This privilege is required to do Streaming Replication, instead of
superuser, making it possible to set up a SR slave that doesn't
have write permissions on the master.
Superuser privileges do NOT override this check, so in order to
use the default superuser account for replication it must be
explicitly granted the REPLICATION permissions. This is backwards
incompatible change, in the interest of higher default security.
cleanup stage to finish incomplete inserts or splits anymore. There was two
reasons for the cleanup step:
1. When a new tuple was inserted to a leaf page, the downlink in the parent
needed to be updated to contain (ie. to be consistent with) the new key.
Updating the parent in turn might require recursively updating the parent of
the parent. We now handle that by updating the parent while traversing down
the tree, so that when we insert the leaf tuple, all the parents are already
consistent with the new key, and the tree is consistent at every step.
2. When a page is split, we need to insert the downlink for the new right
page(s), and update the downlink for the original page to not include keys
that moved to the right page(s). We now handle that by setting a new flag,
F_FOLLOW_RIGHT, on the non-rightmost pages in the split. When that flag is
set, scans always follow the rightlink, regardless of the NSN mechanism used
to detect concurrent page splits. That way the tree is consistent right after
split, even though the downlink is still missing. This is very similar to the
way B-tree splits are handled. When the downlink is inserted in the parent,
the flag is cleared. To keep the insertion algorithm simple, when an
insertion sees an incomplete split, indicated by the F_FOLLOW_RIGHT flag, it
finishes the split before doing anything else.
These changes allow removing the whole "invalid tuple" mechanism, but I
retained the scan code to still follow invalid tuples correctly. While we
don't create any such tuples anymore, we want to handle them gracefully in
case you pg_upgrade a GiST index that has them. If we encounter any on an
insert, though, we just throw an error saying that you need to REINDEX.
The issue that got me into doing this is that if you did a checkpoint while
an insert or split was in progress, and the checkpoint finishes quickly so
that there is no WAL record related to the insert between RedoRecPtr and the
checkpoint record, recovery from that checkpoint would not know to finish
the incomplete insert. IOW, we have the same issue we solved with the
rm_safe_restartpoint mechanism during normal operation too. It's highly
unlikely to happen in practice, and this fix is far too large to backpatch,
so we're just going to live with in previous versions, but this refactoring
fixes it going forward.
With this patch, you don't get the annoying
'index "FOO" needs VACUUM or REINDEX to finish crash recovery' notices
anymore if you crash at an unfortunate moment.
This case can arise if a transaction has written data, but only to
temporary tables. Loss of the commit record in case of a crash won't
matter, because the temporary tables will be lost anyway.
Reviewed by Heikki Linnakangas and Simon Riggs.
Purely cosmetic patch to make our coding standards more consistent ---
we were doing symbolic some places and octal other places. This patch
fixes all C-coded uses of mkdir, chmod, and umask. There might be some
other calls I missed. Inconsistency noted while researching tablespace
directory permissions issue.
First, avoid scanning the whole ProcArray once we know there
are at least commit_siblings active; second, skip the check
altogether if commit_siblings = 0.
Greg Smith
an old transaction running in the master, and a lot of transactions have
started and finished since, and a WAL-record is written in the gap between
the creating the running-xacts snapshot and WAL-logging it, recovery will fail
with "too many KnownAssignedXids" error. This bug was reported by
Joachim Wieland on Nov 19th.
In the same scenario, when fewer transactions have started so that all the
xids fit in KnownAssignedXids despite the first bug, a more serious bug
arises. We incorrectly initialize the clog code with the oldest still running
transaction, and when we see the WAL record belonging to a transaction with
an XID larger than one that committed already before the checkpoint we're
recovering from, we zero the clog page containing the already committed
transaction, leading to data loss.
In hindsight, trying to track xids in the known-assigned-xids array before
seeing the running-xacts record was too complicated. To fix that, hold
XidGenLock while the running-xacts snapshot is taken and WAL-logged. That
ensures that no transaction can begin or end in that gap, so that in recvoery
we know that the snapshot contains all transactions running at that point in
WAL.
This eliminates some crufty, special-purpose code and, as a non-trivial
side benefit, allows recovery.conf parameters to be unquoted.
Dimitri Fontaine, with review and cleanup by Alvaro Herrera, Itagaki
Takahiro, and me.
location read from backup label file can be found: wasShutdown was set
incorrectly when a backup label file was found.
Jeff Davis, with a little tweaking by me.
rather than 0/0, so that we can safely use 0/0 as an invalid value. This is a
more future-proof fix for the corner-case bug in streaming replication that
was fixed yesterday. We had a similar corner-case bug with log/seg 0/0 back in
February as well. Avoiding 0/0 as a valid value should prevent bugs like that
in the future. Per Tom Lane's idea.
