</para>
<para>
- The parameter <xref linkend="guc-track-counts"> controls whether
- statistics are collected about table and index accesses.
+ The parameter <xref linkend="guc-track-activities"> enables monitoring
+ of the current command being executed by any server process.
</para>
<para>
- The parameter <xref linkend="guc-track-iotiming"> enables monitoring
- of block read and write times.
+ The parameter <xref linkend="guc-track-counts"> controls whether
+ statistics are collected about table and index accesses.
</para>
<para>
</para>
<para>
- The parameter <xref linkend="guc-track-activities"> enables monitoring
- of the current command being executed by any server process.
+ The parameter <xref linkend="guc-track-iotiming"> enables monitoring
+ of block read and write times.
</para>
<para>
</para>
<para>
- The statistics collector transmits the collected
- information to backends (including autovacuum) through temporary files.
- These files are stored in the <filename>pg_stat_tmp</filename> subdirectory.
- When the postmaster shuts down, a permanent copy of the statistics
- data is stored in the <filename>global</filename> subdirectory. For increased
- performance, the parameter <xref linkend="guc-stats-temp-directory"> can
- be pointed at a RAM-based file system, decreasing physical I/O requirements.
+ The statistics collector transmits the collected information to other
+ <productname>PostgreSQL</productname> processes through temporary files.
+ These files are stored in the directory named by the
+ <xref linkend="guc-stats-temp-directory"> parameter,
+ <filename>pg_stat_tmp</filename> by default.
+ For better performance, <varname>stats_temp_directory</> can be
+ pointed at a RAM-based file system, decreasing physical I/O requirements.
+ When the server shuts down, a permanent copy of the statistics
+ data is stored in the <filename>global</filename> subdirectory, so that
+ statistics can be retained across server restarts.
</para>
</sect2>
Several predefined views, listed in <xref
linkend="monitoring-stats-views-table">, are available to show the results
of statistics collection. Alternatively, one can
- build custom views using the underlying statistics functions.
+ build custom views using the underlying statistics functions, as discussed
+ in <xref linkend="monitoring-stats-functions">.
</para>
<para>
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
+ milliseconds (500 msec unless altered while building the server). So the
displayed information lags behind actual activity. However, current-query
information collected by <varname>track_activities</varname> is
always up-to-date.
collector) in the views <structname>pg_stat_xact_all_tables</>,
<structname>pg_stat_xact_sys_tables</>,
<structname>pg_stat_xact_user_tables</>, and
- <structname>pg_stat_xact_user_functions</>, or via these views' underlying
- functions (named the same as the standard statistics functions but with the
- prefix <function>pg_stat_get_xact_</function>). These numbers do not act
- as stated above; instead they update continuously throughout the transaction.
+ <structname>pg_stat_xact_user_functions</>. These numbers do not act as
+ stated above; instead they update continuously throughout the transaction.
</para>
<table id="monitoring-stats-views-table">
<indexterm><primary>pg_stat_activity</primary></indexterm>
</entry>
<entry>
- <para>One row per server process, showing information related to
- each connection to the server. Unless the
- <xref linkend="guc-track-activities"> parameter has been turned
- off, it is possible to monitor state and query information of
- all running processes.
- </para>
- <para>
- See <xref linkend="pg-stat-activity-view"> for more details.
- </para>
- </entry>
+ One row per server process, showing information related to
+ the current activity of that process, such as state and current query.
+ See <xref linkend="pg-stat-activity-view"> for details.
+ </entry>
</row>
<row>
<entry><structname>pg_stat_bgwriter</><indexterm><primary>pg_stat_bgwriter</primary></indexterm></entry>
- <entry>One row only, showing cluster-wide statistics. See
- <xref linkend="pg-stat-bgwriter-view"> for more details.
+ <entry>One row only, showing statistics about the
+ background writer process's activity. See
+ <xref linkend="pg-stat-bgwriter-view"> for details.
</entry>
</row>
<row>
<entry><structname>pg_stat_database</><indexterm><primary>pg_stat_database</primary></indexterm></entry>
<entry>One row per database, showing database-wide statistics. See
- <xref linkend="pg-stat-database-view"> for more details.
+ <xref linkend="pg-stat-database-view"> for details.
</entry>
</row>
- <row>
- <entry><structname>pg_stat_database_conflicts</><indexterm><primary>pg_stat_database_conflicts</primary></indexterm></entry>
- <entry>
- One row per database showing database-wide statistics about
- query cancels due to conflict with recovery on standby servers.
- Will only contain information on standby servers, since
- conflicts do not occur on master servers.
- See <xref linkend="pg-stat-database-conflicts-view"> for more details.
- </entry>
- </row>
-
- <row>
- <entry><structname>pg_stat_replication</><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
- <entry>One row per WAL sender process, showing statistics about the
- replication to this slave. See <xref linkend="pg-stat-replication-view">
- for more details. Only directly connected standbys are listed; no
- information about downstream standby servers is recorded.
- </entry>
- </row>
-
<row>
<entry><structname>pg_stat_all_tables</><indexterm><primary>pg_stat_all_tables</primary></indexterm></entry>
<entry>
- One row for each table in the current database (including TOAST
- tables) with information about accesses to this specific table.
- See <xref linkend="pg-stat-all-tables-view"> for more details.
+ One row for each table in the current database, showing statistics
+ about accesses to that specific table.
+ See <xref linkend="pg-stat-all-tables-view"> for details.
</entry>
</row>
<row>
<entry><structname>pg_stat_all_indexes</><indexterm><primary>pg_stat_all_indexes</primary></indexterm></entry>
<entry>
- One row for each index in the current database with information
- about accesses to this specific index.
- See <xref linkend="pg-stat-all-indexes-view"> for more details.
+ One row for each index in the current database, showing statistics
+ about accesses to that specific index.
+ See <xref linkend="pg-stat-all-indexes-view"> for details.
</entry>
</row>
<row>
<entry><structname>pg_statio_all_tables</><indexterm><primary>pg_statio_all_tables</primary></indexterm></entry>
<entry>
- One row for each table in the current database (including TOAST
- tables) with information about I/O on this specific table.
- See <xref linkend="pg-statio-all-tables-view"> for more details.
