During crash recovery, we remove disk files belonging to temporary tables,
but the system catalog entries for such tables are intentionally not
cleaned up right away. Instead, the first backend that uses a temp schema
is expected to clean out any leftover objects therein. This approach
requires that we be careful to ignore leftover temp tables (since any
actual access attempt would fail), *even if their BackendId matches our
session*, if we have not yet established use of the session's corresponding
temp schema. That worked fine in the past, but was broken by commit
debcec7dc3 which incorrectly removed the
rd_islocaltemp relcache flag. Put it back, and undo various changes
that substituted tests like "rel->rd_backend == MyBackendId" for use
of a state-aware flag. Per trouble report from Heikki Linnakangas.
Back-patch to 9.1 where the erroneous change was made. In the back
branches, be careful to add rd_islocaltemp in a spot in the struct that
was alignment padding before, so as not to break existing add-on code.
We failed to ever fill the sixth line (LISTEN_ADDR), which caused the
attempt to fill the seventh line (SHMEM_KEY) to fail, so that the shared
memory key never got added to the file in standalone mode. This has been
broken since we added more content to our lock files in 9.1.
To fix, tweak the logic in CreateLockFile to add an empty LISTEN_ADDR
line in standalone mode. This is a tad grotty, but since that function
already knows almost everything there is to know about the contents of
lock files, it doesn't seem that it's any better to hack it elsewhere.
It's not clear how significant this bug really is, since a standalone
backend should never have any children and thus it seems not critical
to be able to check the nattch count of the shmem segment externally.
But I'm going to back-patch the fix anyway.
This problem had escaped notice because of an ancient (and in hindsight
pretty dubious) decision to suppress LOG-level messages by default in
standalone mode; so that the elog(LOG) complaint in AddToDataDirLockFile
that should have warned of the problem didn't do anything. Fixing that
is material for a separate patch though.
Before this patch, streaming replication would refuse to start replicating
if the timeline in the primary doesn't exactly match the standby. The
situation where it doesn't match is when you have a master, and two
standbys, and you promote one of the standbys to become new master.
Promoting bumps up the timeline ID, and after that bump, the other standby
would refuse to continue.
There's significantly more timeline related logic in streaming replication
now. First of all, when a standby connects to primary, it will ask the
primary for any timeline history files that are missing from the standby.
The missing files are sent using a new replication command TIMELINE_HISTORY,
and stored in standby's pg_xlog directory. Using the timeline history files,
the standby can follow the latest timeline present in the primary
(recovery_target_timeline='latest'), just as it can follow new timelines
appearing in an archive directory.
START_REPLICATION now takes a TIMELINE parameter, to specify exactly which
timeline to stream WAL from. This allows the standby to request the primary
to send over WAL that precedes the promotion. The replication protocol is
changed slightly (in a backwards-compatible way although there's little hope
of streaming replication working across major versions anyway), to allow
replication to stop when the end of timeline reached, putting the walsender
back into accepting a replication command.
Many thanks to Amit Kapila for testing and reviewing various versions of
this patch.
If a tuple is larger than page size minus space reserved for fillfactor,
heap_multi_insert would never find a page that it fits in and repeatedly ask
for a new page from RelationGetBufferForTuple. If a tuple is too large to
fit on any page, taking fillfactor into account, RelationGetBufferForTuple
will always expand the relation. In a normal insert, heap_insert will accept
that and put the tuple on the new page. heap_multi_insert, however, does a
fillfactor check of its own, and doesn't accept the newly-extended page
RelationGetBufferForTuple returns, even though there is no other choice to
make the tuple fit.
Fix that by making the logic in heap_multi_insert more like the heap_insert
logic. The first tuple is always put on the page RelationGetBufferForTuple
gives us, and the fillfactor check is only applied to the subsequent tuples.
Report from David Gould, although I didn't use his patch.
The dynahash code requires the number of buckets in a hash table to fit
in an int; but since we calculate the desired hash table size dynamically,
there are various scenarios where we might calculate too large a value.
The resulting overflow can lead to infinite loops, division-by-zero
crashes, etc. I (tgl) had previously installed some defenses against that
in commit 299d171652, but that covered only one
call path. Moreover it worked by limiting the request size to work_mem,
but in a 64-bit machine it's possible to set work_mem high enough that the
problem appears anyway. So let's fix the problem at the root by installing
limits in the dynahash.c functions themselves.
Trouble report and patch by Jeff Davis.
In situations where there are over 8MB of empty pages at the end of
a table, the truncation work for trailing empty pages takes longer
than deadlock_timeout, and there is frequent access to the table by
processes other than autovacuum, there was a problem with the
autovacuum worker process being canceled by the deadlock checking
code. The truncation work done by autovacuum up that point was
lost, and the attempt tried again by a later autovacuum worker. The
attempts could continue indefinitely without making progress,
consuming resources and blocking other processes for up to
deadlock_timeout each time.
This patch has the autovacuum worker checking whether it is
blocking any other thread at 20ms intervals. If such a condition
develops, the autovacuum worker will persist the work it has done
so far, release its lock on the table, and sleep in 50ms intervals
for up to 5 seconds, hoping to be able to re-acquire the lock and
try again. If it is unable to get the lock in that time, it moves
on and a worker will try to continue later from the point this one
left off.
While this patch doesn't change the rules about when and what to
truncate, it does cause the truncation to occur sooner, with less
blocking, and with the consumption of fewer resources when there is
contention for the table's lock.
The only user-visible change other than improved performance is
that the table size during truncation may change incrementally
instead of just once.
This problem exists in all supported versions but is infrequently
reported, although some reports of performance problems when
autovacuum runs might be caused by this. Initial commit is just the
master branch, but this should probably be backpatched once the
build farm and general developer usage confirm that there are no
surprising effects.
Jan Wieck
EndRecPtr is the last record that we've read, but not necessarily yet
replayed. CheckRecoveryConsistency should compare minRecoveryPoint with the
last replayed record instead. This caused recovery to think it's reached
consistency too early.
