Previously, only VACUUM would cause a page range to get initially
summarized by BRIN indexes, which for some use cases takes too much time
since the inserts occur. To avoid the delay, have brininsert request a
summarization run for the previous range as soon as the first tuple is
inserted into the first page of the next range. Autovacuum is in charge
of processing these requests, after doing all the regular vacuuming/
analyzing work on tables.
This doesn't impose any new tasks on autovacuum, because autovacuum was
already in charge of doing summarizations. The only actual effect is to
change the timing, i.e. that it occurs earlier. For this reason, we
don't go any great lengths to record these requests very robustly; if
they are lost because of a server crash or restart, they will happen at
a later time anyway.
Most of the new code here is in autovacuum, which can now be told about
"work items" to process. This can be used for other things such as GIN
pending list cleaning, perhaps visibility map bit setting, both of which
are currently invoked during vacuum, but do not really depend on vacuum
taking place.
The requests are at the page range level, a granularity for which we did
not have SQL-level access; we only had index-level summarization
requests via brin_summarize_new_values(). It seems reasonable to add
SQL-level access to range-level summarization too, so add a function
brin_summarize_range() to do that.
Authors: Álvaro Herrera, based on sketch from Simon Riggs.
Reviewed-by: Thomas Munro.
Discussion: https://postgr.es/m/20170301045823.vneqdqkmsd4as4ds@alvherre.pgsql
This improves on commit bbfd7edae5 by
making two simple changes:
* pg_attribute_noreturn now takes parentheses, ie pg_attribute_noreturn().
Likewise pg_attribute_unused(), pg_attribute_packed(). This reduces
pgindent's tendency to misformat declarations involving them.
* attributes are now always attached to function declarations, not
definitions. Previously some places were taking creative shortcuts,
which were not merely candidates for bad misformatting by pgindent
but often were outright wrong anyway. (It does little good to put a
noreturn annotation where callers can't see it.) In any case, if
we would like to believe that these macros can be used with non-gcc
compilers, we should avoid gratuitous variance in usage patterns.
I also went through and manually improved the formatting of a lot of
declarations, and got rid of excessively repetitive (and now obsolete
anyway) comments informing the reader what pg_attribute_printf is for.
Until now __attribute__() was defined to be empty for all compilers but
gcc. That's problematic because it prevents using it in other compilers;
which is necessary e.g. for atomics portability. It's also just
generally dubious to do so in a header as widely included as c.h.
Instead add pg_attribute_format_arg, pg_attribute_printf,
pg_attribute_noreturn macros which are implemented in the compilers that
understand them. Also add pg_attribute_noreturn and pg_attribute_packed,
but don't provide fallbacks, since they can affect functionality.
This means that external code that, possibly unwittingly, relied on
__attribute__ defined to be empty on !gcc compilers may now run into
warnings or errors on those compilers. But there shouldn't be many
occurances of that and it's hard to work around...
Discussion: 54B58BA3.8040302@ohmu.fi
Author: Oskari Saarenmaa, with some minor changes by me.
Previously we were piggybacking on transaction ID parameters to freeze
multixacts; but since there isn't necessarily any relationship between
rates of Xid and multixact consumption, this turns out not to be a good
idea.
Therefore, we now have multixact-specific freezing parameters:
vacuum_multixact_freeze_min_age: when to remove multis as we come across
them in vacuum (default to 5 million, i.e. early in comparison to Xid's
default of 50 million)
vacuum_multixact_freeze_table_age: when to force whole-table scans
instead of scanning only the pages marked as not all visible in
visibility map (default to 150 million, same as for Xids). Whichever of
both which reaches the 150 million mark earlier will cause a whole-table
scan.
autovacuum_multixact_freeze_max_age: when for cause emergency,
uninterruptible whole-table scans (default to 400 million, double as
that for Xids). This means there shouldn't be more frequent emergency
vacuuming than previously, unless multixacts are being used very
rapidly.