+ One row for each table in the current database, showing statistics
+ about I/O on that specific table.
+ See <xref linkend="pg-statio-all-tables-view"> for details.
</entry>
</row>
<row>
<entry><structname>pg_statio_all_indexes</><indexterm><primary>pg_statio_all_indexes</primary></indexterm></entry>
<entry>
- One row for each index in the current database
- with information about I/O on this specific index.
- See <xref linkend="pg-statio-all-indexes-view"> for more details.
+ One row for each index in the current database,
+ showing statistics about I/O on that specific index.
+ See <xref linkend="pg-statio-all-indexes-view"> for details.
</entry>
</row>
<row>
<entry><structname>pg_statio_all_sequences</><indexterm><primary>pg_statio_all_sequences</primary></indexterm></entry>
<entry>
- One row for each sequence in the current database
- with information about I/O on this specific sequence.
- See <xref linkend="pg-statio-all-sequences-view"> for more details.
+ One row for each sequence in the current database,
+ showing statistics about I/O on that specific sequence.
+ See <xref linkend="pg-statio-all-sequences-view"> for details.
</entry>
</row>
<row>
<entry><structname>pg_stat_user_functions</><indexterm><primary>pg_stat_user_functions</primary></indexterm></entry>
<entry>
- One row for each tracked function (as specified by the
- <xref linkend="guc-track-functions"> parameter). See
- <xref linkend="pg-stat-user-functions-view"> for more details.
+ One row for each tracked function, showing statistics
+ about executions of that function. See
+ <xref linkend="pg-stat-user-functions-view"> for details.
</entry>
</row>
yet included in <structname>pg_stat_user_functions</>).</entry>
</row>
+ <row>
+ <entry><structname>pg_stat_replication</><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
+ <entry>One row per WAL sender process, showing statistics about
+ replication to that sender's connected standby server.
+ See <xref linkend="pg-stat-replication-view"> for details.
+ </entry>
+ </row>
+
+ <row>
+ <entry><structname>pg_stat_database_conflicts</><indexterm><primary>pg_stat_database_conflicts</primary></indexterm></entry>
+ <entry>
+ One row per database, showing database-wide statistics about
+ query cancels due to conflict with recovery on standby servers.
+ See <xref linkend="pg-stat-database-conflicts-view"> for details.
+ </entry>
+ </row>
+
</tbody>
</tgroup>
</table>
indexes are being used and how effective they are.
</para>
- <para>
- Indexes can be
- used either directly or via <quote>bitmap scans</>. In a bitmap scan
- the output of several indexes can be combined via AND or OR rules;
- so it is difficult to associate individual heap row fetches
- with specific indexes when a bitmap scan is used. Therefore, a bitmap
- scan increments the
- <structname>pg_stat_all_indexes</>.<structfield>idx_tup_read</>
- count(s) for the index(es) it uses, and it increments the
- <structname>pg_stat_all_tables</>.<structfield>idx_tup_fetch</>
- count for the table, but it does not affect
- <structname>pg_stat_all_indexes</>.<structfield>idx_tup_fetch</>.
- </para>
-
- <note>
- <para>
- Before <productname>PostgreSQL</productname> 8.1, the
- <structfield>idx_tup_read</> and <structfield>idx_tup_fetch</> counts
- were essentially always equal. Now they can be different even without
- considering bitmap scans, because <structfield>idx_tup_read</> counts
- index entries retrieved from the index while <structfield>idx_tup_fetch</>
- counts live rows fetched from the table; the latter will be less if any
- dead or not-yet-committed rows are fetched using the index, or if any
- heap fetches are avoided by means of an index-only scan.
- </para>
- </note>
-
<para>
The <structname>pg_statio_</> views are primarily useful to
determine the effectiveness of the buffer cache. When the number
into the kernel's handling of I/O.
</para>
- <para>
- Other ways of looking at the statistics can be set up by writing
- queries that use the same underlying statistics access functions as
- these standard views do. These functions are listed in <xref
- linkend="monitoring-stats-funcs-table">. The per-database access
- functions take a database OID as an argument to identify which
- database to report on. The per-table and per-index functions take
- a table or index OID. The functions for function-call statistics
- take a function OID. (Note that only tables, indexes, and functions
- in the current database can be seen with these functions.) The
- per-server-process access functions take a server process
- number, which ranges from one to the number of currently active
- server processes.
- </para>
-
<table id="pg-stat-activity-view" xreflabel="pg_stat_activity">
<title>pg_stat_activity view</title>
<tbody>
<row>
- <entry>datid</entry>
+ <entry><structfield>datid</></entry>
<entry><type>oid</></entry>
- <entry>The OID of the database the backend is connected to.
+ <entry>OID of the database this backend is connected to.
This value can also be returned by directly calling
the <function>pg_stat_get_backend_dbid</function> function.</entry>
</row>
<row>
- <entry>datname</entry>
+ <entry><structfield>datname</></entry>
<entry><type>name</></entry>
- <entry>The name of the database the backend is connected to.</entry>
+ <entry>Name of the database this backend is connected to</entry>
</row>
<row>
- <entry>pid</entry>
+ <entry><structfield>pid</></entry>
<entry><type>integer</></entry>
- <entry>The process ID of the backend.
+ <entry>Process ID of this backend.
This value can also be returned by directly calling
the <function>pg_stat_get_backend_pid</function>.</entry>
</row>
<row>
- <entry>usesysid</entry>
+ <entry><structfield>usesysid</></entry>
<entry><type>oid</></entry>
- <entry>The id of the user logged into the backend.
+ <entry>OID of the user logged into this backend.
This value can also be returned by directly calling
the <function>pg_stat_get_backend_userid</function>.</entry>
</row>
<row>
- <entry>usename</entry>
+ <entry><structfield>usename</></entry>
<entry><type>name</></entry>
- <entry>The name of the user logged into the backend.</entry>
+ <entry>Name of the user logged into this backend</entry>
</row>
<row>
- <entry>application_name</entry>
+ <entry><structfield>application_name</></entry>
<entry><type>text</></entry>
- <entry>The name of the application that has initiated the connection
- to the backend.</entry>
+ <entry>Name of the application that is connected
+ to this backend</entry>
</row>
<row>
- <entry>client_addr</entry>
+ <entry><structfield>client_addr</></entry>
<entry><type>inet</></entry>
- <entry>The remote IP of the client connected to the backend.