Now that we do the check in CheckRecoveryConsistency correctly, we have to
move the call of that function to after redoing a record. The current place,
after reading a record but before replaying it, is wrong. In particular, if
there are no more records after the one ending at minRecoveryPoint, we don't
enter hot standby until one extra record is generated and read by the
standby, and CheckRecoveryConsistency is called. These two bugs conspired
to make the code appear to work correctly, except for the small window
between reading the last record that reaches minRecoveryPoint, and
replaying it.
In the passing, rename recoveryLastRecPtr, which is the last record
replayed, to lastReplayedEndRecPtr. This makes it slightly less confusing
with replayEndRecPtr, which is the last record read that we're about to
replay.
Original report from Kyotaro HORIGUCHI, further diagnosis by Fujii Masao.
Backpatch to 9.0, where Hot Standby subtly changed the test from
"minRecoveryPoint < EndRecPtr" to "minRecoveryPoint <= EndRecPtr". The
former works because where the test is performed, we have always read one
more record than we've replayed.
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.
Per report from Kyotaro HORIGUCHI. Backpatch to 8.4. Before that,
minRecoveryPoint was not updated during recovery at all.
Forgot to update it at the right place. Also, consider checkpoint record
that switches to new timelne to be on the new timeline.
This fixes erroneous "requested timeline 2 does not contain minimum recovery
point" errors, pointed out by Amit Kapila while testing another patch.
Commit 729205571e added privileges on data
types, but there were a number of oversights. The implementation of
default privileges for types missed a few places, and pg_dump was
utterly innocent of the whole concept. Per bug #7741 from Nathan Alden,
and subsequent wider investigation.
This patch makes "simple" views automatically updatable, without the need
to create either INSTEAD OF triggers or INSTEAD rules. "Simple" views
are those classified as updatable according to SQL-92 rules. The rewriter
transforms INSERT/UPDATE/DELETE commands on such views directly into an
equivalent command on the underlying table, which will generally have
noticeably better performance than is possible with either triggers or
user-written rules. A view that has INSTEAD OF triggers or INSTEAD rules
continues to operate the same as before.
For the moment, security_barrier views are not considered simple.
Also, we do not support WITH CHECK OPTION. These features may be
added in future.
Dean Rasheed, reviewed by Amit Kapila
Background workers are postmaster subprocesses that run arbitrary
user-specified code. They can request shared memory access as well as
backend database connections; or they can just use plain libpq frontend
database connections.
Modules listed in shared_preload_libraries can register background
workers in their _PG_init() function; this is early enough that it's not
necessary to provide an extra GUC option, because the necessary extra
resources can be allocated early on. Modules can install more than one
bgworker, if necessary.
Care is taken that these extra processes do not interfere with other
postmaster tasks: only one such process is started on each ServerLoop
iteration. This means a large number of them could be waiting to be
started up and postmaster is still able to quickly service external
connection requests. Also, shutdown sequence should not be impacted by
a worker process that's reasonably well behaved (i.e. promptly responds
to termination signals.)
The current implementation lets worker processes specify their start
time, i.e. at what point in the server startup process they are to be
started: right after postmaster start (in which case they mustn't ask
for shared memory access), when consistent state has been reached
(useful during recovery in a HOT standby server), or when recovery has
terminated (i.e. when normal backends are allowed).
In case of a bgworker crash, actions to take depend on registration
data: if shared memory was requested, then all other connections are
taken down (as well as other bgworkers), just like it were a regular
backend crashing. The bgworker itself is restarted, too, within a
configurable timeframe (which can be configured to be never).
More features to add to this framework can be imagined without much
effort, and have been discussed, but this seems good enough as a useful
unit already.
An elementary sample module is supplied.
Author: Álvaro Herrera
This patch is loosely based on prior patches submitted by KaiGai Kohei,
and unsubmitted code by Simon Riggs.
Reviewed by: KaiGai Kohei, Markus Wanner, Andres Freund,
Heikki Linnakangas, Simon Riggs, Amit Kapila
When deleteOneObject closes and reopens the pg_depend relation,
we must see to it that the relcache pointer held by the calling function
(typically performMultipleDeletions) is updated. Usually the relcache
entry is retained so that the pointer value doesn't change, which is why
the problem had escaped notice ... but after a cache flush event there's
no guarantee that the same memory will be reassigned. To fix, change
the recursive functions' APIs so that we pass around a "Relation *"
not just "Relation".
Per investigation of occasional buildfarm failures. This is trivial
to reproduce with -DCLOBBER_CACHE_ALWAYS, which points up the sad
lack of any buildfarm member running that way on a regular basis.
If we're not in hot standby mode, then there's no way for users to connect
to reset the recoveryPause flag, so we shouldn't pause. The code was aware
of this but the test to see if pausing was safe was seriously inadequate:
it wasn't paying attention to reachedConsistency, and besides what it was
testing was that we could legally enter hot standby, not that we have
done so. Get rid of that in favor of checking LocalHotStandbyActive,
which because of the coding in CheckRecoveryConsistency is tantamount to
checking that we have told the postmaster to enter hot standby.
Also, move the recoveryPausesHere() call that reacts to asynchronous
recoveryPause requests so that it's not in the middle of application of a
WAL record. I put it next to the recoveryStopsHere() call --- in future
those are going to need to interact significantly, so this seems like a
good waystation.
Also, don't bother trying to read another WAL record if we've already
decided not to continue recovery. This was no big deal when the code was
written originally, but now that reading a record might entail actions like
fetching an archive file, it seems a bit silly to do it like that.
Per report from Jeff Janes and subsequent discussion. The pause feature
needs quite a lot more work, but this gets rid of some indisputable bugs,
and seems safe enough to back-patch.
When waiting for an XLOG_BACKUP_RECORD the minRecoveryPoint
will be incorrect, so we must not declare recovery as consistent
before we have seen the record. Major bug allowing recovery to end
too early in some cases, allowing people to see inconsistent db.
This patch to HEAD and 9.2, other fix required for 9.1 and 9.0
Simon Riggs and Andres Freund, bug report by Jeff Janes
This allows us to do some more rigorous sanity checking for various
incorrect point-in-time recovery scenarios, and provides more information
for debugging purposes. It will also come handy in the upcoming patch to
allow timeline switches to be replicated by streaming replication.
This allows recovery to notice certain incorrect recovery scenarios.