Back-patch to 9.0. Since this only affects bootstrapping, it makes no
difference to existing installations. We don't need to worry about the
bug in existing installations, because if you've managed to get past the
initial base backup already, you won't hit the bug in the future either.
streaming replication. We used log/seg 0/0 to indicate that no WAL segments
have been removed since startup, but 0/0 is a valid value for the very first
WAL segment after initdb. To make that disambiguous, store
(latest removed WAL segment + 1) in the global variable.
Per report from Matt Chesler, also reproduced by Greg Smith.
that WAL file containing the checkpoint redo-location can be found. This
avoids making the cluster irrecoverable if the redo location is in an earlie
WAL file than the checkpoint record.
Report, analysis and patch by Jeff Davis, with small changes by me.
outside a transaction.
This repairs brain fade in my patch of 2009-08-30: the reason we had been
storing oldest-database name, not OID, in ShmemVariableCache was of course
to avoid having to do a catalog lookup at times when it might be unsafe.
This error explains why Aleksandr Dushein is having trouble getting out of
an XID wraparound state in bug #5718, though not how he got into that state
in the first place. I suspect pg_upgrade is at fault there.
This call was present in the aboriginal code from Berkeley, and has
never been touched; it may very well be that it was there to mask
effects of bugs in other places and it may no longer be necessary.
The removal has been foreseen in a code comment since 2007; this seems
to be a good time to test this hypothesis.
new WAL arrives via streaming replication. This reduces the latency, and
also allows us to use a longer polling interval, which is good for energy
efficiency.
We still need to poll to check for the appearance of a trigger file, but
the interval is now 5 seconds (instead of 100ms), like when waiting for
a new WAL segment to appear in WAL archive.
wait until it is set. Latches can be used to reliably wait until a signal
arrives, which is hard otherwise because signals don't interrupt select()
on some platforms, and even when they do, there's race conditions.
On Unix, latches use the so called self-pipe trick under the covers to
implement the sleep until the latch is set, without race conditions. On
Windows, Windows events are used.
Use the new latch abstraction to sleep in walsender, so that as soon as
a transaction finishes, walsender is woken up to immediately send the WAL
to the standby. This reduces the latency between master and standby, which
is good.
Preliminary work by Fujii Masao. The latch implementation is by me, with
helpful comments from many people.
initialize the rd_backend field of a fake Relation entry correctly.
Fortunately, that is easy, since only non-temp relations should ever be
mentioned in the WAL stream.
This allows us to reliably remove all leftover temporary relation
files on cluster startup without reference to system catalogs or WAL;
therefore, we no longer include temporary relations in XLOG_XACT_COMMIT
and XLOG_XACT_ABORT WAL records.
Since these changes require including a backend ID in each
SharedInvalSmgrMsg, the size of the SharedInvalidationMessage.id
field has been reduced from two bytes to one, and the maximum number
of connections has been reduced from INT_MAX / 4 to 2^23-1. It would
be possible to remove these restrictions by increasing the size of
SharedInvalidationMessage by 4 bytes, but right now that doesn't seem
like a good trade-off.
Review by Jaime Casanova and Tom Lane.
Since the only purpose of WAL-loggin SharedInvalidationMessages is to support
Hot Standby operation, they needn't be included when wal_level < hot_standby.
Back-patch to 9.0.
Review by Heikki Linnakanagas and Fujii Masao.
Transaction aborts now record their LSN to avoid corner case
behaviour in SR/HS, hence change of name of variables and functions.
As pointed out by Fujii Masao. Cosmetic changes only.
idea from the start since the variable is only meant to track commit/abort
events. This patch reverts the logic around the variable to what it was in
8.4, except that the value is now kept in shared memory rather than a static
variable, so that it can be reported correctly by CreateRestartPoint (which is
executed in the bgwriter).
max_standby_streaming_delay, and revise the implementation to avoid assuming
that timestamps found in WAL records can meaningfully be compared to clock
time on the standby server. Instead, the delay limits are compared to the
elapsed time since we last obtained a new WAL segment from archive or since
we were last "caught up" to WAL data arriving via streaming replication.
This avoids problems with clock skew between primary and standby, as well
as other corner cases that the original coding would misbehave in, such
as the primary server having significant idle time between transactions.
Per my complaint some time ago and considerable ensuing discussion.
Do some desultory editing on the hot standby documentation, too.
master. Otherwise a subsequent crash could cause the master to lose WAL that
has already been applied on the slave, resulting in the slave being out of
sync and soon corrupt. Per recent discussion and an example from Robert Haas.