- If this field is not set, it indicates that the client is either connected
- via a Unix socket on the server machine or is an internal process such
- as autovacuum.
+ <entry>IP address of the client connected to this backend.
+ If this field is not set, it indicates either that the client is
+ connected via a Unix socket on the server machine or that this is an
+ internal process such as autovacuum.
This value can also be returned by directly calling
the <function>pg_stat_get_backend_client_addr</function>.
</entry>
</row>
<row>
- <entry>client_hostname</entry>
+ <entry><structfield>client_hostname</></entry>
<entry><type>text</></entry>
- <entry>
- If available, the hostname of the client as reported by a
- reverse lookup of <structfield>client_addr</>. This field will
- only be set when <xref linkend="guc-log-hostname"> is enabled.
+ <entry>Host name of the connected client, as reported by a
+ reverse DNS lookup of <structfield>client_addr</>. This field will
+ only be set for IP connections, and only when <xref
+ linkend="guc-log-hostname"> is enabled.
</entry>
</row>
<row>
- <entry>client_port</entry>
+ <entry><structfield>client_port</></entry>
<entry><type>integer</></entry>
- <entry>
- The remote TCP port that the client is using for communication
- to the backend, or <symbol>NULL</> if a unix socket is used.
+ <entry>TCP port number that the client is using for communication
+ with the backend, or <symbol>NULL</> if a Unix socket is used.
This value can also be returned by directly calling
the <function>pg_stat_get_backend_client_port</function>.
</entry>
</row>
<row>
- <entry>backend_start</entry>
+ <entry><structfield>backend_start</></entry>
<entry><type>timestamp with time zone</></entry>
- <entry>
- The time when this process was started, i.e. when the
+ <entry>Time when this process was started, i.e., when the
client connected to the server.
This value can also be returned by directly calling
the <function>pg_stat_get_backend_start</function>.
</entry>
</row>
<row>
- <entry>xact_start</entry>
+ <entry><structfield>xact_start</></entry>
<entry><type>timestamp with time zone</></entry>
- <entry>
- The time when the current transaction was started. If the client is
- using autocommit for transactions, this value is equal to the
- query_start column.
+ <entry>Time when the current transaction was started. If the current
+ query is the first of its transaction, this value is equal to the
+ <structfield>query_start</> column.
This value can also be returned by directly calling
the <function>pg_stat_get_backend_xact_start</function>.
</entry>
</row>
<row>
- <entry>query_start</entry>
+ <entry><structfield>query_start</></entry>
<entry><type>timestamp with time zone</></entry>
- <entry>
- The time when the currently active query started, or if
+ <entry>Time when the currently active query was started, or if
<structfield>state</> is <literal>idle</>, when the last query
was started.
This value can also be returned by directly calling
</entry>
</row>
<row>
- <entry>state_change</entry>
+ <entry><structfield>state_change</></entry>
<entry><type>timestamp with time zone</></entry>
- <entry>The time when the <structfield>state</> was last changed.</entry>
+ <entry>Time when the <structfield>state</> was last changed</entry>
</row>
<row>
- <entry>waiting</entry>
+ <entry><structfield>waiting</></entry>
<entry><type>boolean</></entry>
- <entry>
- Boolean indicating if a backend is currently waiting on a lock.
+ <entry>True if the backend is currently waiting on a lock.
This value can also be returned by directly calling
the <function>pg_stat_get_backend_waiting</function>.
</entry>
</row>
<row>
- <entry>state</entry>
+ <entry><structfield>state</></entry>
<entry><type>text</></entry>
- <entry>
- The <structfield>state</> of the currently running query.
- Can be one of:
- <variablelist>
- <varlistentry>
- <term>active</term>
- <listitem>
- <para>
- The backend is executing a query.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>idle</term>
- <listitem>
- <para>
- There is no query executing in the backend.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>idle in transaction</term>
- <listitem>
- <para>
- The backend is in a transaction, but is currently not currently
- executing a query.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>idle in transaction (aborted)</term>
- <listitem>
- <para>
- This state is similar to <literal>idle in transaction</>,
- except one of the statements in the transaction caused an error.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>fastpath function call</term>
- <listitem>
- <para>
- The backend is executing a fast-path function.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>disabled</term>
- <listitem>
- <para>
- This state indicates that <xref linkend="guc-track-activities">
- is disabled.
- </para>
- </listitem>
- </varlistentry>
- </variablelist>
- <note>
- <para>
- The <structfield>waiting</> and <structfield>state</> columns are
- independent. If a query is in the <literal>active</> state,
- it may or may not be <literal>waiting</>. If a query is
- <literal>active</> and <structfield>waiting</> is true, it means
- that the query is being executed, but is being blocked by a lock
- somewhere in the system.
- </para>
- </note>
+ <entry>Current overall state of this backend.
+ Possible values are:
+ <itemizedlist>
+ <listitem>
+ <para>
+ <literal>active</>: The backend is executing a query.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ <literal>idle</>: The backend is waiting for a new client command.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ <literal>idle in transaction</>: The backend is in a transaction,
+ but is not currently executing a query.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ <literal>idle in transaction (aborted)</>: This state is similar to
+ <literal>idle in transaction</>, except one of the statements in
+ the transaction caused an error.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ <literal>fastpath function call</>: The backend is executing a
+ fast-path function.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ <literal>disabled</>: This state is reported if <xref
+ linkend="guc-track-activities"> is disabled in this backend.
+ </para>
+ </listitem>
+ </itemizedlist>
</entry>
</row>
<row>
- <entry>query</entry>
+ <entry><structfield>query</></entry>
<entry><type>text</></entry>
- <entry>
- The most recent query that the backend has executed. If
- <structfield>state</> is <literal>active</> this means the currently
- executing query. In all other states, it means the last query that was
- executed.
+ <entry>Text of the backend's most recent query. If
+ <structfield>state</> is <literal>active</> this field shows the
+ currently executing query. In all other states, it shows the last query
+ that was executed.