If a server has recovered to point X on timeline 5, and you restart
recovery, it better be on timeline 5 when it reaches point X again, not on
some timeline with a higher ID. This can happen e.g if you a standby server
is shut down, a new timeline appears in the WAL archive, and the standby
server is restarted. It will try to follow the new timeline, which is wrong
because some WAL on the old timeline was already replayed before shutdown.
Requires an initdb (or at least pg_resetxlog), because this adds a field to
the control file.
During VACUUM if we pause to perform a cycle
of index cleanup we drop the vmbuffer pin,
so we should do the same thing when heap
scan completes. This avoids holding vmbuffer
pin across the main index cleanup in VACUUM,
which could be minutes or hours longer than
necessary for correctness.
Bug report and suggested fix from Pavan Deolasee
Rename PGXACT->inCommit flag into delayChkpt flag,
and generalise comments to allow use in other situations,
such as the forthcoming potential use in checksum patch.
Replace wait loop to look for VXIDs with delayChkpt set.
No user visible changes, not behaviour changes at present.
Simon Riggs, reviewed and rebased by Jeff Davis
Update README to explain prerequisites for
correct access to LSN fields of a page.
Independent chunk removed from checksums
patch to reduce size of patch.
Allow support only for freezing tuples by explicit
command. Previous coding mistakenly extended
slightly beyond what was agreed as correct on -hackers.
So essentially a partial revoke of earlier work,
leaving just the COPY FREEZE command.
This reverts commit c11130690d in favor of
actually fixing the problem: namely, that we should never have been
modifying the checkpoint record's nextXid at this point to begin with.
The nextXid should match the state as of the checkpoint's logical WAL
position (ie the redo point), not the state as of its physical position.
It's especially bogus to advance it in some wal_levels and not others.
In any case there is no need for the checkpoint record to carry the
same nextXid shown in the XLOG_RUNNING_XACTS record just emitted by
LogStandbySnapshot, as any replay operation will already have adopted
that value as current.
This fixes bug #7710 from Tarvi Pillessaar, and probably also explains bug
#6291 from Daniel Farina, in that if a checkpoint were in progress at the
instant of XID wraparound, the epoch bump would be lost as reported.
(And, of course, these days there's at least a 50-50 chance of a checkpoint
being in progress at any given instant.)
Diagnosed by me and independently by Andres Freund. Back-patch to all
branches supporting hot standby.
Previously we stored all xids mixed together.
Now we store top-level xids first, followed
by all subxids. Also skip logging any subxids
if the snapshot is suboverflowed, since there
are potentially large numbers of them and they
are not useful in that case anyway. Has value
in the envisaged design for decoding of WAL.
No planned effect on Hot Standby.
Andres Freund, reviewed by me
If wal_level = hot_standby we update the checkpoint nextxid,
though in the case where a wraparound occurred half-way through
a checkpoint we would neglect updating the epoch also. Updating
the nextxid is arguably the wrong thing to do, but changing that
may introduce subtle bugs into hot standby startup, while updating
the value doesn't cause any known bugs yet. Minimal fix now to
HEAD and backbranches, wider fix later in HEAD.
Bug reported in #6291 by Daniel Farina and slightly differently in
Cause analysis and recommended fixes from Tom Lane and Andres Freund.
Applied patch is minimal version of Andres Freund's work.
Normally it is unsafe to allow ALTER TYPE ADD VALUE in a transaction block,
because instances of the value could be added to indexes later in the same
transaction, and then they would still be accessible even if the
transaction rolls back. However, we can allow this if the enum type itself
was created in the current transaction, because then any such indexes would
have to go away entirely on rollback.
The reason for allowing this is to support pg_upgrade's new usage of
pg_restore --single-transaction: in --binary-upgrade mode, pg_dump emits
enum types as a succession of ALTER TYPE ADD VALUE commands so that it can
preserve the values' OIDs. The support is a bit limited, so we'll leave
it undocumented.
Andres Freund
When a relfilenode is created in this subtransaction or
a committed child transaction and it cannot otherwise
be seen by our own process, mark tuples committed ahead
of transaction commit for all COPY commands in same
transaction. If FREEZE specified on COPY
and pre-conditions met then rows will also be frozen.
Both options designed to avoid revisiting rows after commit,
increasing performance of subsequent commands after
data load and upgrade. pg_restore changes later.
Simon Riggs, review comments from Heikki Linnakangas, Noah Misch and design
input from Tom Lane, Robert Haas and Kevin Grittner
If we had not been holding buffer pin continuously since the tuple was
initially fetched by the UPDATE or DELETE query, it would be possible for
VACUUM or a page-prune operation to move the tuple while we're trying to
copy it. This would result in a garbage "old" tuple value being passed to
an AFTER ROW UPDATE or AFTER ROW DELETE trigger. The preconditions for
this are somewhat improbable, and the timing constraints are very tight;
so it's not so surprising that this hasn't been reported from the field,
even though the bug has been there a long time.
Problem found by Andres Freund. Back-patch to all active branches.
The length of a socket path name is constrained by the size of struct
sockaddr_un, and there's not a lot we can do about it since that is a
kernel API. However, it would be a good thing if we produced an
intelligible error message when the user specifies a socket path that's too
long --- and getaddrinfo's standard API is too impoverished to do this in
the natural way. So insert explicit tests at the places where we construct
a socket path name. Now you'll get an error that makes sense and even
tells you what the limit is, rather than something generic like
"Non-recoverable failure in name resolution".
Per trouble report from Jeremy Drake and a fix idea from Andrew Dunstan.
There are probably other places where this can be used, but for now,
this just makes MergeAppend use it, so that this code will have test
coverage. There is other work in the queue that will use this, as
well.
Abhijit Menon-Sen, reviewed by Andres Freund, Robert Haas, Álvaro
Herrera, Tom Lane, and others.
Commit 8cb53654db, which introduced DROP
INDEX CONCURRENTLY, managed to break CREATE INDEX CONCURRENTLY via a poor
choice of catalog state representation. The pg_index state for an index
that's reached the final pre-drop stage was the same as the state for an
index just created by CREATE INDEX CONCURRENTLY. This meant that the
(necessary) change to make RelationGetIndexList ignore about-to-die indexes
also made it ignore freshly-created indexes; which is catastrophic because
the latter do need to be considered in HOT-safety decisions. Failure to
do so leads to incorrect index entries and subsequently wrong results from
queries depending on the concurrently-created index.
