
in a hash index, they'd be well advised to re-index after applying
this patch ... but the misbehavior if they don't will not be much
worse than the misbehavior they had before.
Per bug #17172 from Ma Liangzhu.
Discussion: https://postgr.es/m/17172-7505bea9e04e230f@postgresql.org
It doesn't make any sense to report this information, since VACUUM
VERBOSE reports on heap relation truncation directly. This was an
oversight in commit 7ab96cf6, which made VACUUM VERBOSE output a little
more consistent with nearby autovacuum-specific log output. Adjust
comments that describe how this is supposed to work in passing.
Also bring truncation-related VACUUM VERBOSE output in line with the
convention established for VACUUM VERBOSE output by commit f4f4a649.
Author: Peter Geoghegan <pg@bowt.ie>
Backpatch: 14-, where VACUUM VERBOSE's output changed.
The field hasn't been used since commit 3d351d91, which redefined
pg_class.reltuples to be -1 before the first VACUUM or ANALYZE.
Also rename a local variable of the same name ("old_rel_pages"). This is
used by relation truncation to represent the original relation size at
the start of the ongoing VACUUM operation. Rename it to orig_rel_pages,
since that's a lot clearer. (This name matches similar nearby code.)
Most data-corruption reports mention the location of the problem, but
this one failed to. Add it.
Backpatch all the way back. In 12 and older, also assign the
ERRCODE_DATA_CORRUPTED error code as was done in commit fd6ec93bf8 for
13 and later.
Discussion: https://postgr.es/m/202108191637.oqyzrdtnheir@alvherre.pgsql
Somehow, spgist overlooked the need to call pgstat_count_index_scan().
Hence, pg_stat_all_indexes.idx_scan and equivalent columns never
became nonzero for an SP-GiST index, although the related per-tuple
counters worked fine.
This fix works a bit differently from other index AMs, in that the
counter increment occurs in spgrescan not spggettuple/spggetbitmap.
It looks like this won't make the user-visible semantics noticeably
different, so I won't go to the trouble of introducing an is-this-
the-first-call flag just to make the counter bumps happen in the
same places.
Per bug #17163 from Christian Quest. Back-patch to all supported
versions.
Discussion: https://postgr.es/m/17163-b8c5cc88322a5e92@postgresql.org
Adjust track_io_timing related logging code added by commit 94d13d474d.
Make it consistent with other nearby autovacuum and autoanalyze logging
code by removing logic that suppressed zero millisecond outputs.
log_autovacuum_min_duration log output now reliably shows "read:" and
"write:" millisecond-based values in its report (when track_io_timing is
enabled).
Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Stephen Frost <sfrost@snowman.net>
Discussion: https://postgr.es/m/CAH2-WznW0FNxSVQMSRazAMYNfZ6DR_gr5WE78hc6E1CBkkJpzw@mail.gmail.com
Backpatch: 14-, where the track_io_timing logging was introduced.
This order seems more natural. It starts with details that are
particular to heap and index data structures, and ends with system-level
costs incurred during the autovacuum worker's VACUUM/ANALYZE operation.
Author: Peter Geoghegan <pg@bowt.ie>
Discussion: https://postgr.es/m/CAH2-WzkzxK6ahA9xxsOftRtBX_R0swuHZsvo4QUbak1Bz7hb7Q@mail.gmail.com
Backpatch: 14-, which enhanced the log output in various ways.
This was arguably a minor oversight in commit b4af70cb, which cleaned up
the function signatures of functions that modify IndexBulkDeleteResult
variables.
Pengchengliu reported an assertion failure in a parallel woker while
performing a parallel scan using an overflowed snapshot. The proximate
cause is that TransactionXmin was set to an incorrect value. The
underlying cause is incorrect snapshot handling in parallel.c.
In particular, InitializeParallelDSM() was unconditionally calling
GetTransactionSnapshot(), because I (rhaas) mistakenly thought that
was always retrieving an existing snapshot whereas, at isolation
levels less than REPEATABLE READ, it's actually taking a new one. So
instead do this only at higher isolation levels where there actually
is a single snapshot for the whole transaction.
By itself, this is not a sufficient fix, because we still need to
guarantee that TransactionXmin gets set properly in the workers. The
easiest way to do that seems to be to install the leader's active
snapshot as the transaction snapshot if the leader did not serialize a
transaction snapshot. This doesn't affect the results of future
GetTrasnactionSnapshot() calls since those have to take a new snapshot
anyway; what we care about is the side effect of setting TransactionXmin.
Report by Pengchengliu. Patch by Greg Nancarrow, except for some comment
text which I supplied.
Discussion: https://postgr.es/m/002f01d748ac$eaa781a0$bff684e0$@tju.edu.cn
WAL records may span multiple segments, but XLogWrite() does not
wait for the entire record to be written out to disk before
creating archive status files. Instead, as soon as the last WAL page of
the segment is written, the archive status file is created, and the
archiver may process it. If PostgreSQL crashes before it is able to
write and flush the rest of the record (in the next WAL segment), the
wrong version of the first segment file lingers in the archive, which
causes operations such as point-in-time restores to fail.
To fix this, keep track of records that span across segments and ensure
that segments are only marked ready-for-archival once such records have
been completely written to disk.
This has always been wrong, so backpatch all the way back.
Author: Nathan Bossart <bossartn@amazon.com>
Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Reviewed-by: Ryo Matsumura <matsumura.ryo@fujitsu.com>
Reviewed-by: Andrey Borodin <x4mmm@yandex-team.ru>
Discussion: https://postgr.es/m/CBDDFA01-6E40-46BB-9F98-9340F4379505@amazon.com
This reverts the following commits:
1b5617eb84 Describe (auto-)analyze behavior for partitioned tables
0e69f705cc Set pg_class.reltuples for partitioned tables
41badeaba8 Document ANALYZE storage parameters for partitioned tables
0827e8af70 autovacuum: handle analyze for partitioned tables
There are efficiency issues in this code when handling databases with
large numbers of partitions, and it doesn't look like there isn't any
trivial way to handle those. There are some other issues as well. It's
now too late in the cycle for nontrivial fixes, so we'll have to let
Postgres 14 users continue to manually deal with ANALYZE their
partitioned tables, and hopefully we can fix the issues for Postgres 15.
I kept [most of] be280cdad2 ("Don't reset relhasindex for partitioned
tables on ANALYZE") because while we added it due to 0827e8af70, it is
a good bugfix in its own right, since it affects manual analyze as well
as autovacuum-induced analyze, and there's no reason to revert it.
I retained the addition of relkind 'p' to tables included by
pg_stat_user_tables, because reverting that would require a catversion
bump.
Also, in pg14 only, I keep a struct member that was added to
PgStat_TabStatEntry to avoid breaking compatibility with existing stat
files.
Backpatch to 14.
Discussion: https://postgr.es/m/20210722205458.f2bug3z6qzxzpx2s@alap3.anarazel.de
During a VACUUM or CLUSTER command, the initial output emits a
fully qualified relation path with namespace. The post-action
errmsg only emitted the relation name however, which may lead
to hard to parse output when using multiple jobs with vacuumdb
as the output from different jobs may be interleaved. Include
the full path in the post-action errmsg to be consistent with
the initial errmsg.
Author: Mike Fiedler <miketheman@gmail.com>
Reviewed-by: Corey Huinker <corey.huinker@gmail.com>
Discussion: https://postgr.es/m/CAMerE0oz+8G-aORZL_BJcPxnBqewZAvND4bSUysjz+r-oT1BxQ@mail.gmail.com
This commit ensures that the wait interval in the replay delay loop
waiting for an amount of time defined by recovery_min_apply_delay is
correctly handled on reload, recalculating the delay if this GUC value
is updated, based on the timestamp of the commit record being replayed.
The previous behavior would be problematic for example with replay
still waiting even if the delay got reduced or just cancelled. If the
apply delay was increased to a larger value, the wait would have just
respected the old value set, finishing earlier.
Author: Soumyadeep Chakraborty, Ashwin Agrawal
Reviewed-by: Kyotaro Horiguchi, Michael Paquier
Discussion: https://postgr.es/m/CAE-ML+93zfr-HLN8OuxF0BjpWJ17O5dv1eMvSE5jsj9jpnAXZA@mail.gmail.com
Backpatch-through: 9.6
This is a step toward storing stats in dynamic shared memory. As dynamic
shared memory segments are detached from just after before_shmem_exit()
callbacks are processed, but before on_shmem_exit() callbacks are, no stats
can be collected after before_shmem_exit() callbacks have been processed.