</entry>
</row>
</tbody>
<para>
The <structname>pg_stat_activity</structname> view will have one row
- per server process, showing information related to each connection to
- the server.
+ per server process, showing information related to
+ the current activity of that process.
</para>
- <para>
- All functions used in the view are indexed by backend id number. The
- function <function>pg_stat_get_backend_idset</function> provides a
- convenient way to generate one row for each active server process. For
- example, to show the <acronym>PID</>s and current queries of all server processes:
-<programlisting>
-SELECT pg_stat_get_backend_pid(s.backendid) AS pid,
- pg_stat_get_backend_activity(s.backendid) AS query
- FROM (SELECT pg_stat_get_backend_idset() AS backendid) AS s;
-</programlisting>
- </para>
+ <note>
+ <para>
+ The <structfield>waiting</> and <structfield>state</> columns are
+ independent. If a backend is in the <literal>active</> state,
+ it may or may not be <literal>waiting</>. If the state is
+ <literal>active</> and <structfield>waiting</> is true, it means
+ that a query is being executed, but is being blocked by a lock
+ somewhere in the system.
+ </para>
+ </note>
<table id="pg-stat-bgwriter-view" xreflabel="pg_stat_bgwriter">
<title>pg_stat_bgwriter view</title>
<tbody>
<row>
- <entry>checkpoints_timed</entry>
+ <entry><structfield>checkpoints_timed</></entry>
<entry><type>bigint</type></entry>
- <entry>Number of scheduled checkpoints.
+ <entry>Number of scheduled checkpoints that have been performed.
This value can also be returned by directly calling
the <function>pg_stat_get_bgwriter_timed_checkpoints</function> function.</entry>
</row>
<row>
- <entry>checkpoints_requested</entry>
+ <entry><structfield>checkpoints_req</></entry>
<entry><type>bigint</type></entry>
- <entry>Number of requested checkpoints.
+ <entry>Number of requested checkpoints that have been performed.
This value can also be returned by directly calling
the <function>pg_stat_get_bgwriter_requested_checkpoints</function> function.</entry>
</row>
<row>
- <entry>checkpoint_write_time</entry>
+ <entry><structfield>checkpoint_write_time</></entry>
<entry><type>bigint</type></entry>
<entry>
Total amount of time that has been spent in the portion of
</entry>
</row>
<row>
- <entry>checkpoint_sync_time</entry>
+ <entry><structfield>checkpoint_sync_time</></entry>
<entry><type>bigint</type></entry>
<entry>
Total amount of time that has been spent in the portion of
</entry>
</row>
<row>
- <entry>buffers_checkpoint</entry>
+ <entry><structfield>buffers_checkpoint</></entry>
<entry><type>bigint</type></entry>
<entry>Number of buffers written during checkpoints.
This value can also be returned by directly calling
the <function>pg_stat_get_bgwriter_buf_written_checkpoints</function> function.</entry>
</row>
<row>
- <entry>buffers_clean</entry>
+ <entry><structfield>buffers_clean</></entry>
<entry><type>bigint</type></entry>
<entry>Number of buffers written by the background writer.
This value can also be returned by directly calling
the <function>pg_stat_get_bgwriter_buf_written_clean</function> function.</entry>
</row>
<row>
- <entry>maxwritten_clean</entry>
+ <entry><structfield>maxwritten_clean</></entry>
<entry><type>bigint</type></entry>
<entry>Number of times the background writer stopped a cleaning
scan because it had written too many buffers.
the <function>pg_stat_get_bgwriter_maxwritten_clean</function> function.</entry>
</row>
<row>
- <entry>buffers_backend</entry>
+ <entry><structfield>buffers_backend</></entry>
<entry><type>bigint</type></entry>
<entry>Number of buffers written directly by a backend.
This value can also be returned by directly calling
the <function>pg_stat_get_buf_written_backend</function> function.</entry>
</row>
<row>
- <entry>buffers_backend_fsync</entry>
+ <entry><structfield>buffers_backend_fsync</></entry>
<entry><type>bigint</type></entry>
- <entry>Number of times a backend had to execute its own fsync
- call (normally the background writer handles those even when the
- backend does its own write)</entry>
+ <entry>Number of times a backend had to execute its own
+ <function>fsync</> call (normally the background writer handles those
+ even when the backend does its own write)</entry>
</row>
<row>
- <entry>buffers_alloc</entry>
+ <entry><structfield>buffers_alloc</></entry>
<entry><type>bigint</type></entry>
<entry>Number of buffers allocated.
This value can also be returned by directly calling
the <function>pg_stat_get_buf_alloc</function> function.</entry>
</row>
<row>
- <entry>stats_reset</entry>
- <entry><type>bigint</type></entry>
- <entry>The last time these statistics were reset.
+ <entry><structfield>stats_reset</></entry>
+ <entry><type>timestamp with time zone</type></entry>
+ <entry>Time at which these statistics were last reset.
This value can also be returned by directly calling
the <function>pg_stat_get_bgwriter_stat_reset_time</function> function.</entry>
</row>
<para>
The <structname>pg_stat_bgwriter</structname> view will always have a
- single row with global data for the cluster.
+ single row, containing global data for the cluster.
</para>
<table id="pg-stat-database-view" xreflabel="pg_stat_database">
<tbody>
<row>
- <entry>datid</entry>
+ <entry><structfield>datid</></entry>
<entry><type>oid</></entry>
- <entry>The OID of the database</entry>
+ <entry>OID of a database</entry>
</row>
<row>
- <entry>datname</entry>
+ <entry><structfield>datname</></entry>
<entry><type>name</></entry>
- <entry>The name of the database</entry>
+ <entry>Name of this database</entry>
</row>
<row>
- <entry>numbackends</entry>
+ <entry><structfield>numbackends</></entry>
<entry><type>integer</></entry>
- <entry>The number of backends currently connected to this database.
- This is the only column in this view that returns a value for the
- current state, all other columns return the accumulated values since
+ <entry>Number of backends currently connected to this database.