To fix, add an additional boolean column "indislive" to pg_index, so that
the freshly-created and about-to-die states can be distinguished. (This
change obviously is only possible in HEAD. This patch will need to be
back-patched, but in 9.2 we'll use a kluge consisting of overloading the
formerly-impossible state of indisvalid = true and indisready = false.)
In addition, change CREATE/DROP INDEX CONCURRENTLY so that the pg_index
flag changes they make without exclusive lock on the index are made via
heap_inplace_update() rather than a normal transactional update. The
latter is not very safe because moving the pg_index tuple could result in
concurrent SnapshotNow scans finding it twice or not at all, thus possibly
resulting in index corruption. This is a pre-existing bug in CREATE INDEX
CONCURRENTLY, which was copied into the DROP code.
In addition, fix various places in the code that ought to check to make
sure that the indexes they are manipulating are valid and/or ready as
appropriate. These represent bugs that have existed since 8.2, since
a failed CREATE INDEX CONCURRENTLY could leave a corrupt or invalid
index behind, and we ought not try to do anything that might fail with
such an index.
Also fix RelationReloadIndexInfo to ensure it copies all the pg_index
columns that are allowed to change after initial creation. Previously we
could have been left with stale values of some fields in an index relcache
entry. It's not clear whether this actually had any user-visible
consequences, but it's at least a bug waiting to happen.
In addition, do some code and docs review for DROP INDEX CONCURRENTLY;
some cosmetic code cleanup but mostly addition and revision of comments.
This will need to be back-patched, but in a noticeably different form,
so I'm committing it to HEAD before working on the back-patch.
Problem reported by Amit Kapila, diagnosis by Pavan Deolassee,
fix by Tom Lane and Andres Freund.
This was apparently a typo, which caused recovery to think that it
immediately reached the end of backup, and allowed the database to start
up too early.
Reported by Jeff Janes. Backpatch to 9.2, where this code was introduced.
Files opened with BasicOpenFile or PathNameOpenFile are not automatically
cleaned up on error. That puts unnecessary burden on callers that only want
to keep the file open for a short time. There is AllocateFile, but that
returns a buffered FILE * stream, which in many cases is not the nicest API
to work with. So add function called OpenTransientFile, which returns a
unbuffered fd that's cleaned up like the FILE* returned by AllocateFile().
This plugs a few rare fd leaks in error cases:
1. copy_file() - fixed by by using OpenTransientFile instead of BasicOpenFile
2. XLogFileInit() - fixed by adding close() calls to the error cases. Can't
use OpenTransientFile here because the fd is supposed to persist over
transaction boundaries.
3. lo_import/lo_export - fixed by using OpenTransientFile instead of
PathNameOpenFile.
In addition to plugging those leaks, this replaces many BasicOpenFile() calls
with OpenTransientFile() that were not leaking, because the code meticulously
closed the file on error. That wasn't strictly necessary, but IMHO it's good
for robustness.
The same leaks exist in older versions, but given the rarity of the issues,
I'm not backpatching this. Not yet, anyway - it might be good to backpatch
later, after this mechanism has had some more testing in master branch.
This reverts commit d573e239f0, "Take fewer
snapshots". While that seemed like a good idea at the time, it caused
execution to use a snapshot that had been acquired before locking any of
the tables mentioned in the query. This created user-visible anomalies
that were not present in any prior release of Postgres, as reported by
Tomas Vondra. While this whole area could do with a redesign (since there
are related cases that have anomalies anyway), it doesn't seem likely that
any future patch would be reasonably back-patchable; and we don't want 9.2
to exhibit a behavior that's subtly unlike either past or future releases.
Hence, revert to prior code while we rethink the problem.
In a query such as "SELECT DISTINCT min(x) FROM tab", the DISTINCT is
pretty useless (there being only one output row), but nonetheless it
shouldn't fail. But it could fail if "tab" is an inheritance parent,
because planagg.c's code for fixing up equivalence classes after making the
index-optimized MIN/MAX transformation wasn't prepared to find child-table
versions of the aggregate expression. The least ugly fix seems to be
to add an option to mutate_eclass_expressions() to skip child-table
equivalence class members, which aren't used anymore at this stage of
planning so it's not really necessary to fix them. Since child members
are ignored in many cases already, it seems plausible for
mutate_eclass_expressions() to have an option to ignore them too.
Per bug #7703 from Maxim Boguk.
Back-patch to 9.1. Although the same code exists before that, it cannot
encounter child-table aggregates AFAICS, because the index optimization
transformation cannot succeed on inheritance trees before 9.1 (for lack
of MergeAppend).
When startup process opens a WAL segment after replaying part of it, it
validates the first page on the WAL segment, even though the page it's
really interested in later in the file. As part of the validation, it checks
that the TLI on the page header is >= the TLI it saw on the last page it
read. If the segment contains a timeline switch, and we have already
replayed it, and then re-open the WAL segment (because of streaming
replication got disconnected and reconnected, for example), the TLI check
will fail when the first page is validated. Fix that by relaxing the TLI
check when re-opening a WAL segment.
Backpatch to 9.0. Earlier versions had the same code, but before standby
mode was introduced in 9.0, recovery never tried to re-read a segment after
partially replaying it.
Reported by Amit Kapila, while testing a new feature.
Once we've received a shutdown signal (SIGINT or SIGTERM), we should not
launch any more child processes, even if we get signals requesting such.
The normal code path for spawning backends has always understood that,
but the postmaster's infrastructure for hot standby and autovacuum didn't
get the memo. As reported by Hari Babu in bug #7643, this could lead to
failure to shut down at all in some cases, such as when SIGINT is received
just before the startup process sends PMSIGNAL_RECOVERY_STARTED: we'd
launch a bgwriter and checkpointer, and then those processes would have no
idea that they ought to quit. Similarly, launching a new autovacuum worker
would result in waiting till it finished before shutting down.
