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.
Normal superuser processes are allowed to connect even when the database
system is shutting down, or when fewer than superuser_reserved_connection
slots remain. This is intended to make sure an administrator can log in
and troubleshoot, so don't extend these same courtesies to users connecting
for replication.
than during define_custom_variable(). This entails rejecting an ALTER
command if the target variable doesn't have a known (non-placeholder)
definition, unless the calling user is superuser. When the variable *is*
known, we can correctly apply the rule that only superusers can issue ALTER
for SUSET parameters. This allows define_custom_variable to apply ALTER's
values for SUSET parameters at module load time, secure in the knowledge
that only a superuser could have set the ALTER value. This change fixes a
longstanding gotcha in the usage of SUSET-level custom parameters; which
is a good thing to fix now that plpgsql defines such a parameter.
with database = replication. The previous coding would allow them to match
ordinary records too, but that seems like a recipe for security breaches.
Improve the messages associated with no-such-pg_hba.conf entry to report
replication connections as such, since that's now a critical aspect of
whether the connection matches. Make some cursory improvements in the related
documentation, too.
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.
In 8.4 and prior, WAL-logging could potentially be skipped whenever
archive_mode=off. With streaming replication, this is now true only
if max_wal_senders=0.
Fujii Masao, with light copyediting by me
The logic for determining whether to materialize has been significantly
overhauled for 9.0. In case there should be any doubt about whether
materialization is a win in any particular case, this should provide a
convenient way of seeing what happens without it; but even with enable_material
turned off, we still materialize in cases where it is required for
correctness.
Thanks to Tom Lane for the review.
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.
At present, killing the startup process does not release any locks it holds,
so we must wait to stop the startup and walreceiver processes until all
read-only backends have exited. Without this patch, the startup and
walreceiver processes never exit, so the server gets permanently stuck in
a half-shutdown state.
Fujii Masao, with review, docs, and comment adjustments by me.
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.
is changed to match the hard-wired default. This avoids accumulating useless
catalog entries, and also provides a path for dropping the owning role without
using DROP OWNED BY. Per yesterday's complaint from Jaime Casanova, the
need to use DROP OWNED BY for that is less than obvious, so providing this
alternative method might save some user frustration.
The endterm attribute is mainly useful when the toolchain does not support
automatic link target text generation for a particular situation. In the
past, this was required by the man page tools for all reference page links,
but that is no longer the case, and it now actually gets in the way of
proper automatic link text generation. The only remaining use cases are
currently xrefs to refsects.
loop in standby mode, trying to restore from archive, pg_xlog and
streaming.
Move sections around to make the high availability chapter more
coherent: the most prominent part is now a "Log-Shipping Standby Servers"
section that describes what a standby server is (like the old
"Warm Standby Servers for High Availability" section), and how to
set up a warm standby server, including streaming replication, using the
built-in standby mode. The pg_standby method is desribed in another
section called "Alternative method for log shipping", with the added
caveat that it doesn't work with streaming replication.
Tom Lane