+ This is the only column in this view that returns a value reflecting
+ current state; all other columns return the accumulated values since
the last reset. This value can also be returned by directly calling
the <function>pg_stat_get_db_numbackends</function> function.</entry>
</row>
<row>
- <entry>xact_commit</entry>
+ <entry><structfield>xact_commit</></entry>
<entry><type>bigint</></entry>
- <entry>The number of transactions in this database that have been
+ <entry>Number of transactions in this database that have been
committed. This value can also be returned by directly calling
the <function>pg_stat_get_db_xact_commit</function> function.</entry>
</row>
<row>
- <entry>xact_rollback</entry>
+ <entry><structfield>xact_rollback</></entry>
<entry><type>bigint</></entry>
- <entry>The number of transactions in this database that have been
+ <entry>Number of transactions in this database that have been
rolled back. This value can also be returned by directly calling
the <function>pg_stat_get_db_xact_rollback</function> function.</entry>
</row>
<row>
- <entry>blks_read</entry>
+ <entry><structfield>blks_read</></entry>
<entry><type>bigint</></entry>
- <entry>The number of disk blocks read in this database.
+ <entry>Number of disk blocks read in this database.
This value can also be returned by directly calling
the <function>pg_stat_get_db_blocks_fetched</function> and
<function>pg_stat_get_db_blocks_hit</function> functions and
subtracting the results.</entry>
</row>
<row>
- <entry>blks_hits</entry>
+ <entry><structfield>blks_hit</></entry>
<entry><type>bigint</></entry>
- <entry>The number of disk blocks read from the buffer cache
- (this only includes hits in the PostgreSQL buffer cache, and not
- the operating system filesystem cache).
+ <entry>Number of times disk blocks were found already in the buffer
+ cache, so that a read was not necessary (this only includes hits in the
+ PostgreSQL buffer cache, not the operating system's filesystem cache).
This value can also be returned by directly calling
the <function>pg_stat_get_db_blocks_hit</function> function.</entry>
</row>
<row>
- <entry>tup_returned</entry>
+ <entry><structfield>tup_returned</></entry>
<entry><type>bigint</></entry>
- <entry>The number of rows returned by queries in this database.
+ <entry>Number of rows returned by queries in this database.
This value can also be returned by directly calling
the <function>pg_stat_get_db_tuples_returned</function> function.</entry>
</row>
<row>
- <entry>tup_fetched</entry>
+ <entry><structfield>tup_fetched</></entry>
<entry><type>bigint</></entry>
- <entry>The number of rows fetched by queries in this database.
+ <entry>Number of rows fetched by queries in this database.
This value can also be returned by directly calling
the <function>pg_stat_get_db_tuples_fetched</function> function.</entry>
</row>
<row>
- <entry>tup_inserted</entry>
+ <entry><structfield>tup_inserted</></entry>
<entry><type>bigint</></entry>
- <entry>The number of rows inserted by queries in this database.
+ <entry>Number of rows inserted by queries in this database.
This value can also be returned by directly calling
the <function>pg_stat_get_db_tuples_inserted</function> function.</entry>
</row>
<row>
- <entry>tup_updated</entry>
+ <entry><structfield>tup_updated</></entry>
<entry><type>bigint</></entry>
- <entry>The number of rows updated by queries in this database.
+ <entry>Number of rows updated by queries in this database.
This value can also be returned by directly calling
the <function>pg_stat_get_db_tuples_updated</function> function.</entry>
</row>
<row>
- <entry>tup_deleted</entry>
+ <entry><structfield>tup_deleted</></entry>
<entry><type>bigint</></entry>
- <entry>The number of rows deleted by queries in this database.
+ <entry>Number of rows deleted by queries in this database.
This value can also be returned by directly calling
the <function>pg_stat_get_db_tuples_deleted</function> function.</entry>
</row>
<row>
- <entry>conflicts</entry>
+ <entry><structfield>conflicts</></entry>
<entry><type>bigint</></entry>
- <entry>
- The number of queries canceled due to conflict with recovery
- (on standby servers) in this database. (See
- <xref linkend="pg-stat-database-conflicts-view"> for more details).
+ <entry>Number of queries canceled due to conflicts with recovery
+ in this database. (Conflicts occur only on standby servers; see
+ <xref linkend="pg-stat-database-conflicts-view"> for details.)
This value can also be returned by directly calling
the <function>pg_stat_get_db_conflict_all</function> function.
</entry>
</row>
<row>
- <entry>temp_files</entry>
+ <entry><structfield>temp_files</></entry>
<entry><type>bigint</></entry>
- <entry>
- The number of temporary files written by queries in the database.
+ <entry>Number of temporary files created by queries in this database.
All temporary files are counted, regardless of why the temporary file
- was created (sorting or hash) or file size, and regardless of the
+ was created (e.g., sorting or hash), and regardless of the
<xref linkend="guc-log-temp-files"> setting.
This value can also be returned by directly calling
the <function>pg_stat_get_db_temp_files</function> function.
</entry>
</row>
<row>
- <entry>temp_bytes</entry>
+ <entry><structfield>temp_bytes</></entry>
<entry><type>bigint</></entry>
- <entry>
- The amount of data written to temporary files by queries in
- the database. All temporary files are counted, regardless of why
- the temporary file was created (sorting or hash) or file size, and
+ <entry>Total amount of data written to temporary files by queries in
+ this database. All temporary files are counted, regardless of why
+ the temporary file was created, and
regardless of the <xref linkend="guc-log-temp-files"> setting.
This value can also be returned by directly calling
the <function>pg_stat_get_db_temp_bytes</function> function.
</entry>
</row>
<row>
- <entry>deadlocks</entry>
+ <entry><structfield>deadlocks</></entry>
<entry><type>bigint</></entry>
- <entry>Number of deadlocks detected in the database.
+ <entry>Number of deadlocks detected in this database.
This value can also be returned by directly calling
the <function>pg_stat_get_db_deadlocks</function> function.</entry>
</row>
<row>
- <entry>block_read_time</entry>
+ <entry><structfield>block_read_time</></entry>
<entry><type>bigint</></entry>
- <entry>Time spent by backends reading data file blocks, in milliseconds.
+ <entry>Time spent reading data file blocks by backends in this database,
+ in milliseconds.