Fujii Masao
and retry. If the record is genuinely corrupt in the master database,
there's little hope of recovering, but it's better than simply retrying
to apply the corrupt WAL record in a tight loop without even trying to
retransmit it, which is what we used to do.
pg_last_xlog_replay_location(). Per Robert Haas's suggestion, after
Itagaki Takahiro pointed out an issue in the docs. Also, some wording
changes in the docs by me.
checkpoint_timeout to trigger restartpoints. We used to deliberately only
do time-based restartpoints, because if checkpoint_segments is small we
would spend time doing restartpoints more often than really necessary.
But now that restartpoints are done in bgwriter, they're not as
disruptive as they used to be. Secondly, because streaming replication
stores the streamed WAL files in pg_xlog, we want to clean it up more
often to avoid running out of disk space when checkpoint_timeout is large
and checkpoint_segments small.
Patch by Fujii Masao, with some minor changes by me.
the current one. Not doing this would leave the walwriter with a handle to a
deleted file if there was nothing for it to do for a long period of time,
preventing the file from being completely removed.
Reported by Tollef Fog Heen, and thanks to Heikki for some hand-holding with
the patch.
so simply leads to data waiting in wal_buffers which then causes
later commits to potentially do emergency writes and for all forms
of replication to be potentially delayed without need or benefit.
Issue pointed out exactly by Fujii Masao, following bug report
by Robert Haas on a separate though related topic.
of requirements and documentation on LogStandbySnapshot(). Fixes
two minor bugs reported by Tom Lane that would lead to an incorrect
snapshot after transaction wraparound. Also fix two other problems
discovered that would give incorrect snapshots in certain cases.
ProcArrayApplyRecoveryInfo() substantially rewritten. Some minor
refactoring of xact_redo_apply() and ExpireTreeKnownAssignedTransactionIds().
minRecoveryPoint in control file when replaying a parameter change record,
to ensure that we don't allow hot standby on WAL generated without
wal_level='hot_standby' after a standby restart.
MaxStandbyDelay. Use the GUC units mechanism for the value, and choose more
appropriate timestamp functions for performing tests with it. Make the
ps_activity manipulation in ResolveRecoveryConflictWithVirtualXIDs have
behavior similar to ps_activity code elsewhere, notably not updating the
display when update_process_title is off and not truncating the display
contents at an arbitrarily-chosen length. Improve the docs to be explicit
about what MaxStandbyDelay actually measures, viz the difference between
primary and standby servers' clocks, and the possible hazards if their clocks
aren't in sync.
to perform a backup without archive_mode being enabled. This gives up some
user-error protection in order to improve usefulness for streaming-replication
scenarios. Per discussion.
confusion with streaming-replication settings. Also, change its default
value to "off", because of concern about executing new and poorly-tested
code during ordinary non-replicating operation. Per discussion.
In passing do some minor editing of related documentation.
rather than returning NULL for some-but-not-all failures as they used to.
Remove now-redundant tests for NULL from call sites.
We had to do something about this because many call sites were failing to
check for NULL; and changing it like this seems a lot more useful and
mistake-proof than adding checks to the call sites without them.
archival or hot standby should be WAL-logged, instead of deducing that from
other options like archive_mode. This replaces recovery_connections GUC in
the primary, where it now has no effect, but it's still used in the standby
to enable/disable hot standby.
Remove the WAL-logging of "unlogged operations", like creating an index
without WAL-logging and fsyncing it at the end. Instead, we keep a copy of
the wal_mode setting and the settings that affect how much shared memory a
hot standby server needs to track master transactions (max_connections,
max_prepared_xacts, max_locks_per_xact) in pg_control. Whenever the settings
change, at server restart, write a WAL record noting the new settings and
update pg_control. This allows us to notice the change in those settings in
the standby at the right moment, they used to be included in checkpoint
records, but that meant that a changed value was not reflected in the
standby until the first checkpoint after the change.
Bump PG_CONTROL_VERSION and XLOG_PAGE_MAGIC. Whack XLOG_PAGE_MAGIC back to
the sequence it used to follow, before hot standby and subsequent patches
changed it to 0x9003.
and be more tense about the locking requirements for it, to improve performance
in Hot Standby mode. In passing fix a few bugs and improve a number of
comments in the existing HS code.
Simon Riggs, with some editorialization by Tom
in WAL recovery when it sees the shutdown checkpoint record. It's more
user-friendly to find out about it at that point than at the end of
recovery, and you're not left wondering why your hot standby server never
opens up for read-only connections.
of parameters. Fix bug report by Robert Haas that error message and
hint was incorrect if wrong mode parameters specified on master.
Internal changes only. Proposals for parameter simplification on
master/primary still under way.