Also, switch the order of the code blocks in reaper() that detect startup
process crash versus shutdown termination. Once we've sent it a signal,
we should not consider that exit(1) is surprising. This is just a cosmetic
fix since shutdown occurs correctly anyway, but better not to log a phony
complaint about startup process crash.
Back-patch to 9.0. Some parts of this might be applicable before that,
but given the lack of prior complaints I'm not going to worry too much
about older branches.
In many functions, a NumericVar was initialized from an input Numeric, to be
passed as input to a calculation function. When the NumericVar is not
modified, the digits array of the NumericVar can point directly to the digits
array in the original Numeric, and we can avoid a palloc() and memcpy(). Add
init_var_from_num() function to initialize a var like that.
Remove dscale argument from get_str_from_var(), as all the callers just
passed the dscale of the variable. That means that the rounding it used to
do was not actually necessary, and get_str_from_var() no longer scribbles on
its input. That makes it safer in general, and allows us to use the new
init_var_from_num() function in e.g numeric_out().
Also modified numericvar_to_int8() to no scribble on its input either. It
creates a temporary copy to avoid that. To compensate, the callers no longer
need to create a temporary copy, so the net # of pallocs is the same, but this
is nicer.
In the passing, use a constant for the number 10 in get_str_from_var_sci(),
when calculating 10^exponent. Saves a palloc() and some cycles to convert
integer 10 to numeric.
Original patch by Kyotaro HORIGUCHI, with further changes by me. Reviewed
by Pavel Stehule.
Some platforms throw an exception for this division, rather than returning
a necessarily-overflowed result. Since we were testing for overflow after
the fact, an exception isn't nice. We can avoid the problem by treating
division by -1 as negation.
Add some regression tests so that we'll find out if any compilers try to
optimize away the overflow check conditions.
This ought to be back-patched, but I'm going to see what the buildfarm
reports about the regression tests first.
Per discussion with Xi Wang, though this is different from the patch he
submitted.
When I moved ExecuteRecoveryCommand() from xlog.c to xlogarchive.c, I didn't
realize that it's called from the checkpoint process, not the startup
process. I tried to use InRedo variable to decide whether or not to attempt
cleaning up the archive (must not do so before we have read the initial
checkpoint record), but that variable is only valid within the startup
process.
Instead, let ExecuteRecoveryCommand() always clean up the archive, and add
an explicit argument to RestoreArchivedFile() to say whether that's allowed
or not. The caller knows better.
Reported by Erik Rijkers, diagnosis by Fujii Masao. Only 9.3devel is
affected.
The previous definitions of these GUC variables allowed them to range
up to INT_MAX, but in point of fact the underlying code would suffer
overflows or other errors with large values. Reduce the maximum values
to something that won't misbehave. There's no apparent value in working
harder than this, since very large delays aren't sensible for any of
these. (Note: the risk with archive_timeout is that if we're late
checking the state, the timestamp difference it's being compared to
might overflow. So we need some amount of slop; the choice of INT_MAX/2
is arbitrary.)
Per followup investigation of bug #7670. Although this isn't a very
significant fix, might as well back-patch.
We need to avoid calling WaitLatch with timeouts exceeding INT_MAX.
Fortunately a simple clamp will do the trick, since no harm is done if
the wait times out before it's really time to rotate the log file.
Per bug #7670 (probably bug #7545 is the same thing, too).
In passing, fix bogus definition of log_rotation_age's maximum value in
guc.c --- it was numerically right, but only because MINS_PER_HOUR and
SECS_PER_MINUTE have the same value.
Back-patch to 9.2. Before that, syslogger wasn't using WaitLatch.
The behavior with larger values is unspecified by the Single Unix Spec.
It appears that BSD-derived kernels report EINVAL, although Linux does not.
If waiting for longer intervals is desired, the calling code has to do
something to limit the delay; we can't portably fix it here since "long"
may not be any wider than "int" in the first place.
Part of response to bug #7670, though this change doesn't fix that
(in fact, it converts the problem from an ERROR into an Assert failure).
No back-patch since it's just an assertion addition.
Traditionally check_partial_indexes() has only looked at restriction
clauses while trying to prove partial indexes usable in queries. However,
join clauses can also be used in some cases; mainly, that a strict operator
on "x" proves an "x IS NOT NULL" index predicate, even if the operator is
in a join clause rather than a restriction clause. Adding this code fixes
a regression in 9.2, because previously we would take join clauses into
account when considering whether a partial index could be used in a
nestloop inner indexscan path. 9.2 doesn't handle nestloop inner
indexscans in the same way, and this consideration was overlooked in the
rewrite. Moving the work to check_partial_indexes() is a better solution
anyway, since the proof applies whether or not we actually use the index
in that particular way, and we don't have to do it over again for each
possible outer relation. Per report from Dave Cramer.
The correct answer for this (or any other case with arg2 = -1) is zero,
but some machines throw a floating-point exception instead of behaving
sanely. Commit f9ac414c35 dealt with this
in int4mod, but overlooked the fact that it also happens in int8mod
(at least on my Linux x86_64 machine). Protect int2mod as well; it's
not clear whether any machines fail there (mine does not) but since the
test is so cheap it seems better safe than sorry. While at it, simplify
the original guard in int4mod: we need only check for arg2 == -1, we
don't need to check arg1 explicitly.
Xi Wang, with some editing by me.
record_out() leaks memory: it fails to free the strings returned by the
per-column output functions, and also is careless about detoasted values.
This results in a query-lifespan memory leakage when returning composite
values to the client, because printtup() runs the output functions in the
query-lifespan memory context. Fix it to handle these issues the same way
printtup() does. Also fix a similar leakage in record_send().
(At some point we might want to try to run output functions in
shorter-lived memory contexts, so that we don't need a zero-leakage policy
for them. But that would be a significantly more invasive patch, which
doesn't seem like material for back-patching.)
In passing, use appendStringInfoCharMacro instead of appendStringInfoChar
in the innermost data-copying loop of record_out, to try to shave a few
cycles from this function's runtime.
Per trouble report from Carlos Henrique Reimer. Back-patch to all
supported versions.