Parallel worker shutdown can cause stats to be emitted during DSM detach
callbacks, e.g. for SharedFileSet (which closes its files, which can causes
fd.c to emit stats about temporary files). Therefore parallel worker shutdown
needs to complete during the processing of before_shmem_exit callbacks.
One might think this problem could instead be solved by carefully ordering the
attaching to DSM segments, so that the pgstats segments get detached from
later than the parallel query ones. That turns out to not work because the
stats hash might need to grow which can cause new segments to be
allocated, which then will be detached from earlier.
There are two code changes:
First, call ParallelWorkerShutdown() via before_shmem_exit. That's a good idea
on its own, because other shutdown callbacks like ShutdownPostgres and
ShutdownAuxiliaryProcess are called via before_*.
Second, explicitly detach from the parallel query DSM segment, thereby
ensuring all stats are emitted during ParallelWorkerShutdown().
There are nicer solutions to these problems, but it's not obvious which of
those solutions is the correct one. As the shared memory stats work already is
a huge amount of work...
Author: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/20210405092914.mmxqe7j56lsjfsej@alap3.anarazel.de
Discussion: https://postgr.es/m/20210803023612.iziacxk5syn2r4ut@alap3.anarazel.de
These have been unrelated since bgwriter and checkpointer were split into two
processes in 806a2aee37. As there several pending patches (shared memory
stats, extending the set of tracked IO / buffer statistics) that are made a
bit more awkward by the grouping, split them. Done separately to make
reviewing easier.
This does *not* change the contents of pg_stat_bgwriter or move fields out of
bgwriter/checkpointer stats that arguably do not belong in either. However
pgstat_fetch_global() was renamed and split into
pgstat_fetch_stat_checkpointer() and pgstat_fetch_stat_bgwriter().
Author: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/20210405092914.mmxqe7j56lsjfsej@alap3.anarazel.de
Oversight in commit 3499df0d, which generalized the reloption as a way
of giving users a way to consistently avoid VACUUM's index bypass
optimization.
Per off-list report from Nikolay Shaplov.
Backpatch: 14-, where index cleanup reloption was extended.
Start up the checkpointer and bgwriter during crash recovery (except in
--single mode), as we do for replication. This wasn't done back in
commit cdd46c76 out of caution. Now it seems like a better idea to make
the environment as similar as possible in both cases. There may also be
some performance advantages.
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Reviewed-by: Aleksander Alekseev <aleksander@timescale.com>
Tested-by: Jakub Wartak <Jakub.Wartak@tomtom.com>
Discussion: https://postgr.es/m/CA%2BhUKGJ8NRsqgkZEnsnRc2MFROBV-jCnacbYvtpptK2A9YYp9Q%40mail.gmail.com
They are used in code that runs both during normal operation and during
WAL replay, and needs to behave differently during replay. Move them to
xlogutils.c, because that's where we have other helper functions used by
redo routines.
Reviewed-by: Andres Freund
Discussion: https://www.postgresql.org/message-id/b3b71061-4919-e882-4857-27e370ab134a%40iki.fi
It should always be the case that the last checkpoint record is still
readable, because otherwise, a crash would leave us in a situation
from which we can't recover. Therefore the test removed by this patch
should always succeed. For it to fail, either there has to be a serious
bug in the code someplace, or the user has to be manually modifying
pg_wal while crash recovery is running. If it's the first one, we
should fix the bug. If it's the second one, they should stop, or
anyway they're doing so at their own risk. In neither case does
a full checkpoint instead of an end-of-recovery record seem like a
clear winner. Furthermore, rarely-taken code paths are particularly
vulnerable to bugs, so let's simplify by getting rid of this one.
Discussion: http://postgr.es/m/CA+TgmoYmw==TOJ6EzYb_vcjyS09NkzrVKSyBKUUyo1zBEaJASA@mail.gmail.com
CheckpointLock was removed in commit d18e75664a, and commit ce197e91d0
updated a leftover comment in CreateCheckPoint, but there was another
copy of it in CreateRestartPoint still.
Buildfarm shows that this test has a further failure mode when a
checkpoint starts earlier than expected, so we detect a "checkpoint
completed" line that's not the one we want. Change the config to try
and prevent this.
Per buildfarm
While at it, update one comment that was forgotten in commit
d18e75664a.
Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Discussion: https://postgr.es/m/20210729.162038.534808353849568395.horikyota.ntt@gmail.com
If a file is truncated, we must update minRecoveryPoint. Once a file is
truncated, there's no going back; it would not be safe to stop recovery
at a point earlier than that anymore.
Commit 7bffc9b7bf changed xact_redo_commit() so that it updates
minRecoveryPoint on truncation, but forgot to change xact_redo_abort().
Back-patch to all supported versions.
Reported-by: mengjuan.cmj@alibaba-inc.com
Author: Fujii Masao
Reviewed-by: Heikki Linnakangas
Discussion: https://postgr.es/m/b029fce3-4fac-4265-968e-16f36ff4d075.mengjuan.cmj@alibaba-inc.com
Commit 2c03216d83 changed XLOG_FPI_FOR_HINT records so that they always
included full-page images even when full_page_writes was disabled. However,
in this setting, they don't need to do that because hint bit updates don't
need to be protected from torn writes.
Therefore, this commit makes XLOG_FPI_FOR_HINT records honor full_page_writes
setting. That is, XLOG_FPI_FOR_HINT records may include no full-page images
if full_page_writes is disabled, and WAL replay of them does nothing.
Reported-by: Zhang Wenjie
Author: Kyotaro Horiguchi
Reviewed-by: Fujii Masao
Discussion: https://postgr.es/m/tencent_60F11973A111EED97A8596FFECC4A91ED405@qq.com
When some slots are invalidated due to the max_slot_wal_keep_size limit,
the old segment horizon should move forward to stay within the limit.
However, in commit c655077639 we forgot to call KeepLogSeg again to
recompute the horizon after invalidating replication slots. In cases
where other slots remained, the limits would be recomputed eventually
for other reasons, but if all slots were invalidated, the limits would
not move at all afterwards. Repair.
Backpatch to 13 where the feature was introduced.
Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Reported-by: Marcin Krupowicz <mk@071.ovh>
Discussion: https://postgr.es/m/17103-004130e8f27782c9@postgresql.org
As of v14, pg_depend contains almost 7000 "pin" entries recording
the OIDs of built-in objects. This is a fair amount of bloat for
every database, and it adds time to pg_depend lookups as well as
initdb. We can get rid of all of those entries in favor of an OID
range check, i.e. "OIDs below FirstUnpinnedObjectId are pinned".
(template1 and the public schema are exceptions. Those exceptions
are now wired into IsPinnedObject() instead of initdb's code for
filling pg_depend, but it's the same amount of cruft either way.)
The contents of pg_shdepend are modified likewise.
Discussion: https://postgr.es/m/3737988.1618451008@sss.pgh.pa.us
To add support for streaming transactions at prepare time into the
built-in logical replication, we need to do the following things:
* Modify the output plugin (pgoutput) to implement the new two-phase API
callbacks, by leveraging the extended replication protocol.
* Modify the replication apply worker, to properly handle two-phase
transactions by replaying them on prepare.
* Add a new SUBSCRIPTION option "two_phase" to allow users to enable
two-phase transactions. We enable the two_phase once the initial data sync
is over.
We however must explicitly disable replication of two-phase transactions
during replication slot creation, even if the plugin supports it. We
don't need to replicate the changes accumulated during this phase,
and moreover, we don't have a replication connection open so we don't know
where to send the data anyway.
The streaming option is not allowed with this new two_phase option. This
can be done as a separate patch.
We don't allow to toggle two_phase option of a subscription because it can
lead to an inconsistent replica. For the same reason, we don't allow to
refresh the publication once the two_phase is enabled for a subscription
unless copy_data option is false.
Author: Peter Smith, Ajin Cherian and Amit Kapila based on previous work by Nikhil Sontakke and Stas Kelvich
Reviewed-by: Amit Kapila, Sawada Masahiko, Vignesh C, Dilip Kumar, Takamichi Osumi, Greg Nancarrow
Tested-By: Haiying Tang
Discussion: https://postgr.es/m/02DA5F5E-CECE-4D9C-8B4B-418077E2C010@postgrespro.ru
Discussion: https://postgr.es/m/CAA4eK1+opiV4aFTmWWUF9h_32=HfPOW9vZASHarT0UA5oBrtGw@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 should have been removed in commit 7e30c186da, which split the loop
into two. Only the first loop uses the 'from' variable; updating it in
the second loop is bogus. It was never read after the first loop, so this
was harmless and surely optimized away by the compiler, but let's be tidy.