Backpatch to 9.3 where multixacts were made to persist enough to require
freezing. To avoid an ABI break in 9.3, VacuumStmt has a couple of
fields in an unnatural place, and StdRdOptions is split in two so that
the newly added fields can go at the end.
Patch by me, reviewed by Robert Haas, with additional input from Andres
Freund and Tom Lane.
There was a wild mix of calling conventions: Some were declared to
return void and didn't return, some returned an int exit code, some
claimed to return an exit code, which the callers checked, but
actually never returned, and so on.
Now all of these functions are declared to return void and decorated
with attribute noreturn and don't return. That's easiest, and most
code already worked that way.
via the "flat files" facility. This requires making it enough like a backend
to be able to run transactions; it's no longer an "auxiliary process" but
more like the autovacuum worker processes. Also, its signal handling has
to be brought into line with backends/workers. In particular, since it
now has to handle procsignal.c processing, the special autovac-launcher-only
signal conditions are moved to SIGUSR2.
Alvaro, with some cleanup from Tom
* stats_start_collector goes away; we always start the collector process,
unless prevented by a problem with setting up the stats UDP socket.
* stats_reset_on_server_start goes away; it seems useless in view of the
availability of pg_stat_reset().
* stats_block_level and stats_row_level are merged into a single variable
"track_counts", which controls all reports sent to the collector process.
* stats_command_string is renamed to track_activities.
* log_autovacuum is renamed to log_autovacuum_min_duration to better reflect
its meaning.
The log_autovacuum change is not a compatibility issue since it didn't exist
before 8.3 anyway. The other changes need to be release-noted.
by having the postmaster signal it when certain failures occur. This requires
the postmaster setting a flag in shared memory, but should be as safe as the
pmsignal.c code is.
Also make sure the launcher honor's a postgresql.conf change turning it off
on SIGHUP.
processes to be running simultaneously. Also, now autovacuum processes do not
count towards the max_connections limit; they are counted separately from
regular processes, and are limited by the new GUC variable
autovacuum_max_workers.
The launcher now has intelligence to launch workers on each database every
autovacuum_naptime seconds, limited only on the max amount of worker slots
available.
Also, the global worker I/O utilization is limited by the vacuum cost-based
delay feature. Workers are "balanced" so that the total I/O consumption does
not exceed the established limit. This part of the patch was contributed by
ITAGAKI Takahiro.
Per discussion.
continuously, and requests vacuum runs of "autovacuum workers" to postmaster.
The workers do the actual vacuum work. This allows for future improvements,
like allowing multiple autovacuum jobs running in parallel.
For now, the code keeps the original behavior of having a single autovac
process at any time by sleeping until the previous worker has finished.
accessing it, like DROP DATABASE. This allows the regression tests to pass
with autovacuum enabled, which open the gates for finally enabling autovacuum
by default.
in PITR scenarios. We now WAL-log the replacement of old XIDs with
FrozenTransactionId, so that such replacement is guaranteed to propagate to
PITR slave databases. Also, rather than relying on hint-bit updates to be
preserved, pg_clog is not truncated until all instances of an XID are known to
have been replaced by FrozenTransactionId. Add new GUC variables and
pg_autovacuum columns to allow management of the freezing policy, so that
users can trade off the size of pg_clog against the amount of freezing work
done. Revise the already-existing code that forces autovacuum of tables
approaching the wraparound point to make it more bulletproof; also, revise the
autovacuum logic so that anti-wraparound vacuuming is done per-table rather
than per-database. initdb forced because of changes in pg_class, pg_database,
and pg_autovacuum catalogs. Heikki Linnakangas, Simon Riggs, and Tom Lane.
delay and limit, both as global GUCs and as table-specific entries in
pg_autovacuum. stats_reset_on_server_start is now OFF by default,
but a reset is forced if we did WAL replay. XID-wrap vacuums do not
ANALYZE, but do FREEZE if it's a template database. Alvaro Herrera
Peter Eisentraut
Alvaro Herrera
Bruce Momjian
Tom Lane
Andres Freund
Simon Riggs
Magnus Hagander