The same value can be returned in microseconds by directly calling
the <function>pg_stat_get_db_block_time_read</function> function.</entry>
</row>
<row>
- <entry>block_write_time</entry>
+ <entry><structfield>block_write_time</></entry>
<entry><type>bigint</></entry>
- <entry>Time spent by backends writing data file blocks, in milliseconds.
+ <entry>Time spent writing data file blocks by backends in this database,
+ in milliseconds.
The same value can be returned in microseconds by directly calling
the <function>pg_stat_get_db_block_time_write</function> function.</entry>
</row>
<row>
- <entry>stats_reset</entry>
- <entry><type>timestamptz</></entry>
- <entry>The last time the statistics were reset.
+ <entry><structfield>stats_reset</></entry>
+ <entry><type>timestamp with time zone</></entry>
+ <entry>Time at which these statistics were last reset.
This value can also be returned by directly calling
the <function>pg_stat_get_reset_time</function> function.</entry>
</row>
<para>
The <structname>pg_stat_database</structname> view will contain one row
- for each database in the cluster showing database-wide statistics.
- </para>
-
- <table id="pg-stat-database-conflicts-view" xreflabel="pg_stat_database_conflicts">
- <title>pg_stat_database_conflicts view</title>
- <tgroup cols="3">
- <thead>
- <row>
- <entry>Column</entry>
- <entry>Type</entry>
- <entry>Description</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry>datid</entry>
- <entry><type>oid</></entry>
- <entry>The OID of the database</entry>
- </row>
- <row>
- <entry>datname</entry>
- <entry><type>name</></entry>
- <entry>The name of the database</entry>
- </row>
- <row>
- <entry>confl_tablespace</entry>
- <entry><type>bigint</></entry>
- <entry>The number of queries that have been canceled due to
- dropped tablespaces. This value can also be returned by directly calling
- the <function>pg_stat_get_db_conflict_tablespace</function> function.</entry>
- </row>
- <row>
- <entry>confl_lock</entry>
- <entry><type>bigint</></entry>
- <entry>The number of queries that have been canceled due to
- lock timeouts. This value can also be returned by directly calling
- the <function>pg_stat_get_db_conflict_lock</function> function.</entry>
- </row>
- <row>
- <entry>confl_snapshot</entry>
- <entry><type>bigint</></entry>
- <entry>The number of queries that have been canceled due to
- old snapshots. This value can also be returned by directly calling
- the <function>pg_stat_get_db_conflict_snapshot</function> function.</entry>
- </row>
- <row>
- <entry>confl_bufferpin</entry>
- <entry><type>bigint</></entry>
- <entry>The number of queries that have been canceled due to
- pinned buffers. This value can also be returned by directly calling
- the <function>pg_stat_get_db_conflict_bufferpin</function> function.</entry>
- </row>
- <row>
- <entry>confl_deadlock</entry>
- <entry><type>bigint</></entry>
- <entry>The number of queries that have been canceled due to
- deadlocks. This value can also be returned by directly calling
- the <function>pg_stat_get_db_conflict_startup_deadlock</function>
- function.</entry>
- </row>
- </tbody>
- </tgroup>
- </table>
-
- <para>
- The <structname>pg_stat_database_conflicts</structname> view will contain
- one row per database showing database-wide statistics about
- query cancels due to conflict with recovery on standby servers.
- Will only contain information on standby servers, since
- conflicts do not occur on master servers.
- </para>
-
- <table id="pg-stat-replication-view" xreflabel="pg_stat_replication">
- <title>pg_stat_replication view</title>
- <tgroup cols="3">
- <thead>
- <row>
- <entry>Column</entry>
- <entry>Type</entry>
- <entry>Description</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry>pid</entry>
- <entry><type>integer</></entry>
- <entry>The process id of the WAL sender process</entry>
- </row>
- <row>
- <entry>usesysid</entry>
- <entry><type>oid</></entry>
- <entry>The OID of the user logged into this WAL sender process</entry>
- </row>
- <row>
- <entry>usename</entry>
- <entry><type>name</></entry>
- <entry>The name of the user logged into this WAL sender process</entry>
- </row>
- <row>
- <entry>application_name</entry>
- <entry><type>text</></entry>
- <entry>The name of the application that has initiated the connection
- to the WAL sender.</entry>
- </row>
- <row>
- <entry>client_addr</entry>
- <entry><type>inet</></entry>
- <entry>The remote IP of the client connected to the WAL sender.
- If this field is not set, it indicates that the client is
- connected via a Unix socket on the server machine.
- </entry>
- </row>
- <row>
- <entry>client_hostname</entry>
- <entry><type>text</></entry>
- <entry>
- If available, the hostname of the client as reported by a
- reverse lookup of <structfield>client_addr</>. This field will
- only be set when <xref linkend="guc-log-hostname"> is enabled.
- </entry>
- </row>
- <row>
- <entry>client_port</entry>
- <entry><type>integer</></entry>
- <entry>
- The remote TCP port that the client is using for communication
- to the, or <symbol>NULL</> if a unix socket is used.
- </entry>
- </row>
- <row>
- <entry>backend_start</entry>
- <entry><type>timestamp with time zone</></entry>
- <entry>
- The time when this process was started, i.e. when the
- client connected to the WAL sender.
- </entry>
- </row>
- <row>
- <entry>state</entry>
- <entry><type>text</></entry>
- <entry>Current WAL sender state</entry>
- </row>
- <row>
- <entry>sent_location</entry>
- <entry><type>text</></entry>
- <entry>Last transaction log position sent on this connection</entry>
- </row>
- <row>
- <entry>write_location</entry>
- <entry><type>text</></entry>
- <entry>Last transaction log position written to disk by the slave</entry>
- </row>
- <row>
- <entry>flush_location</entry>
- <entry><type>text</></entry>
- <entry>Last transaction log position flushed to disk by the slave</entry>
- </row>
- <row>
- <entry>replay_location</entry>
- <entry><type>text</></entry>
- <entry>Last transaction log position replayed into the database on the slave</entry>
- </row>
- <row>
- <entry>sync_priority</entry>
- <entry><type>int</></entry>
- <entry>
- The priority in the order which this slave will be picked as
- the synchronous standby.