Backpatch to all supported versions.
Author: Ranier Vilela
Discussion: https://www.postgresql.org/message-id/CAEudQAoWq%2BAL3BnELHu7gms2GN07k-np6yLbukGaxJ1vY-zeiQ%40mail.gmail.com
This concerns pg_stop_backup() and BASE_BACKUP, when waiting for the
WAL segments required for a backup to be archived. This simplifies a
bit the handling of the wait event used in this code path.
Author: Bharath Rupireddy
Reviewed-by: Michael Paquier, Stephen Frost
Discussion: https://postgr.es/m/CALj2ACU4AdPCq6NLfcA-ZGwX7pPCK5FgEj-CAU0xCKzkASSy_A@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
This is reproducible with gcc using at least -O0. The last checks
validating the compression of a block could not be reached with this
variable not set, but let's be clean.
Oversight in 4035cd5, per buildfarm member lapwing.
The logic is implemented so as there can be a choice in the compression
used when building a WAL record, and an extra per-record bit is used to
track down if a block is compressed with PGLZ, LZ4 or nothing.
wal_compression, the existing parameter, is changed to an enum with
support for the following backward-compatible values:
- "off", the default, to not use compression.
- "pglz" or "on", to compress FPWs with PGLZ.
- "lz4", the new mode, to compress FPWs with LZ4.
Benchmarking has showed that LZ4 outclasses easily PGLZ. ZSTD would be
also an interesting choice, but going just with LZ4 for now makes the
patch minimalistic as toast compression is already able to use LZ4, so
there is no need to worry about any build-related needs for this
implementation.
Author: Andrey Borodin, Justin Pryzby
Reviewed-by: Dilip Kumar, Michael Paquier
Discussion: https://postgr.es/m/3037310D-ECB7-4BF1-AF20-01C10BB33A33@yandex-team.ru
The previous commit addressed the chief consequences of a race condition
between InstallXLogFileSegment() and KeepFileRestoredFromArchive(). Fix
three lesser consequences. A spurious durable_rename_excl() LOG message
remained possible. KeepFileRestoredFromArchive() wasted the proceeds of
WAL recycling and preallocation. Finally, XLogFileInitInternal() could
return a descriptor for a file that KeepFileRestoredFromArchive() had
already unlinked. That felt like a recipe for future bugs.
Discussion: https://postgr.es/m/20210202151416.GB3304930@rfd.leadboat.com
Before a restartpoint finishes PreallocXlogFiles(), a startup process
KeepFileRestoredFromArchive() call can unlink the preallocated segment.
If a CHECKPOINT sql command had elicited the restartpoint experiencing
the race condition, that sql command failed. Moreover, the restartpoint
omitted its log_checkpoints message and some inessential resource
reclamation. Prevent the ERROR by skipping open() of the segment.
Since these consequences are so minor, no back-patch.
Discussion: https://postgr.es/m/20210202151416.GB3304930@rfd.leadboat.com
Only initdb used it. initdb refuses to operate on a non-empty directory
and generally does not cope with pre-existing files of other kinds.
Hence, use the opportunity to simplify.
Discussion: https://postgr.es/m/20210202151416.GB3304930@rfd.leadboat.com
Infrequently, the mismatch caused log_checkpoints messages and
TRACE_POSTGRESQL_CHECKPOINT_DONE() to witness an "added" count too high
by one. Since that consequence is so minor, no back-patch.
Discussion: https://postgr.es/m/20210202151416.GB3304930@rfd.leadboat.com
When we cannot immediately acquire XactSLRULock in exclusive mode at
commit time, we add ourselves to a list of processes that need their XIDs
status update. We do this if the clog page where we need to update the
current transaction status is the same as the group leader's clog page,
otherwise, we allow the caller to clear it by itself. Now, when we can't
add ourselves to any group, we were not clearing the current proc if it
has already become a member of some group which was leading to an
assertion failure when the same proc was assigned to another backend after
the current backend exits.
Reported-by: Alexander Lakhin
Bug: 17072
Author: Amit Kapila
Tested-By: Alexander Lakhin
Backpatch-through: 11, where it was introduced
Discussion: https://postgr.es/m/17072-2f8764857ef2c92a@postgresql.org
The failsafe can trigger when index processing is already disabled.
This can happen when VACUUM's INDEX_CLEANUP parameter is "off" and the
failsafe happens to trigger. Remove assertions that assume that index
processing is directly tied to the failsafe.
Oversight in commit c242baa4, which made it possible for the failsafe to
trigger in a two-pass strategy VACUUM that has yet to make its first
call to lazy_vacuum_all_indexes().
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
One of the error paths left *members uninitialized. That's not a live
bug, because most callers don't look at *members when the function
returns -1, but let's be tidy. One caller, in heap_lock_tuple(), does
"if (members != NULL) pfree(members)", but AFAICS it never passes an
invalid 'multi' value so it should not reach that error case.
The callers are also a bit inconsistent in their expectations.
heap_lock_tuple() pfrees the 'members' array if it's not-NULL, others
pfree() it if "nmembers >= 0", and others if "nmembers > 0". That's
not a live bug either, because the function should never return 0, but
add an Assert for that to make it more clear. I left the callers alone
for now.
I also moved the line where we set *nmembers. It wasn't wrong before,
but I like to do that right next to the 'return' statement, to make it
clear that it's always set on return.
Also remove one unreachable return statement after ereport(ERROR), for
brevity and for consistency with the similar if-block right after it.
Author: Greg Nancarrow with the additional changes by me
Backpatch-through: 9.6, all supported versions
Since commit c24dcd0cfd, we have been using pg_pread() to read the WAL
file, which doesn't change the seek position (unless we fall back to
the implementation in src/port/pread.c). Update comment accordingly.
Backpatch-through: 12, where we started to use pg_pread()
Bugfix commit 5fc89376 effectively made the lock_waiter_detected field
from vacuumlazy.c's global state struct into private state owned by
lazy_truncate_heap(). Finish this off by replacing the struct field
with a local variable.
The extra checks added by the recompression of toast data introduced in
bbe0a81 is proving to have a performance impact on VACUUM or CLUSTER
even if no recompression is done. This is more noticeable with more
toastable columns that contain non-NULL values.
Improvements could be done to make those extra checks less expensive,
but that's not material for 14 at this stage, and we are not sure either
if the code path of VACUUM FULL/CLUSTER is adapted for this job.
Per discussion with several people, including Andres Freund, Robert
Haas, Álvaro Herrera, Tom Lane and myself.
Discussion: https://postgr.es/m/20210527003144.xxqppojoiwurc2iz@alap3.anarazel.de
We were already reporting it, but only after the parallel workers were
finished, which is visibly much later than what happens in a serial
build.
With this change we report it when the leader starts its own sort phase
when participating in the build (the normal case). Now this might
happen a little later than when the workers start their sorting phases,
but a) communicating the actual phase start from workers is likely to be
a hassle, and b) the sort phase start is pretty fuzzy anyway, since
sorting per se is actually initiated by tuplesort.c internally earlier
than tuplesort_performsort() is called.
Backpatch to pg12, where the progress reporting code for CREATE INDEX
went in.
Reported-by: Tomas Vondra <tomas.vondra@enterprisedb.com>
Author: Matthias van de Meent <boekewurm+postgres@gmail.com>
Reviewed-by: Greg Nancarrow <gregn4422@gmail.com>
Reviewed-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/1128176d-1eee-55d4-37ca-e63644422adb
This only happens if (1) the new standby has no WAL available locally,
(2) the new standby is starting from the old timeline, (3) the promotion
happened in the WAL segment from which the new standby is starting,
(4) the timeline history file for the new timeline is available from
the archive but the WAL files for are not (i.e. this is a race),
(5) the WAL files for the new timeline are available via streaming,
and (6) recovery_target_timeline='latest'.
Commit ee994272ca introduced this
logic and was an improvement over the previous code, but it mishandled
this case. If recovery_target_timeline='latest' and restore_command is
set, validateRecoveryParameters() can change recoveryTargetTLI to be
different from receiveTLI. If streaming is then tried afterward,
expectedTLEs gets initialized with the history of the wrong timeline.
It's supposed to be a list of entries explaining how to get to the
target timeline, but in this case it ends up with a list of entries
explaining how to get to the new standby's original timeline, which
isn't right.