At commit all standby locks are released
for the top-level transaction, so searching
for locks for each subtransaction is both
pointless and costly (N^2) in the presence
of many AccessExclusiveLocks.
Most of the replay functions for WAL record types that modify more than
one page failed to ensure that those pages were locked correctly to ensure
that concurrent queries could not see inconsistent page states. This is
a hangover from coding decisions made long before Hot Standby was added,
when it was hardly necessary to acquire buffer locks during WAL replay
at all, let alone hold them for carefully-chosen periods.
The key problem was that RestoreBkpBlocks was written to hold lock on each
page restored from a full-page image for only as long as it took to update
that page. This was guaranteed to break any WAL replay function in which
there was any update-ordering constraint between pages, because even if the
nominal order of the pages is the right one, any mixture of full-page and
non-full-page updates in the same record would result in out-of-order
updates. Moreover, it wouldn't work for situations where there's a
requirement to maintain lock on one page while updating another. Failure
to honor an update ordering constraint in this way is thought to be the
cause of bug #7648 from Daniel Farina: what seems to have happened there
is that a btree page being split was rewritten from a full-page image
before the new right sibling page was written, and because lock on the
original page was not maintained it was possible for hot standby queries to
try to traverse the page's right-link to the not-yet-existing sibling page.
To fix, get rid of RestoreBkpBlocks as such, and instead create a new
function RestoreBackupBlock that restores just one full-page image at a
time. This function can be invoked by WAL replay functions at the points
where they would otherwise perform non-full-page updates; in this way, the
physical order of page updates remains the same no matter which pages are
replaced by full-page images. We can then further adjust the logic in
individual replay functions if it is necessary to hold buffer locks
for overlapping periods. A side benefit is that we can simplify the
handling of concurrency conflict resolution by moving that code into the
record-type-specfic functions; there's no more need to contort the code
layout to keep conflict resolution in front of the RestoreBkpBlocks call.
In connection with that, standardize on zero-based numbering rather than
one-based numbering for referencing the full-page images. In HEAD, I
removed the macros XLR_BKP_BLOCK_1 through XLR_BKP_BLOCK_4. They are
still there in the header files in previous branches, but are no longer
used by the code.
In addition, fix some other bugs identified in the course of making these
changes:
spgRedoAddNode could fail to update the parent downlink at all, if the
parent tuple is in the same page as either the old or new split tuple and
we're not doing a full-page image: it would get fooled by the LSN having
been advanced already. This would result in permanent index corruption,
not just transient failure of concurrent queries.
Also, ginHeapTupleFastInsert's "merge lists" case failed to mark the old
tail page as a candidate for a full-page image; in the worst case this
could result in torn-page corruption.
heap_xlog_freeze() was inconsistent about using a cleanup lock or plain
exclusive lock: it did the former in the normal path but the latter for a
full-page image. A plain exclusive lock seems sufficient, so change to
that.
Also, remove gistRedoPageDeleteRecord(), which has been dead code since
VACUUM FULL was rewritten.
Back-patch to 9.0, where hot standby was introduced. Note however that 9.0
had a significantly different WAL-logging scheme for GIST index updates,
and it doesn't appear possible to make that scheme safe for concurrent hot
standby queries, because it can leave inconsistent states in the index even
between WAL records. Given the lack of complaints from the field, we won't
work too hard on fixing that branch.
errcontext() is typically used in an error context callback function, not
within an ereport() invocation like e.g errmsg and errdetail are. That means
that the message domain that the TEXTDOMAIN magic in ereport() determines
is not the right one for the errcontext() calls. The message domain needs to
be determined by the C file containing the errcontext() call, not the file
containing the ereport() call.
Fix by turning errcontext() into a macro that passes the TEXTDOMAIN to use
for the errcontext message. "errcontext" was used in a few places as a
variable or struct field name, I had to rename those out of the way, now
that errcontext is a macro.
We've had this problem all along, but this isn't doesn't seem worth
backporting. It's a fairly minor issue, and turning errcontext from a
function to a macro requires at least a recompile of any external code that
calls errcontext().
Since transformSetOperationTree() recurses, it can be driven to stack
overflow with enough UNION/INTERSECT/EXCEPT clauses in a query. Add a
check to ensure it fails cleanly instead of crashing. Per report from
Matthew Gerber (though it's not clear whether this is the only thing
going wrong for him).
Historical note: I think the reasoning behind not putting a check here in
the beginning was that the check in transformExpr() ought to be sufficient
to guard the whole parser. However, because transformSetOperationTree()
recurses all the way to the bottom of the set-operation tree before doing
any analysis of the statement's expressions, that check doesn't save it.
If the sleep is interrupted by a signal, we must recompute the remaining
time to wait; otherwise, a steady stream of non-wait-terminating interrupts
could delay return from WaitLatch indefinitely. This has been shown to be
a problem for the autovacuum launcher, and there may well be other places
now or in the future with similar issues. So we'd better make the function
robust, even though this'll add at least one gettimeofday call per wait.
Back-patch to 9.2. We might eventually need to fix 9.1 as well, but the
code is quite different there, and the usage of WaitLatch in 9.1 is so
limited that it's not clearly important to do so.
Reported and diagnosed by Jeff Janes, though I rewrote his patch rather
heavily.
This function currently lacks the option to throw error if the provided
targetlist doesn't have any matching entry for a Var to be replaced.
Two of the four existing call sites would be better off with an error,
as would the usage in the pending auto-updatable-views patch, so it seems
past time to extend the API to support that. To do so, replace the "event"
parameter (historically of type CmdType, though it was declared plain int)
with a special-purpose enum type.
It's unclear whether this function might be called by third-party code.
Since many C compilers wouldn't warn about a call site continuing to use
the old calling convention, rename the function to forcibly break any
such code that hasn't been updated. The old name was none too well chosen
anyhow.
The trigger and rule cases need to split up the input name list, but
they mustn't corrupt the passed-in data structure, since it could be part
of a cached utility-statement parsetree. Per bug #7641.
Commit 4c9d0901 mistakenly introduced a call to
TransferPredicateLocksToHeapRelation() on an index relation that had
been closed a few lines above. Moving up an index_open() call that's
below is enough to fix the problem.