- </entry>
- </row>
- <row>
- <entry>sync_state</entry>
- <entry><type>text</></entry>
- <entry>
- The synchronous state of this slave.
- </entry>
- </row>
- </tbody>
- </tgroup>
- </table>
-
- <para>
- The <structname>pg_stat_replication</structname> view will contain one row
- per WAL sender process, showing statistics about the replication to this
- slave. Only directly connected standbys are listed; no information about
- downstream standby servers is recorded.
+ for each database in the cluster, showing database-wide statistics.
</para>
<table id="pg-stat-all-tables-view" xreflabel="pg_stat_all_tables">
<tbody>
<row>
- <entry>relid</entry>
+ <entry><structfield>relid</></entry>
<entry><type>oid</></entry>
- <entry>The OID of the table</entry>
+ <entry>OID of a table</entry>
</row>
<row>
- <entry>schemaname</entry>
+ <entry><structfield>schemaname</></entry>
<entry><type>name</></entry>
- <entry>The name of the schema that the table is in</entry>
+ <entry>Name of the schema that this table is in</entry>
</row>
<row>
- <entry>relname</entry>
+ <entry><structfield>relname</></entry>
<entry><type>name</></entry>
- <entry>The name of the table</entry>
+ <entry>Name of this table</entry>
</row>
<row>
- <entry>seq_scan</entry>
+ <entry><structfield>seq_scan</></entry>
<entry><type>bigint</></entry>
- <entry>The number of sequential scans initiated on this table.
+ <entry>Number of sequential scans initiated on this table.
This value can also be returned by directly calling
the <function>pg_stat_get_numscans</function> function.</entry>
</row>
<row>
- <entry>seq_tup_read</entry>
+ <entry><structfield>seq_tup_read</></entry>
<entry><type>bigint</></entry>
- <entry>The number of live rows fetch by sequential scans.
+ <entry>Number of live rows fetched by sequential scans.
This value can also be returned by directly calling
the <function>pg_stat_get_tuples_returned</function> function.</entry>
</row>
<row>
- <entry>idx_scan</entry>
+ <entry><structfield>idx_scan</></entry>
<entry><type>bigint</></entry>
- <entry>The number of index scans initiated on this table</entry>
+ <entry>Number of index scans initiated on this table</entry>
</row>
<row>
- <entry>idx_tup_fetch</entry>
+ <entry><structfield>idx_tup_fetch</></entry>
<entry><type>bigint</></entry>
- <entry>The number of live rows fetch by index scans.</entry>
+ <entry>Number of live rows fetched by index scans</entry>
</row>
<row>
- <entry>n_tup_ins</entry>
+ <entry><structfield>n_tup_ins</></entry>
<entry><type>bigint</></entry>
- <entry>The number of rows inserted.
+ <entry>Number of rows inserted.
This value can also be returned by directly calling
the <function>pg_stat_get_tuples_inserted</function> function.</entry>
</row>
<row>
- <entry>n_tup_upd</entry>
+ <entry><structfield>n_tup_upd</></entry>
<entry><type>bigint</></entry>
- <entry>The number of rows updated.
+ <entry>Number of rows updated.
This value can also be returned by directly calling
the <function>pg_stat_get_tuples_updated</function> function.</entry>
</row>
<row>
- <entry>n_tup_del</entry>
+ <entry><structfield>n_tup_del</></entry>
<entry><type>bigint</></entry>
- <entry>The number of rows deleted.
+ <entry>Number of rows deleted.
This value can also be returned by directly calling
the <function>pg_stat_get_tuples_deleted</function> function.</entry>
</row>
<row>
- <entry>n_tup_hot_upd</entry>
+ <entry><structfield>n_tup_hot_upd</></entry>
<entry><type>bigint</></entry>
- <entry>The number of rows HOT (i.e., no separate index update) updated.
+ <entry>Number of rows HOT updated (i.e., with no separate index
+ update required).
This value can also be returned by directly calling
the <function>pg_stat_get_tuples_hot_updated</function> function.</entry>
</row>
<row>
- <entry>n_live_tup</entry>
+ <entry><structfield>n_live_tup</></entry>
<entry><type>bigint</></entry>
- <entry>The number of live rows.
+ <entry>Estimated number of live rows.
This value can also be returned by directly calling
the <function>pg_stat_get_live_tuples</function> function.</entry>
</row>
<row>
- <entry>n_dead_tup</entry>
+ <entry><structfield>n_dead_tup</></entry>
<entry><type>bigint</></entry>
- <entry>The number of dead rows.
+ <entry>Estimated number of dead rows.
This value can also be returned by directly calling
the <function>pg_stat_get_dead_tuples</function> function.</entry>
</row>
<row>
- <entry>last_vacuum</entry>
+ <entry><structfield>last_vacuum</></entry>
<entry><type>timestamp with time zone</></entry>
- <entry>The last time the table was manually non-<option>FULL</> vacuumed.
+ <entry>Last time at which this table was manually vacuumed
+ (not counting <command>VACUUM FULL</>).
This value can also be returned by directly calling
the <function>pg_stat_get_last_vacuum_time</function> function.</entry>
</row>
<row>
- <entry>last_autovacuum</entry>
+ <entry><structfield>last_autovacuum</></entry>
<entry><type>timestamp with time zone</></entry>
- <entry>The last time the table was vacuumed by the autovacuum daemon.
+ <entry>Last time at which this table was vacuumed by the autovacuum
+ daemon.
This value can also be returned by directly calling
the <function>pg_stat_get_last_autovacuum_time</function> function.</entry>
</row>
<row>
- <entry>last_analyze</entry>
+ <entry><structfield>last_analyze</></entry>
<entry><type>timestamp with time zone</></entry>
- <entry>The last time the table was manually analyzed.
+ <entry>Last time at which this table was manually analyzed.
This value can also be returned by directly calling
the <function>pg_stat_get_last_analyze_time</function> function.</entry>
</row>
<row>
- <entry>last_autoanalyze</entry>
+ <entry><structfield>last_autoanalyze</></entry>
<entry><type>timestamp with time zone</></entry>
- <entry>The last time the table was analyzed by the autovacuum daemon.
+ <entry>Last time at which this table was analyzed by the autovacuum
+ daemon.
