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.
to be initialized with proper values. Affected parameters are
fillfactor, analyze_threshold, and analyze_scale_factor.
Especially uninitialized fillfactor caused inefficient page usage
because we built a StdRdOptions struct in which fillfactor is zero
if any reloption is set for the toast table.
In addition, we disallow toast.autovacuum_analyze_threshold and
toast.autovacuum_analyze_scale_factor because we didn't actually
support them; they are always ignored.
Report by Rumko on pgsql-bugs on 12 May 2010.
Analysis by Tom Lane and Alvaro Herrera. Patch by me.
Backpatch to 8.4.
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.
field of the WAL record. The previous coding always wrote to the main fork,
resulting in data corruption if the page was meant to go into a non-default
fork.
At present, the only operation that can produce such WAL records is
ALTER TABLE/INDEX SET TABLESPACE when executed with archive_mode = on.
Data corruption would be observed on standby slaves, and could occur on the
master as well if a database crash and recovery occurred after committing
the ALTER and before the next checkpoint. Per report from Gordon Shannon.
Back-patch to 8.4; the problem doesn't exist in earlier branches because
we didn't have a concept of multiple relation forks then.
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.
come from the realistion that HEAP2_CLEAN records don't
always remove user visible data, so conflict processing for
them can be skipped. Confirm validity using Assert checks,
clarify circumstances under which we log heap_cleanup_info
records. Tuning arises from bug fixing of earlier safety
check failures.
vacuum_log_cleanup_info() now generates log records with a valid
latestRemovedXid set in all cases. Also be careful not to zero the
value when we do a round of vacuuming part-way through lazy_scan_heap().
Incidentally, this reduces frequency of conflicts in Hot Standby.
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.
Tom Lane
Bruce Momjian
Robert Haas
Heikki Linnakangas
Peter Eisentraut
Itagaki Takahiro
Magnus Hagander
Simon Riggs