Dilip Kumar and Robert Haas, reviewed by Kyotaro Horiguchi.
Discussion: http://postgr.es/m/CAFiTN-sE-jr=LB8jQuxeqikd-Ux+jHiXyh4YDiZMPedgQKup0g@mail.gmail.com
This tidies up some questionable coding which made use of
DatumGetPointer() for Datums being passed into functions where the
parameter is expected to be a cstring. We saw no compiler warnings with
the old code as the Pointer type used in DatumGetPointer() happens to
be a char * rather than a void *. However, that's no excuse and we should
be using the correct macro for the job.
Here we also make use of OutputFunctionCall() rather than using
FunctionCall1() directly to call the type's output function.
OutputFunctionCall() is the standard way to do this. It casts the
returned value to a cstring for us.
In passing get rid of a duplicate call to strlen(). Most compilers will
likely optimize away the 2nd call, but there may be some that won't. In
any case, this just aligns the code to some other nearby code that already
does this.
Discussion: https://postgr.es/m/CAApHDvq1D=ehZ8hey8Hz67N+_Zth0GHO5wiVCfv1YcGPMXJq0A@mail.gmail.com
Fix a few places that were using appendStringInfo() when they should have
been using appendStringInfoString(). Also some cases of
appendPQExpBuffer() that would have been better suited to use
appendPQExpBufferChar(), and finally, some places that used
appendPQExpBuffer() when appendPQExpBufferStr() would have suited better.
There are no bugs are being fixed here. The aim is just to make the code
use the most optimal function for the job.
All the code being changed here is new to PG14. It makes sense to fix
these before we branch for PG15. There are a few other places that we
could fix, but those cases are older code so fixing those seems less
worthwhile as it may cause unnecessary back-patching pain in the future.
Author: Hou Zhijie
Discussion: https://postgr.es/m/OS0PR01MB5716732158B1C4142C6FE375943D9@OS0PR01MB5716.jpnprd01.prod.outlook.com
Redefine '\0' (InvalidCompressionMethod) as meaning "if we need to
compress, use the current setting of default_toast_compression".
This allows '\0' to be a suitable default choice regardless of
datatype, greatly simplifying code paths that initialize tupledescs
and the like. It seems like a more user-friendly approach as well,
because now the default compression choice doesn't migrate into table
definitions, meaning that changing default_toast_compression is
usually sufficient to flip an installation's behavior; one needn't
tediously issue per-column ALTER SET COMPRESSION commands.
Along the way, fix a few minor bugs and documentation issues
with the per-column-compression feature. Adopt more robust
APIs for SetIndexStorageProperties and GetAttributeCompression.
Bump catversion because typical contents of attcompression will now
be different. We could get away without doing that, but it seems
better to ensure v14 installations all agree on this. (We already
forced initdb for beta2, anyway.)
Discussion: https://postgr.es/m/626613.1621787110@sss.pgh.pa.us
VACUUM FULL and CLUSTER can be used to enforce the use of the existing
compression method of a toastable column if a value currently stored is
compressed with a method that does not match the column's defined
method. The code in charge of decompressing and recompressing toast
values at rewrite left around the detoasted values, causing an
accumulation of memory allocated in TopTransactionContext.
When processing large relations, this could cause the system to run out
of memory. The detoasted values are not needed once their tuple is
rewritten, and this commit ensures that the necessary cleanup happens.
Issue introduced by bbe0a81d. The comments of the area are reordered a
bit while on it.
Reported-by: Andres Freund
Analyzed-by: Andres Freund
Author: Michael Paquier
Reviewed-by: Dilip Kumar
Discussion: https://postgr.es/m/20210521211929.pcehg6f23icwstdb@alap3.anarazel.de
The wraparound failsafe mechanism added by commit 1e55e7d1 handled the
one-pass strategy case (i.e. the "table has no indexes" case) by adding
a dedicated failsafe check. This made up for the fact that the usual
one-pass checks inside lazy_vacuum_all_indexes() cannot ever be reached
during a one-pass strategy VACUUM.
This approach failed to account for two-pass VACUUMs that opt out of
index vacuuming up-front. The INDEX_CLEANUP off case in the only case
that works like that.
Fix this by performing a failsafe check every 4GB during the first scan
of the heap, regardless of the details of the VACUUM. This eliminates
the special case, and will make the failsafe trigger more reliably.
Author: Peter Geoghegan <pg@bowt.ie>
Reported-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Masahiko Sawada <sawada.mshk@gmail.com>
Discussion: https://postgr.es/m/20210424002921.pb3t7h6frupdqnkp@alap3.anarazel.de
Now that attcompression is just a char, there's a lot of wasted
padding space after it. Move it into the group of char-wide
columns to save a net of 4 bytes per pg_attribute entry. While
we're at it, swap the order of attstorage and attalign to make for
a more logical grouping of these columns.
Also re-order actions in related code to match the new field ordering.
This patch also fixes one outright bug: equalTupleDescs() failed to
compare attcompression. That could, for example, cause relcache
reload to fail to adopt a new value following a change.
Michael Paquier and Tom Lane, per a gripe from Andres Freund.
Discussion: https://postgr.es/m/20210517204803.iyk5wwvwgtjcmc5w@alap3.anarazel.de
exec_for_query() normally tries to prefetch a few rows at a time
from the query being iterated over, so as to reduce executor
entry/exit overhead. Unfortunately this is unsafe if we have
COMMIT or ROLLBACK within the loop, because there might be
TOAST references in the data that we prefetched but haven't
yet examined. Immediately after the COMMIT/ROLLBACK, we have
no snapshots in the session, meaning that VACUUM is at liberty
to remove recently-deleted TOAST rows.
This was originally reported as a case triggering the "no known
snapshots" error in init_toast_snapshot(), but even if you miss
hitting that, you can get "missing toast chunk", as illustrated
by the added isolation test case.
To fix, just disable prefetching in non-atomic contexts. Maybe
there will be performance complaints prompting us to work harder
later, but it's not clear at the moment that this really costs
much, and I doubt we'd want to back-patch any complicated fix.
In passing, adjust that error message in init_toast_snapshot()
to be a little clearer about the likely cause of the problem.
Patch by me, based on earlier investigation by Konstantin Knizhnik.
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
If a promotion is triggered while recovery is paused, the paused state ends
and promotion continues. But previously in that case
pg_get_wal_replay_pause_state() returned 'paused' wrongly while a promotion
was ongoing.
This commit changes a standby promotion so that it marks the recovery
pause state as 'not paused' when it's triggered, to fix the issue.
Author: Fujii Masao
Reviewed-by: Dilip Kumar, Kyotaro Horiguchi
Discussion: https://postgr.es/m/f706876c-4894-0ba5-6f4d-79803eeea21b@oss.nttdata.com
Add a defensive "can't happen" error to code that handles nbtree posting
list splits (promote an existing assertion). This avoids a segfault in
the event of an insertion of a newitem that is somehow identical to an
existing non-pivot tuple in the index. An nbtree index should never
have two index tuples with identical TIDs.
This scenario is not particular unlikely in the event of any kind of
corruption that leaves the index in an inconsistent state relative to
the heap relation that is indexed. There are two known reports of
preventable hard crashes. Doing nothing seems unacceptable given the
general expectation that nbtree will cope reasonably well with corrupt
data.
Discussion: https://postgr.es/m/CAH2-Wz=Jr_d-dOYEEmwz0-ifojVNWho01eAqewfQXgKfoe114w@mail.gmail.com
Backpatch: 13-, where nbtree deduplication was introduced.
Formerly we just relied on operator classes that assert longValuesOK
to eventually shorten the leaf value enough to fit on an index page.
That fails since the introduction of INCLUDE-column support (commit
09c1c6ab4), because the INCLUDE columns might alone take up more
than a page, meaning no amount of leaf-datum compaction will get
the job done. At least with spgtextproc.c, that leads to an infinite
loop, since spgtextproc.c won't throw an error for not being able
to shorten the leaf datum anymore.
To fix without breaking cases that would otherwise work, add logic
to spgdoinsert() to verify that the leaf tuple size is decreasing
after each "choose" step. Some opclasses might not decrease the
size on every single cycle, and in any case, alignment roundoff
of the tuple size could obscure small gains. Therefore, allow
up to 10 cycles without additional savings before throwing an
error. (Perhaps this number will need adjustment, but it seems
quite generous right now.)
As long as we've developed this logic, let's back-patch it.