Discovered by me while testing an unrelated patch.
We used to send structs wrapped in CopyData messages, which works as long as
the client and server agree on things like endianess, timestamp format and
alignment. That's good enough for running a standby server, which has to run
on the same platform anyway, but it's useful for tools like pg_receivexlog
to work across platforms.
This breaks protocol compatibility of streaming replication, but we never
promised that to be compatible across versions, anyway.
This case got broken in 8.4 by the addition of an error check that
complains if ALTER TABLE ONLY is used on a table that has children.
We do use ONLY for this situation, but it's okay because the necessary
recursion occurs at a higher level. So we need to have a separate
flag to suppress recursion without making the error check.
Reported and patched by Pavan Deolasee, with some editorial adjustments by
me. Back-patch to 8.4, since this is a regression of functionality that
worked in earlier branches.
In bug #7626, Brian Dunavant exposes a performance problem created by
commit 3b8968f252: that commit attempted to
consider *all* possible combinations of indexable join clauses, but if said
clauses join to enough different relations, there's an exponential increase
in the number of outer-relation sets considered.
In Brian's example, all the clauses come from the same equivalence class,
which means it's redundant to use more than one of them in an indexscan
anyway. So we can prevent the problem in this class of cases (which is
probably the majority of real examples) by rejecting combinations that
would only serve to add a known-redundant clause.
But that still leaves us exposed to exponential growth of planning time
when the query has a lot of non-equivalence join clauses that are usable
with the same index. I chose to prevent such cases by setting an upper
limit on the number of relation sets considered, equal to ten times the
number of index clauses considered so far. (This sliding limit still
allows new relsets to be added on as we move to additional index columns,
which is probably more important than considering even more combinations of
clauses for the previous column.) This should keep the amount of work done
roughly linear rather than exponential in the apparent query complexity.
This part of the fix is pretty ad-hoc; but without a clearer idea of
real-world cases for which this would result in markedly inferior plans,
it's hard to see how to do better.
Commit dfda6eba (which changed segment numbers to use a single 64 bit
variable instead of log/seg) introduced a couple of bogus choices of
exactly which log segment number variable to use in each case.
This is currently pretty harmless; in one place, the bogus number was
only being used in an error message for a pretty unlikely condition
(failure to fsync a WAL segment file). In the other, it was using a
global variable instead of the local variable; but all callsites were
passing the value of the global variable anyway.
No need to backpatch because that commit is not on earlier branches.
In its original conception, it was leaving some objects into the old
schema, but without their proper pg_depend entries; this meant that the
old schema could be dropped, causing future pg_dump calls to fail on the
affected database. This was originally reported by Jeff Frost as #6704;
there have been other complaints elsewhere that can probably be traced
to this bug.
To fix, be more consistent about altering a table's subsidiary objects
along the table itself; this requires some restructuring in how tables
are relocated when altering an extension -- hence the new
AlterTableNamespaceInternal routine which encapsulates it for both the
ALTER TABLE and the ALTER EXTENSION cases.
There was another bug lurking here, which was unmasked after fixing the
previous one: certain objects would be reached twice via the dependency
graph, and the second attempt to move them would cause the entire
operation to fail. Per discussion, it seems the best fix for this is to
do more careful tracking of objects already moved: we now maintain a
list of moved objects, to avoid attempting to do it twice for the same
object.
Authors: Alvaro Herrera, Dimitri Fontaine
Reviewed by Tom Lane
This prevents surprising behavior when a FOR EACH ROW trigger
BEFORE UPDATE or BEFORE DELETE directly or indirectly updates or
deletes the the old row. Prior to this patch the requested action
on the row could be silently ignored while all triggered actions
based on the occurence of the requested action could be committed.
One example of how this could happen is if the BEFORE DELETE
trigger for a "parent" row deleted "children" which had trigger
functions to update summary or status data on the parent.
This also prevents similar surprising problems if the query has a
volatile function which updates a target row while it is already
being updated.
There are related issues present in FOR UPDATE cursors and READ
COMMITTED queries which are not handled by this patch. These
issues need further evalution to determine what change, if any, is
needed.
Where the new error messages are generated, in most cases the best
fix will be to move code from the BEFORE trigger to an AFTER
trigger. Where this is not feasible, the trigger can avoid the
error by re-issuing the triggering statement and returning NULL.
Documentation changes will be submitted in a separate patch.
Kevin Grittner and Tom Lane with input from Florian Pflug and
Robert Haas, based on problems encountered during conversion of
Wisconsin Circuit Court trigger logic to plpgsql triggers.
generate_base_implied_equalities_const() should prefer plain Consts over
other em_is_const eclass members when choosing the "pivot" value that
all the other members will be equated to. This makes it more likely that
the generated equalities will be useful in constraint-exclusion proofs.
Per report from Rushabh Lathia.
To provide some bias against using a large index when a small one would do
as well, genericcostestimate adds a "fudge factor", which for a long time
was random_page_cost * index_pages/10000. However, this can grow to be the
dominant term in indexscan cost estimates when the index involved is large
enough, a behavior that was never intended. Change to a ln(1 + n/10000)
formulation, which has nearly the same behavior up to a few hundred pages
but tails off significantly thereafter. (A log curve seems correct on
first principles, since what we're trying to account for here is index
descent costs, which are typically logarithmic.) Per bug #7619 from Niko
Kiirala.
Possibly this change should get back-patched, but I'm hesitant to mess with
cost estimates in stable branches.
Views should not have any pg_attribute entries for system columns.
However, we forgot to remove such entries when converting a table to a
view. This could lead to crashes later on, if someone attempted to
reference such a column, as reported by Kohei KaiGai.
Patch in HEAD only. This bug has been there forever, but in the back
branches we will have to defend against existing mis-converted views,
so it doesn't seem worthwhile to change the conversion code too.
... and have sepgsql use it to determine whether to check permissions
during certain operations. Indexes that are being created as a result
of REINDEX, for instance, do not need to have their permissions checked;
they were already checked when the index was created.
Author: KaiGai Kohei, slightly revised by me
For the non-concurrent case there is an AccessExclusiveLock lock
on both the index and the heap at a time during which no other
process is using either, before which the index is maintained and
used for scans, and after which the index is no longer used or
maintained. Predicate locks can safely be moved from the index to
the related heap relation under the protection of these locks.