Also, make the name of the GUC and the name of the backing variable match.
Alnong the way, clean up a couple of slight typographical errors in the
related docs.
Now doesn't report it is waiting until it actually is waiting,
plus message doesn't appear until at least 5 seconds wait, so
we avoid reporting the wait before we've given the archiver
a reasonable time to wake up and archive the file we just
created earlier in the function.
Also add new unconditional message to confirm safe completion.
Now a normal, healthy execution does not report waiting at
all, just safe completion.
through normal backends. Makes code clearer also, since we
avoid various Assert()s. Performance of snapshots taken
during recovery no longer depends upon number of read-only
backends.
after actually removing one, so that if we can't remove segments because
WAL archiving is lagging behind, we don't unnecessarily forbid streaming
the old not-yet-archived segments that are still perfectly valid. Per
suggestion from Fujii Masao.
doesn't take into account how far the WAL senders are. This way a hung
WAL sender doesn't prevent old WAL segments from being recycled/removed
in the primary, ultimately causing the disk to fill up. Instead add
standby_keep_segments setting to control how many old WAL segments are
kept in the primary. This also makes it more reliable to use streaming
replication without WAL archiving, assuming that you set
standby_keep_segments high enough.
recovery. We might want to relax this in the future, but ThisTimeLineID
isn't currently correct in backends during recovery, so the filename
returned was wrong.
This allows us to see what mode the server is in before it starts to
perform actions that can block or hang. Otherwise server messages
may not appear until after messages that say FATAL the database
server is starting up.
The error message now makes explicit reference to the GUC that must be changed
to fix the problem, using wording suggested by Tom Lane. Along the way,
rename the GUC from MaxWalSenders to max_wal_senders for consistency and
grep-ability.
pg_xlog directory. This is essential for replaying WAL records that
were streamed from the master, after a standby server restart.
If a corrupt record is seen in a file restored from the archive or
streamed from the master, log it as a WARNING and keep retrying. If the
corruption is permanent, and not just a glitch in the whatever copies the
files to the archive or a network error not caught by CRC checks in TCP
for example, we will keep retrying and logging the WARNING indefinitely.
But that's better than shutting down completely, the standby is still
useful for running read-only queries. In PITR the recovery ends at such a
corrupt record, which is a bit questionable, but that's the behavior we
had in previous releases and we don't feel like chaning it now. It does
make sense for tools like pg_standby.
example to 'on or 'off' rather than 'true' or 'false', as shown
in docs. Add restartpoint_command. Add section header for recovery
target parameters, matching docs.
present since 8.0 was never fully meaningful, since two recovery targets
cannot be specified. Refactor recovery target type to make this change
and associated code easier to understand. No change in function.
Bug report arising from internal support question.
in recovery_end_command, it always came out as 0 because InRedo was
cleared before recovery_end_command was executed. Also, always take
ControlFileLock when reading checkpoint location for %r.
The recovery_end_command bug and the missing locking was present in 8.4
as well, that part of this patch will be backported separately.
instead of an exclusive lock.
The change is almost for code cleanup. Since there seems to be no
performance benefits from it, backports should not be needed.
Fujii Masao
Add some checks that seem logically necessary, in particular let's make
real sure that HS slave sessions cannot create temp tables. (If they did
they would think that temp tables belonging to the master's session with
the same BackendId were theirs. We *must* not allow myTempNamespace to
become set in a slave session.)
Change setval() and nextval() so that they are only allowed on temp sequences
in a read-only transaction. This seems consistent with what we allow for
table modifications in read-only transactions. Since an HS slave can't have a
temp sequence, this also provides a nicer cure for the setval PANIC reported
by Erik Rijkers.
Make the error messages more uniform, and have them mention the specific
command being complained of. This seems worth the trifling amount of extra
code, since people are likely to see such messages a lot more than before.
enabled. Bypassing the kernel cache is counter-productive in that case,
because the archiver/walsender process will read from the WAL file
soon after it's written, and if it's not cached the read will cause
a physical read, eating I/O bandwidth available on the WAL drive.
Also, walreceiver process does unaligned writes, so disable O_DIRECT
in walreceiver process for that reason too.
segment of XLOG_BACKUP_END record even if the the record is placed
at a segment boundary. Furthermore the previous implementation could
return nonexistent segment file name when the boundary is in segments
that has "FE" suffix; We never use segments with "FF" suffix.
Backpatch to 8.0, where hot backup was introduced.
Reported by Fujii Masao.
Magnus Hagander
Bruce Momjian
Heikki Linnakangas
Robert Haas
Tom Lane
Simon Riggs
Peter Eisentraut
Alvaro Herrera
Itagaki Takahiro