The back branches don't have INCLUDE columns to worry about, but
this seems like a good defense against possible bugs in operator
classes. We already know that an infinite loop here is pretty
unpleasant, so having a defense seems to outweigh the risk of
breaking things. (Note that spgtextproc.c is actually the only
known opclass with longValuesOK support, so that this is all moot
for known non-core opclasses anyway.)
Per report from Dilip Kumar.
Discussion: https://postgr.es/m/CAFiTN-uxP_soPhVG840tRMQTBmtA_f_Y8N51G7DKYYqDh7XN-A@mail.gmail.com
Knowing that a buggy opclass could cause an infinite insertion loop,
spgdoinsert() intended to allow its loop to be interrupted by query
cancel. However, that never actually worked, because in iterations
after the first, we'd be holding buffer lock(s) which would cause
InterruptHoldoffCount to be positive, preventing servicing of the
interrupt.
To fix, check if an interrupt is pending, and if so fall out of
the insertion loop and service the interrupt after we've released
the buffers. If it was indeed a query cancel, that's the end of
the matter. If it was a non-canceling interrupt reason, make use
of the existing provision to retry the whole insertion. (This isn't
as wasteful as it might seem, since any upper-level index tuples we
already created should be usable in the next attempt.)
While there's no known instance of such a bug in existing release
branches, it still seems like a good idea to back-patch this to
all supported branches, since the behavior is fairly nasty if a
loop does happen --- not only is it uncancelable, but it will
quickly consume memory to the point of an OOM failure. In any
case, this code is certainly not working as intended.
Per report from Dilip Kumar.
Discussion: https://postgr.es/m/CAFiTN-uxP_soPhVG840tRMQTBmtA_f_Y8N51G7DKYYqDh7XN-A@mail.gmail.com
The percentage of blocks from the table value reported by autovacuum log
output (following commit 5100010ee4) should never exceed 100% because
it describes the state of the table back when lazy_vacuum() was called.
The value could nevertheless exceed 100% in the event of heap relation
truncation. We failed to compensate for how truncation affects
rel_pages.
Fix the faulty accounting by using the original rel_pages value instead
of the current/final rel_pages value.
Reported-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/20210423204306.5osfpkt2ggaedyvy@alap3.anarazel.de
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.
Previously long was used as the data type for some counters in BufferUsage
and WalUsage. But long is only four byte, e.g., on Windows, and it's entirely
possible to wrap a four byte counter. For example, emitting more than
four billion WAL records in one transaction isn't actually particularly rare.
To avoid the overflows of those counters, this commit changes the data type
of them from long to int64.
Suggested-by: Andres Freund
Author: Masahiro Ikeda
Reviewed-by: Fujii Masao
Discussion: https://postgr.es/m/20201221211650.k7b53tcnadrciqjo@alap3.anarazel.de
Discussion: https://postgr.es/m/af0964ac-7080-1984-dc23-513754987716@oss.nttdata.com
It's unusual to have any resjunk columns in an ON CONFLICT ... UPDATE
list, but it can happen when MULTIEXPR_SUBLINK SubPlans are present.
If it happens, the ON CONFLICT UPDATE code path would end up storing
tuples that include the values of the extra resjunk columns. That's
fairly harmless in the short run, but if new columns are added to
the table then the values would become accessible, possibly leading
to malfunctions if they don't match the datatypes of the new columns.
This had escaped notice through a confluence of missing sanity checks,
including
* There's no cross-check that a tuple presented to heap_insert or
heap_update matches the table rowtype. While it's difficult to
check that fully at reasonable cost, we can easily add assertions
that there aren't too many columns.
* The output-column-assignment cases in execExprInterp.c lacked
any sanity checks on the output column numbers, which seems like
an oversight considering there are plenty of assertion checks on
input column numbers. Add assertions there too.
* We failed to apply nodeModifyTable's ExecCheckPlanOutput() to
the ON CONFLICT UPDATE tlist. That wouldn't have caught this
specific error, since that function is chartered to ignore resjunk
columns; but it sure seems like a bad omission now that we've seen
this bug.
In HEAD, the right way to fix this is to make the processing of
ON CONFLICT UPDATE tlists work the same as regular UPDATE tlists
now do, that is don't add "SET x = x" entries, and use
ExecBuildUpdateProjection to evaluate the tlist and combine it with
old values of the not-set columns. This adds a little complication
to ExecBuildUpdateProjection, but allows removal of a comparable
amount of now-dead code from the planner.
In the back branches, the most expedient solution seems to be to
(a) use an output slot for the ON CONFLICT UPDATE projection that
actually matches the target table, and then (b) invent a variant of
ExecBuildProjectionInfo that can be told to not store values resulting
from resjunk columns, so it doesn't try to store into nonexistent
columns of the output slot. (We can't simply ignore the resjunk columns
altogether; they have to be evaluated for MULTIEXPR_SUBLINK to work.)
This works back to v10. In 9.6, projections work much differently and
we can't cheaply give them such an option. The 9.6 version of this
patch works by inserting a JunkFilter when it's necessary to get rid
of resjunk columns.
In addition, v11 and up have the reverse problem when trying to
perform ON CONFLICT UPDATE on a partitioned table. Through a
further oversight, adjust_partition_tlist() discarded resjunk columns
when re-ordering the ON CONFLICT UPDATE tlist to match a partition.
This accidentally prevented the storing-bogus-tuples problem, but
at the cost that MULTIEXPR_SUBLINK cases didn't work, typically
crashing if more than one row has to be updated. Fix by preserving
resjunk columns in that routine. (I failed to resist the temptation
to add more assertions there too, and to do some minor code
beautification.)
Per report from Andres Freund. Back-patch to all supported branches.
Security: CVE-2021-32028
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
The all_visible_according_to_vm variable's value is inherently prone to
becoming invalidated concurrently, since it is set before we even
acquire a lock on a related heap page buffer.
Oversight in commit 7136bf34, which added the assertion in passing.
Author: Masahiko Sawada <sawada.mshk@gmail.com>
Reported-By: Tang <tanghy.fnst@fujitsu.com>
Diagnosed-By:: Masahiko Sawada <sawada.mshk@gmail.com>
Discussion: https://postgr.es/m/CAD21AoDzgc8_MYrA5m1fyydomw_eVKtQiYh7sfDK4KEhdMsf_g@mail.gmail.com
6f6f284 has introduced a specific macro to make printf()-ing of LSNs
easier. This takes care of what looks like the remaining code paths
that did not get the call.
Author: Michael Paquier
Reviewed-by: Kyotaro Horiguchi, Tom Lane
Discussion: https://postgr.es/m/YIJS9x6K8ruizN7j@paquier.xyz
While tracking down the bug fixed in the preceding commit, I got quite
annoyed by the low quality of spg_desc's output. Add missing fields,
try to make the formatting consistent.
Document VACUUM's soft assumption that any LP_DEAD items encountered
during pruning will become LP_UNUSED items before VACUUM finishes up.
This is integral to the accounting used by VACUUM to generate its final
report on the table to the stats collector. It also affects how VACUUM
determines which heap pages are truncatable. In both cases VACUUM is
concerned with the likely contents of the page in the near future, not
the current contents of the page.
This state of affairs created the false impression that VACUUM's dead
tuple accounting had significant difference with similar accounting used
during ANALYZE. There were and are no substantive differences, at least
when the soft assumption completely works out. This is far clearer now.
Also document cases where things don't quite work out for VACUUM's dead
tuple accounting. It's possible that a significant number of LP_DEAD
items will be left behind by VACUUM, and won't be recorded as remaining
dead tuples in VACUUM's statistics collector report. This behavior
dates back to commit a96c41fe, which taught VACUUM to run without index
and heap vacuuming at the user's request. The failsafe mechanism added
to VACUUM more recently by commit 1e55e7d1 takes the same approach to
dead tuple accounting.
Reported-By: Masahiko Sawada <sawada.mshk@gmail.com>
Discussion: https://postgr.es/m/CAH2-Wz=Jmtu18PrsYq3EvvZJGOmZqSO2u3bvKpx9xJa5uhNp=Q@mail.gmail.com
It seems like a good idea to bypass heap truncation when the wraparound
failsafe mechanism (which was added in commit 1e55e7d1) is in effect.
Deliberately don't bypass heap truncation in the INDEX_CLEANUP=off case,
even though it is similar to the failsafe case. There is already a
separate reloption (and related VACUUM parameter) for that.