This was done prior to the introductin of DROP INDEX CONCURRENTLY
and continues to be done for non-concurrent index drops.
For concurrent index drops, the predicate locks must be moved when
there are no index scans in progress on that index and no more can
subsequently start, and before heap inserts stop maintaining the
index. As long as these conditions are guaranteed when the
TransferPredicateLocksToHeapRelation() function is called,
stronger locks are not needed for correctness.
Kevin Grittner based on questions by Tom Lane in reviewing the
DROP INDEX CONCURRENTLY patch and in cooperation with Andres
Freund and Simon Riggs.
The code seems to have been written to handle the pre-parse-analysis
representation, where an ExecuteStmt would appear directly under
CreateTableAsStmt. But in reality the function is only run on
already-parse-analyzed statements, so there will be a Query node in
between. We'd not noticed the bug because the function is generally
not used at all except in extended query protocol.
Per report from Robert Haas and Rushabh Lathia.
An out-of-memory error during expand_table() on a palloc-based hash table
would leave a partially-initialized entry in the table. This would not be
harmful for transient hash tables, since they'd get thrown away anyway at
transaction abort. But for long-lived hash tables, such as the relcache
hash, this would effectively corrupt the table, leading to crash or other
misbehavior later.
To fix, rearrange the order of operations so that table enlargement is
attempted before we insert a new entry, rather than after adding it
to the hash table.
Problem discovered by Hitoshi Harada, though this is a bit different
from his proposed patch.
Canceling DROP INDEX CONCURRENTLY during
wait could allow an orphaned index to be
left behind which could not be dropped.
Backpatch to 9.2
Andres Freund, tested by Abhijit Menon-Sen
Remove useless duplicate initialization of bucket headers, don't use a
dlist_mutable_iter in a performance-critical path that doesn't need it,
make some other cosmetic changes for consistency's sake.
dlist_delete, dlist_insert_after, dlist_insert_before, slist_insert_after
do not need access to the list header, and indeed insisting on that negates
one of the main advantages of a doubly-linked list.
In consequence, revert addition of "cache_bucket" field to CatCTup.
Make foreach macros less syntactically dangerous, and fix some typos in
evidently-never-tested ones. Add missing slist_next_node and
slist_head_node functions. Fix broken dlist_check code. Assorted comment
improvements.
Concurrent behaviour was flawed when using
a two-step process, so add an additional
phase of processing to ensure concurrency
for both SELECTs and INSERT/UPDATE/DELETEs.
Backpatch to 9.2
Andres Freund, tweaked by me
If a potential equivalence clause references a variable from the nullable
side of an outer join, the planner needs to take care that derived clauses
are not pushed to below the outer join; else they may use the wrong value
for the variable. (The problem arises only with non-strict clauses, since
if an upper clause can be proven strict then the outer join will get
simplified to a plain join.) The planner attempted to prevent this type
of error by checking that potential equivalence clauses aren't
outerjoin-delayed as a whole, but actually we have to check each side
separately, since the two sides of the clause will get moved around
separately if it's treated as an equivalence. Bugs of this type can be
demonstrated as far back as 7.4, even though releases before 8.3 had only
a very ad-hoc notion of equivalence clauses.
In addition, we neglected to account for the possibility that such clauses
might have nonempty nullable_relids even when not outerjoin-delayed; so the
equivalence-class machinery lacked logic to compute correct nullable_relids
values for clauses it constructs. This oversight was harmless before 9.2
because we were only using RestrictInfo.nullable_relids for OR clauses;
but as of 9.2 it could result in pushing constructed equivalence clauses
to incorrect places. (This accounts for bug #7604 from Bill MacArthur.)
Fix the first problem by adding a new test check_equivalence_delay() in
distribute_qual_to_rels, and fix the second one by adding code in
equivclass.c and called functions to set correct nullable_relids for
generated clauses. Although I believe the second part of this is not
currently necessary before 9.2, I chose to back-patch it anyway, partly to
keep the logic similar across branches and partly because it seems possible
we might find other reasons why we need valid values of nullable_relids in
the older branches.
Add regression tests illustrating these problems. In 9.0 and up, also
add test cases checking that we can push constants through outer joins,
since we've broken that optimization before and I nearly broke it again
with an overly simplistic patch for this problem.
If an SMgrRelation is not "owned" by a relcache entry, don't allow it to
live past transaction end. This design allows the same SMgrRelation to be
used for blind writes of multiple blocks during a transaction, but ensures
that we don't hold onto such an SMgrRelation indefinitely. Because an
SMgrRelation typically corresponds to open file descriptors at the fd.c
level, leaving it open when there's no corresponding relcache entry can
mean that we prevent the kernel from reclaiming deleted disk space.
(While CacheInvalidateSmgr messages usually fix that, there are cases
where they're not issued, such as DROP DATABASE. We might want to add
some more sinval messaging for that, but I'd be inclined to keep this
type of logic anyway, since allowing VFDs to accumulate indefinitely
for blind-written relations doesn't seem like a good idea.)
This code replaces a previous attempt towards the same goal that proved
to be unreliable. Back-patch to 9.1 where the previous patch was added.
This reverts commit fba105b109.
That approach had problems with the smgr-level state not tracking what
we really want to happen, and with the VFD-level state not tracking the
smgr-level state very well either. In consequence, it was still possible
to hold kernel file descriptors open for long-gone tables (as in recent
report from Tore Halset), and yet there were also cases of FDs being closed
undesirably soon. A replacement implementation will follow.
Provide a common implementation of embedded singly-linked and
doubly-linked lists. "Embedded" in the sense that the nodes'
next/previous pointers exist within some larger struct; this design
choice reduces memory allocation overhead.
Most of the implementation uses inlineable functions (where supported),
for performance.
Some existing uses of both types of lists have been converted to the new
code, for demonstration purposes. Other uses can (and probably will) be
converted in the future. Since dllist.c is unused after this conversion,
it has been removed.
Author: Andres Freund
Some tweaks by me
Reviewed by Tom Lane, Peter Geoghegan
