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Simplify and rename some GUC variables, per various recent discussions:

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* 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.
This commit is contained in:
Tom Lane
2007-09-24 03:12:23 +00:00
parent 02138357ff
commit 48f7e64395
14 changed files with 182 additions and 351 deletions
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48
doc/src/sgml/monitoring.sgml
View File

@@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/monitoring.sgml,v 1.52 2007/09/20 17:56:30 tgl Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/monitoring.sgml,v 1.53 2007/09/24 03:12:23 tgl Exp $ -->
<chapter id="monitoring">
<title>Monitoring Database Activity</title>
@@ -117,14 +117,15 @@ postgres: <replaceable>user</> <replaceable>database</> <replaceable>host</> <re
<productname>PostgreSQL</productname>'s <firstterm>statistics collector</>
is a subsystem that supports collection and reporting of information about
server activity. Presently, the collector can count accesses to tables
and indexes in both disk-block and individual-row terms.
and indexes in both disk-block and individual-row terms. It also tracks
total numbers of rows in each table, and the last vacuum and analyze times
for each table.
</para>
<para>
<productname>PostgreSQL</productname> also supports determining the exact
command currently being executed by other server processes. This is an
independent facility that can be enabled or disabled whether or not
block-level and row-level statistics are being collected.
independent facility that does not depend on the collector process.
</para>
<sect2 id="monitoring-stats-setup">
@@ -139,31 +140,14 @@ postgres: <replaceable>user</> <replaceable>database</> <replaceable>host</> <re
</para>
<para>
The parameter <xref linkend="guc-stats-start-collector"> must be
set to <literal>true</> for the statistics collector to be launched
at all. This is the default and recommended setting, but it can be
turned off if you have no interest in statistics and want to
squeeze out every last drop of overhead. (The savings is likely to
be small, however.) Note that this option cannot be changed while
the server is running.
The parameter <xref linkend="guc-track-counts"> controls whether
information is actually sent to the collector process and thus determines
whether any run-time overhead occurs for event counting.
</para>
<para>
The parameters <xref linkend="guc-stats-block-level"> and <xref
linkend="guc-stats-row-level"> control how much information is
actually sent to the collector and thus determine how much run-time
overhead occurs. These respectively determine whether a server
process tracks disk-block-level access
statistics and row-level access statistics and sends these to the collector.
Additionally, per-database transaction commit and abort statistics
are collected if either of these parameters are set.
</para>
<para>
The parameter <xref linkend="guc-stats-command-string"> enables monitoring
The parameter <xref linkend="guc-track-activities"> enables monitoring
of the current command being executed by any server process.
The statistics collector subprocess need not be running to enable this
feature.
</para>
<para>
@@ -190,13 +174,13 @@ postgres: <replaceable>user</> <replaceable>database</> <replaceable>host</> <re
<para>
When using the statistics to monitor current activity, it is important
to realize that the information does not update instantaneously.
Each individual server process transmits new block and row access counts to
Each individual server process transmits new statistical counts to
the collector just before going idle; so a query or transaction still in
progress does not affect the displayed totals. Also, the collector itself
emits a new report at most once per <varname>PGSTAT_STAT_INTERVAL</varname>
milliseconds (500 unless altered while building the server). So the
displayed information lags behind actual activity. However, current-query
information collected by <varname>stats_command_string</varname> is
information collected by <varname>track_activities</varname> is
always up-to-date.
</para>
@@ -240,7 +224,7 @@ postgres: <replaceable>user</> <replaceable>database</> <replaceable>host</> <re
current query began execution, time at which the process was
started, and client's address and port number. The columns that
report data on the current query are available unless the parameter
<varname>stats_command_string</varname> has been turned off.
<varname>track_activities</varname> has been turned off.
Furthermore, these columns are only visible if the user examining
the view is a superuser or the same as the user owning the process
being reported on.
@@ -715,7 +699,7 @@ postgres: <replaceable>user</> <replaceable>database</> <replaceable>host</> <re
Active command of the given server process, but only if the
current user is a superuser or the same user as that of
the session being queried (and
<varname>stats_command_string</varname> is on)
<varname>track_activities</varname> is on)
</entry>
</row>
@@ -726,7 +710,7 @@ postgres: <replaceable>user</> <replaceable>database</> <replaceable>host</> <re
True if the given server process is waiting for a lock,
but only if the current user is a superuser or the same user as that of
the session being queried (and
<varname>stats_command_string</varname> is on)
<varname>track_activities</varname> is on)
</entry>
</row>
@@ -738,7 +722,7 @@ postgres: <replaceable>user</> <replaceable>database</> <replaceable>host</> <re
executing query was started, but only if the
current user is a superuser or the same user as that of
the session being queried (and
<varname>stats_command_string</varname> is on)
<varname>track_activities</varname> is on)
</entry>
</row>
@@ -750,7 +734,7 @@ postgres: <replaceable>user</> <replaceable>database</> <replaceable>host</> <re
executing transaction was started, but only if the
current user is a superuser or the same user as that of
the session being queried (and
<varname>stats_command_string</varname> is on)
<varname>track_activities</varname> is on)
</entry>
</row>