Reported-By: Masahiko Sawada <sawada.mshk@gmail.com>
Discussion: https://postgr.es/m/CAD21AoDWRh6oTN5T8wa+cpZUVpHXET8BJ8Da7WHVHpwkPP6KLg@mail.gmail.com
heap_update needs to clear any existing "all visible" flag on
the old tuple's page (and on the new page too, if different).
Per coding rules, to do this it must acquire pin on the appropriate
visibility-map page while not holding exclusive buffer lock;
which creates a race condition since someone else could set the
flag whenever we're not holding the buffer lock. The code is
supposed to handle that by re-checking the flag after acquiring
buffer lock and retrying if it became set. However, one code
path through heap_update itself, as well as one in its subroutine
RelationGetBufferForTuple, failed to do this. The end result,
in the unlikely event that a concurrent VACUUM did set the flag
while we're transiently not holding lock, is a non-recurring
"PANIC: wrong buffer passed to visibilitymap_clear" failure.
This has been seen a few times in the buildfarm since recent VACUUM
changes that added code paths that could set the all-visible flag
while holding only exclusive buffer lock. Previously, the flag
was (usually?) set only after doing LockBufferForCleanup, which
would insist on buffer pin count zero, thus preventing the flag
from becoming set partway through heap_update. However, it's
clear that it's heap_update not VACUUM that's at fault here.
What's less clear is whether there is any hazard from these bugs
in released branches. heap_update is certainly violating API
expectations, but if there is no code path that can set all-visible
without a cleanup lock then it's only a latent bug. That's not
100% certain though, besides which we should worry about extensions
or future back-patch fixes that could introduce such code paths.
I chose to back-patch to v12. Fixing RelationGetBufferForTuple
before that would require also back-patching portions of older
fixes (notably 0d1fe9f74), which is more code churn than seems
prudent to fix a hypothetical issue.
Discussion: https://postgr.es/m/2247102.1618008027@sss.pgh.pa.us
Commit 6f38d4dac3 failed to heed a warning about the stability of the
value pointed to by "otid". The caller is allowed to pass in a pointer to
newtup->t_self, which will be updated during the execution of the
function. Instead, the SSI check should use the value we copy into
oldtup.t_self near the top of the function.
Not a live bug, because newtup->t_self doesn't really get updated until
a bit later, but it was confusing and broke the rule established by the
comment.
Back-patch to 13.
Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/2689164.1618160085%40sss.pgh.pa.us
Commit 438fc4a39c prevented the WAL replay from writing
COMMIT_TS_SETTS record. By this change there is no code that
generates COMMIT_TS_SETTS record in PostgreSQL core.
Also we can think that there are no extensions using the record
because we've not received so far any complaints about the issue
that commit 438fc4a39c fixed. Therefore this commit removes
COMMIT_TS_SETTS record and its related code. Even without
this record, the timestamp required for commit timestamp feature
can be acquired from the COMMIT record.
Bump WAL page magic.
Reported-by: lx zou <zoulx1982@163.com>
Author: Fujii Masao
Reviewed-by: Alvaro Herrera
Discussion: https://postgr.es/m/16931-620d0f2fdc6108f1@postgresql.org
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
Teach xlogreader.c to decode its output into a circular buffer, to
support optimizations based on looking ahead.
* XLogReadRecord() works as before, consuming records one by one, and
allowing them to be examined via the traditional XLogRecGetXXX()
macros.
* An alternative new interface XLogNextRecord() is added that returns
pointers to DecodedXLogRecord structs that can be examined directly.
* XLogReadAhead() provides a second cursor that lets you see
further ahead, as long as data is available and there is enough space
in the decoding buffer. This returns DecodedXLogRecord pointers to the
caller, but also adds them to a queue of records that will later be
consumed by XLogNextRecord()/XLogReadRecord().
The buffer's size is controlled with wal_decode_buffer_size. The buffer
could potentially be placed into shared memory, for future projects.
Large records that don't fit in the circular buffer are called
"oversized" and allocated separately with palloc().
Discussion: https://postgr.es/m/CA+hUKGJ4VJN8ttxScUFM8dOKX0BrBiboo5uz1cq=AovOddfHpA@mail.gmail.com
Previously, the XLogReader module would fetch new input data using a
callback function. Redesign the interface so that it tells the caller
to insert more data with a special return value instead. This API suits
later patches for prefetching, encryption and maybe other future
projects that would otherwise require continually extending the callback
interface.
As incidental cleanup work, move global variables readOff, readLen and
readSegNo inside XlogReaderState.
Author: Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>
Author: Heikki Linnakangas <hlinnaka@iki.fi> (parts of earlier version)
Reviewed-by: Antonin Houska <ah@cybertec.at>
Reviewed-by: Alvaro Herrera <alvherre@2ndquadrant.com>
Reviewed-by: Takashi Menjo <takashi.menjo@gmail.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Thomas Munro <thomas.munro@gmail.com>
Discussion: https://postgr.es/m/20190418.210257.43726183.horiguchi.kyotaro%40lab.ntt.co.jp
Previously, autovacuum would completely ignore partitioned tables, which
is not good regarding analyze -- failing to analyze those tables means
poor plans may be chosen. Make autovacuum aware of those tables by
propagating "changes since analyze" counts from the leaf partitions up
the partitioning hierarchy.
This also introduces necessary reloptions support for partitioned tables
(autovacuum_enabled, autovacuum_analyze_scale_factor,
autovacuum_analyze_threshold). It's unclear how best to document this
aspect.
Author: Yuzuko Hosoya <yuzukohosoya@gmail.com>
Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Reviewed-by: Tomas Vondra <tomas.vondra@enterprisedb.com>
Reviewed-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/CAKkQ508_PwVgwJyBY=0Lmkz90j8CmWNPUxgHvCUwGhMrouz6UA@mail.gmail.com
VACUUM has never needed to call ambulkdelete() for each index in cases
where there are precisely zero TIDs in its dead_tuples array by the end
of its first pass over the heap (also its only pass over the heap in
this scenario). Index vacuuming is simply not required when this
happens. Index cleanup will still go ahead, but in practice most calls
to amvacuumcleanup() are usually no-ops when there were zero preceding
ambulkdelete() calls. In short, VACUUM has generally managed to avoid
index scans when there were clearly no index tuples to delete from
indexes. But cases with _close to_ no index tuples to delete were
another matter -- a round of ambulkdelete() calls took place (one per
index), each of which performed a full index scan.
VACUUM now behaves just as if there were zero index tuples to delete in
cases where there are in fact "virtually zero" such tuples. That is, it
can now bypass index vacuuming and heap vacuuming as an optimization
(though not index cleanup). Whether or not VACUUM bypasses indexes is
determined dynamically, based on the just-observed number of heap pages
in the table that have one or more LP_DEAD items (LP_DEAD items in heap
pages have a 1:1 correspondence with index tuples that still need to be
deleted from each index in the worst case).
We only skip index vacuuming when 2% or less of the table's pages have
one or more LP_DEAD items -- bypassing index vacuuming as an
optimization must not noticeably impede setting bits in the visibility
map. As a further condition, the dead_tuples array (i.e. VACUUM's array
of LP_DEAD item TIDs) must not exceed 32MB at the point that the first
pass over the heap finishes, which is also when the decision to bypass
is made. (The VACUUM must also have been able to fit all TIDs in its
maintenance_work_mem-bound dead_tuples space, though with a default
maintenance_work_mem setting it can't matter.)
This avoids surprising jumps in the duration and overhead of routine
vacuuming with workloads where successive VACUUM operations consistently
have almost zero dead index tuples. The number of LP_DEAD items may
well accumulate over multiple VACUUM operations, before finally the
threshold is crossed and VACUUM performs conventional index vacuuming.
Even then, the optimization will have avoided a great deal of largely
unnecessary index vacuuming.
In the future we may teach VACUUM to skip index vacuuming on a per-index
basis, using a much more sophisticated approach. For now we only
consider the extreme cases, where we can be quite confident that index
vacuuming just isn't worth it using simple heuristics.
Also log information about how many heap pages have one or more LP_DEAD
items when autovacuum logging is enabled.
Author: Masahiko Sawada <sawada.mshk@gmail.com>
Author: Peter Geoghegan <pg@bowt.ie>
Discussion: https://postgr.es/m/CAD21AoD0SkE11fMw4jD4RENAwBMcw1wasVnwpJVw3tVqPOQgAw@mail.gmail.com
Discussion: https://postgr.es/m/CAH2-WzmkebqPd4MVGuPTOS9bMFvp9MDs5cRTCOsv1rQJ3jCbXw@mail.gmail.com
Add a failsafe mechanism that is triggered by VACUUM when it notices
that the table's relfrozenxid and/or relminmxid are dangerously far in
the past. VACUUM checks the age of the table dynamically, at regular
intervals.
When the failsafe triggers, VACUUM takes extraordinary measures to
finish as quickly as possible so that relfrozenxid and/or relminmxid can
be advanced. VACUUM will stop applying any cost-based delay that may be
in effect. VACUUM will also bypass any further index vacuuming and heap
vacuuming -- it only completes whatever remaining pruning and freezing
is required. Bypassing index/heap vacuuming is enabled by commit
8523492d, which made it possible to dynamically trigger the mechanism
already used within VACUUM when it is run with INDEX_CLEANUP off.
It is expected that the failsafe will almost always trigger within an
autovacuum to prevent wraparound, long after the autovacuum began.
However, the failsafe mechanism can trigger in any VACUUM operation.
Even in a non-aggressive VACUUM, where we're likely to not advance
relfrozenxid, it still seems like a good idea to finish off remaining
pruning and freezing. An aggressive/anti-wraparound VACUUM will be
launched immediately afterwards. Note that the anti-wraparound VACUUM
that follows will itself trigger the failsafe, usually before it even
begins its first (and only) pass over the heap.
The failsafe is controlled by two new GUCs: vacuum_failsafe_age, and
vacuum_multixact_failsafe_age. There are no equivalent reloptions,
since that isn't expected to be useful. The GUCs have rather high
defaults (both default to 1.6 billion), and are expected to generally
only be used to make the failsafe trigger sooner/more frequently.
Author: Masahiko Sawada <sawada.mshk@gmail.com>
Author: Peter Geoghegan <pg@bowt.ie>
Discussion: https://postgr.es/m/CAD21AoD0SkE11fMw4jD4RENAwBMcw1wasVnwpJVw3tVqPOQgAw@mail.gmail.com
Discussion: https://postgr.es/m/CAH2-WzmgH3ySGYeC-m-eOBsa2=sDwa292-CFghV4rESYo39FsQ@mail.gmail.com
Teach VACUUM to truncate the line pointer array of each heap page when a
contiguous group of LP_UNUSED line pointers appear at the end of the
array -- these unused and unreferenced items are excluded. This process
occurs during VACUUM's second pass over the heap, right after LP_DEAD
line pointers on the page (those encountered/pruned during the first
pass) are marked LP_UNUSED.
Truncation avoids line pointer bloat with certain workloads,
particularly those involving continual range DELETEs and bulk INSERTs
against the same table.
Also harden heapam code to check for an out-of-range page offset number
in places where we weren't already doing so.
Author: Matthias van de Meent <boekewurm+postgres@gmail.com>
Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Masahiko Sawada <sawada.mshk@gmail.com>
Reviewed-By: Peter Geoghegan <pg@bowt.ie>
Discussion: https://postgr.es/m/CAEze2WjgaQc55Y5f5CQd3L=eS5CZcff2Obxp=O6pto8-f0hC4w@mail.gmail.com
Discussion: https://postgr.es/m/CAH2-Wzn6a64PJM1Ggzm=uvx2otsopJMhFQj_g1rAj4GWr3ZSzw@mail.gmail.com
The code in bringetbitmap() simply added the whole matching page range
to the TID bitmap, as determined by pages_per_range, even if some of the
pages were beyond the end of the heap. The query then might fail with
an error like this:
ERROR: could not open file "base/20176/20228.2" (target block
262144): previous segment is only 131021 blocks
In this case, the relation has 262093 pages (131072 and 131021 pages),
but we're trying to acess block 262144, i.e. first block of the 3rd
segment. At that point _mdfd_getseg() notices the preceding segment is
incomplete, and fails.
Hitting this in practice is rather unlikely, because:
* Most indexes use power-of-two ranges, so segments and page ranges
align perfectly (segment end is also a page range end).
* The table size has to be just right, with the last segment being
almost full - less than one page range from full segment, so that the
last page range actually crosses the segment boundary.
* Prefetch has to be enabled. The regular page access checks that
pages are not beyond heap end, but prefetch does not. On older
releases (before 12) the execution stops after hitting the first
non-existent page, so the prefetch distance has to be sufficient
to reach the first page in the next segment to trigger the issue.
Since 12 it's enough to just have prefetch enabled, the prefetch
distance does not matter.
Fixed by not adding non-existent pages to the TID bitmap. Backpatch
all the way back to 9.6 (BRIN indexes were introduced in 9.5, but that
release is EOL).
Backpatch-through: 9.6
This reverts commit 9f984ba6d2.
It was making the buildfarm unhappy, apparently setting client_min_messages
in a regression test produces different output if log_statement='all'.
Another issue is that I now suspect the bit sortsupport function was in
fact not correct to call byteacmp(). Revert to investigate both of those
issues.
Bloom, GIN, GiST and SP-GiST rely on PageInit() to initialize the
contents of a page, and this routine fills entirely a page with zeros
for a size of BLCKSZ, including the special space. Those index AMs have
been using an extra memset() call to fill with zeros the special page
space, or even the whole page, which is not necessary as PageInit()
already does this work, so let's remove them. GiST was not doing this
extra call, but has commented out a system call that did so since
6236991.
While on it, remove one MAXALIGN() for SP-GiST as PageInit() takes care
of that. This makes the whole page initialization logic more consistent
across all index AMs.
Author: Bharath Rupireddy
Reviewed-by: Vignesh C, Mahendra Singh Thalor
Discussion: https://postgr.es/m/CALj2ACViOo2qyaPT7krWm4LRyRTw9kOXt+g6PfNmYuGA=YHj9A@mail.gmail.com
Retry the call to heap_prune_page() in rare cases where there is
disagreement between the heap_prune_page() call and the call to
HeapTupleSatisfiesVacuum() that immediately follows. Disagreement is
possible when a concurrently-aborted transaction makes a tuple DEAD
during the tiny window between each step. This was the only case where
a tuple considered DEAD by VACUUM still had storage following pruning.
VACUUM's definition of dead tuples is now uniformly simple and
unambiguous: dead tuples from each page are always LP_DEAD line pointers
that were encountered just after we performed pruning (and just before
we considered freezing remaining items with tuple storage).
Eliminating the tupgone=true special case enables INDEX_CLEANUP=off
style skipping of index vacuuming that takes place based on flexible,
dynamic criteria. The INDEX_CLEANUP=off case had to know about skipping
indexes up-front before now, due to a subtle interaction with the
special case (see commit dd695979) -- this was a special case unto
itself. Now there are no special cases. And so now it won't matter
when or how we decide to skip index vacuuming: it won't affect how
pruning behaves, and it won't be affected by any of the implementation
details of pruning or freezing.
Also remove XLOG_HEAP2_CLEANUP_INFO records. These are no longer
necessary because we now rely entirely on heap pruning taking care of
recovery conflicts. There is no longer any need to generate recovery
conflicts for DEAD tuples that pruning just missed. This also means
that heap vacuuming now uses exactly the same strategy for recovery
conflicts as index vacuuming always has: REDO routines never need to
process a latestRemovedXid from the WAL record, since earlier REDO of
the WAL record from pruning is sufficient in all cases. The generic
XLOG_HEAP2_CLEAN record type is now split into two new record types to
reflect this new division (these are called XLOG_HEAP2_PRUNE and
XLOG_HEAP2_VACUUM).
Also stop acquiring a super-exclusive lock for heap pages when they're
vacuumed during VACUUM's second heap pass. A regular exclusive lock is
enough. This is correct because heap page vacuuming is now strictly a
matter of setting the LP_DEAD line pointers to LP_UNUSED. No other
backend can have a pointer to a tuple located in a pinned buffer that
can be invalidated by a concurrent heap page vacuum operation.
Heap vacuuming can now be thought of as conceptually similar to index
vacuuming and conceptually dissimilar to heap pruning. Heap pruning now
has sole responsibility for anything involving the logical contents of
the database (e.g., managing transaction status information, recovery
conflicts, considering what to do with HOT chains). Index vacuuming and
heap vacuuming are now only concerned with recycling garbage items from
physical data structures that back the logical database.
Bump XLOG_PAGE_MAGIC due to pruning and heap page vacuum WAL record
changes.
Credit for the idea of retrying pruning a page to avoid the tupgone case
goes to Andres Freund.
Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Masahiko Sawada <sawada.mshk@gmail.com>
Discussion: https://postgr.es/m/CAH2-WznneCXTzuFmcwx_EyRQgfsfJAAsu+CsqRFmFXCAar=nJw@mail.gmail.com
Add a lazy_scan_heap() subsidiary function that handles heap pruning and
tuple freezing: lazy_scan_prune(). This is a great deal cleaner. The
code that remains in lazy_scan_heap()'s per-block loop can now be
thought of as code that either comes before or after the call to
lazy_scan_prune(), which is now the clear focal point. This division is
enforced by the way in which we now manage state. lazy_scan_prune()
outputs state (using its own struct) that describes what to do with the
page following pruning and freezing (e.g., visibility map maintenance,
recording free space in the FSM). It doesn't get passed any special
instructional state from the preamble code, though.
Also cleanly separate the logic used by a VACUUM with INDEX_CLEANUP=off
from the logic used by single-heap-pass VACUUMs. The former case is now
structured as the omission of index and heap vacuuming by a two pass
VACUUM. The latter case goes back to being used only when the table
happens to have no indexes (just as it was before commit a96c41fe).
This structure is much more natural, since the whole point of
INDEX_CLEANUP=off is to skip the index and heap vacuuming that would
otherwise take place. The single-heap-pass case doesn't skip any useful
work, though -- it just does heap pruning and heap vacuuming together
when the table happens to have no indexes.
Both of these changes are preparation for an upcoming patch that
generalizes the mechanism used by INDEX_CLEANUP=off. The later patch
will allow VACUUM to give up on index and heap vacuuming dynamically, as
problems emerge (e.g., with wraparound), so that an affected VACUUM
operation can finish up as soon as possible.
Also fix a very old bug in single-pass VACUUM VERBOSE output. We were
reporting the number of tuples deleted via pruning as a direct
substitute for reporting the number of LP_DEAD items removed in a
function that deals with the second pass over the heap. But that
doesn't work at all -- they're two different things.
To fix, start tracking the total number of LP_DEAD items encountered
during pruning, and use that in the report instead. A single pass
VACUUM will always vacuum away whatever LP_DEAD items a heap page has
immediately after it is pruned, so the total number of LP_DEAD items
encountered during pruning equals the total number vacuumed-away.
(They are _not_ equal in the INDEX_CLEANUP=off case, but that's okay
because skipping index vacuuming is now a totally orthogonal concept to
one-pass VACUUM.)
Also stop reporting the count of LP_UNUSED items in VACUUM VERBOSE
output. This makes the output of VACUUM VERBOSE more consistent with
log_autovacuum's output (because it never showed information about
LP_UNUSED items). VACUUM VERBOSE reported LP_UNUSED items left behind
by the last VACUUM, and LP_UNUSED items created via pruning HOT chains
during the current VACUUM (it never included LP_UNUSED items left behind
by the current VACUUM's second pass over the heap). This makes it
useless as an indicator of line pointer bloat, which must have been the
original intention. (Like the first VACUUM VERBOSE issue, this issue was
arguably an oversight in commit 282d2a03, which added the heap-only
tuple optimization.)
Finally, stop reporting empty_pages in VACUUM VERBOSE output, and start
reporting pages_removed instead. This also makes the output of VACUUM
VERBOSE more consistent with log_autovacuum's output (which does not
show empty_pages, but does show pages_removed). An empty page isn't
meaningfully different to a page that is almost empty, or a page that is
empty but for only a small number of remaining LP_UNUSED items.
Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Robert Haas <robertmhaas@gmail.com>
Reviewed-By: Masahiko Sawada <sawada.mshk@gmail.com>
Discussion: https://postgr.es/m/CAH2-WznneCXTzuFmcwx_EyRQgfsfJAAsu+CsqRFmFXCAar=nJw@mail.gmail.com
Andrew Gierth reported that it's possible to crash the backend if no
pg_attrdef record is found to match an attribute that has atthasdef set.
AttrDefaultFetch warns about this situation, but then leaves behind
a relation tupdesc that has null "adbin" pointer(s), which most places
don't guard against.
We considered promoting the warning to an error, but throwing errors
during relcache load is pretty drastic: it effectively locks one out
of using the relation at all. What seems better is to leave the
load-time behavior as a warning, but then throw an error in any code
path that wants to use a default and can't find it. This confines
the error to a subset of INSERT/UPDATE operations on the table, and
in particular will at least allow a pg_dump to succeed.
Also, we should fix AttrDefaultFetch to not leave any null pointers
in the tupdesc, because that just creates an untested bug hazard.
While at it, apply the same philosophy of "warn at load, throw error
only upon use of the known-missing info" to CHECK constraints.
CheckConstraintFetch is very nearly the same logic as AttrDefaultFetch,
but for reasons lost in the mists of time, it was throwing ERROR for
the same cases that AttrDefaultFetch treats as WARNING. Make the two
functions more nearly alike.
In passing, get rid of potentially-O(N^2) loops in equalTupleDesc
by making AttrDefaultFetch sort the entries after fetching them,
so that equalTupleDesc can assume that entries in two equal tupdescs
must be in matching order. (CheckConstraintFetch already was sorting
CHECK constraints, but equalTupleDesc hadn't been told about it.)
There's some argument for back-patching this, but with such a small
number of field reports, I'm content to fix it in HEAD.
Discussion: https://postgr.es/m/87pmzaq4gx.fsf@news-spur.riddles.org.uk
Previously if hot standby was enabled, archive recovery exited with
an error when it found WAL generated with wal_level=minimal.
But if hot standby was disabled, it just reported a warning and
continued in that case. Which could lead to data loss or errors
during normal operation. A warning was emitted, but users could
easily miss that and not notice this serious situation until
they encountered the actual errors.
To improve this situation, this commit changes archive recovery
so that it exits with FATAL error when it finds WAL generated with
wal_level=minimal whatever the setting of hot standby. This enables
users to notice the serious situation soon.
The FATAL error is thrown if archive recovery starts from a base
backup taken before wal_level is changed to minimal. When archive
recovery exits with the error, if users have a base backup taken
after setting wal_level to higher than minimal, they can recover
the database by starting archive recovery from that newer backup.
But note that if such backup doesn't exist, there is no easy way to
complete archive recovery, which may make the database server
unstartable and users may lose whole database. The commit adds
the note about this risk into the document.
Even in the case of unstartable database server, previously by just
disabling hot standby users could avoid the error during archive
recovery, forcibly start up the server and salvage data from it.
But note that this commit makes this procedure unavailable at all.
Author: Takamichi Osumi
Reviewed-by: Laurenz Albe, Kyotaro Horiguchi, David Steele, Fujii Masao
Discussion: https://postgr.es/m/OSBPR01MB4888CBE1DA08818FD2D90ED8EDF90@OSBPR01MB4888.jpnprd01.prod.outlook.com
Commit 49f49def took entirely the wrong approach to fixing this issue.
Just allocate a local buffer access strategy in each individual worker
instead of trying to propagate state. This state was never propagated
by parallel VACUUM in the first place.
It looks like the only reason that this worked following commit 40d964ec
was that it involved static global variables, which are initialized to 0
per the C standard.
A more comprehensive fix may be necessary, even on HEAD. This fix
should at least get the buildfarm green once again.
Thanks once again to Thomas Munro for continued off-list assistance with
the issue.
Not much to say here: does what it says on the tin.
We steal a previously-always-zero bit from the nextOffset
field of leaf index tuples in order to track whether there
is a nulls bitmap. Otherwise it works about like included
columns in other index types.
Pavel Borisov, reviewed by Andrey Borodin and Anastasia Lubennikova,
and rather heavily editorialized on by me
Discussion: https://postgr.es/m/CALT9ZEFi-vMp4faht9f9Junb1nO3NOSjhpxTmbm1UGLMsLqiEQ@mail.gmail.com
Parallel VACUUM relied on global variable state from the leader process
being propagated to workers on fork(). Commit b4af70cb removed most
uses of global variables inside vacuumlazy.c, but did not account for
the buffer access strategy state.
To fix, propagate the state through shared memory instead.
Per buildfarm failures on elver, curculio, and morepork.
Many thanks to Thomas Munro for off-list assistance with this issue.
Robert Haas
Michael Paquier
Peter Geoghegan
Daniel Gustafsson
Tomas Vondra
Alvaro Herrera
Tom Lane
Peter Eisentraut
Andres Freund
Fujii Masao
Amit Kapila
Noah Misch
John Naylor
Thomas Munro
Heikki Linnakangas
Andrew Dunstan
David Rowley