This value can also be returned by directly calling
the <function>pg_stat_get_last_autoanalyze_time</function> function.</entry>
</row>
<row>
- <entry>vacuum_count</entry>
+ <entry><structfield>vacuum_count</></entry>
<entry><type>bigint</></entry>
- <entry>The number of times this table has been manually non-<option>FULL</> vacuumed.
- This value can also be returned by directly calling
- the <function>pg_stat_get_vacuum_count</function> function.</entry>
+ <entry>Number of times this table has been manually vacuumed
+ (not counting <command>VACUUM FULL</>)</entry>
</row>
<row>
- <entry>autovacuum_count</entry>
+ <entry><structfield>autovacuum_count</></entry>
<entry><type>bigint</></entry>
- <entry>The number of times this table has been vacuumed by the autovacuum daemon.
+ <entry>Number of times this table has been vacuumed by the autovacuum
+ daemon.
This value can also be returned by directly calling
the <function>pg_stat_get_autovacuum_count</function> function.</entry>
</row>
<row>
- <entry>analyze_count</entry>
+ <entry><structfield>analyze_count</></entry>
<entry><type>bigint</></entry>
- <entry>The number of times this table has been manually analyzed.
+ <entry>Number of times this table has been manually analyzed.
This value can also be returned by directly calling
the <function>pg_stat_get_analyze_count</function> function.</entry>
</row>
<row>
- <entry>autoanalyze_count</entry>
+ <entry><structfield>autoanalyze_count</></entry>
<entry><type>bigint</></entry>
- <entry>The number of times this table has been analyzed by the autovacuum daemon.
+ <entry>Number of times this table has been analyzed by the autovacuum
+ daemon.
This value can also be returned by directly calling
the <function>pg_stat_get_autoanalyze_count</function> function.</entry>
</row>
<para>
The <structname>pg_stat_all_tables</structname> view will contain
one row for each table in the current database (including TOAST
- tables) with information about accesses to this specific table. The
+ tables), showing statistics about accesses to that specific table. The
<structname>pg_stat_user_tables</structname> and
- <structname>pg_stat_sys_tables</structname> contain the same information,
- but filtered to only have rows for user and system tables.
+ <structname>pg_stat_sys_tables</structname> views
+ contain the same information,
+ but filtered to only show user and system tables respectively.
</para>
<table id="pg-stat-all-indexes-view" xreflabel="pg_stat_all_indexes">
<tbody>
<row>
- <entry>relid</entry>
+ <entry><structfield>relid</></entry>
<entry><type>oid</></entry>
- <entry>The OID of the table for this index</entry>
+ <entry>OID of the table for this index</entry>
</row>
<row>
- <entry>indexrelid</entry>
+ <entry><structfield>indexrelid</></entry>
<entry><type>oid</></entry>
- <entry>The OID of the index</entry>
+ <entry>OID of this index</entry>
</row>
<row>
- <entry>schemaname</entry>
+ <entry><structfield>schemaname</></entry>
<entry><type>name</></entry>
- <entry>The name of the schema the index is in</entry>
+ <entry>Name of the schema this index is in</entry>
</row>
<row>
- <entry>relname</entry>
+ <entry><structfield>relname</></entry>
<entry><type>name</></entry>
- <entry>The name of the table for this index</entry>
+ <entry>Name of the table for this index</entry>
</row>
<row>
- <entry>indexrelname</entry>
+ <entry><structfield>indexrelname</></entry>
<entry><type>name</></entry>
- <entry>The name of the index</entry>
+ <entry>Name of this index</entry>
</row>
<row>
- <entry>idx_scan</entry>
+ <entry><structfield>idx_scan</></entry>
<entry><type>bigint</></entry>
<entry>Number of index scans initiated on this index.
This value can also be returned by directly calling
the <function>pg_stat_get_numscans</function> function.</entry>
</row>
<row>
- <entry>idx_tup_read</entry>
+ <entry><structfield>idx_tup_read</></entry>
<entry><type>bigint</></entry>
<entry>Number of index entries returned by scans on this index.
This value can also be returned by directly calling
the <function>pg_stat_get_tuples_returned</function> function.</entry>
</row>
<row>
- <entry>idx_tup_fetch</entry>
+ <entry><structfield>idx_tup_fetch</></entry>
<entry><type>bigint</></entry>
- <entry>Number of live table rows fetched by simple index scans using this index.
+ <entry>Number of live table rows fetched by simple index scans using this
+ index.
This value can also be returned by directly calling
the <function>pg_stat_get_tuples_fetched</function> function.</entry>
</row>
<para>
The <structname>pg_stat_all_indexes</structname> view will contain
- one row for each index in the current database
- with information about accesses to this specific index. The
+ one row for each index in the current database,
+ showing statistics about accesses to that specific index. The
<structname>pg_stat_user_indexes</structname> and
- <structname>pg_stat_sys_indexes</structname> contain the same information,
- but filtered to only have rows for user and system indexes.
+ <structname>pg_stat_sys_indexes</structname> views
+ contain the same information,
+ but filtered to only show user and system indexes respectively.
</para>
+ <para>
+ Indexes can be used via either simple index scans or <quote>bitmap</>
+ index scans. In a bitmap scan
+ the output of several indexes can be combined via AND or OR rules,
+ so it is difficult to associate individual heap row fetches
+ with specific indexes when a bitmap scan is used. Therefore, a bitmap
+ scan increments the
+ <structname>pg_stat_all_indexes</>.<structfield>idx_tup_read</>
+ count(s) for the index(es) it uses, and it increments the
+ <structname>pg_stat_all_tables</>.<structfield>idx_tup_fetch</>
+ count for the table, but it does not affect
+ <structname>pg_stat_all_indexes</>.<structfield>idx_tup_fetch</>.
+ </para>
+
+ <note>
+ <para>
+ The <structfield>idx_tup_read</> and <structfield>idx_tup_fetch</> counts
+ can be different even without any use of bitmap scans,
+ because <structfield>idx_tup_read</> counts
+ index entries retrieved from the index while <structfield>idx_tup_fetch</>
+ counts live rows fetched from the table. The latter will be less if any
+ dead or not-yet-committed rows are fetched using the index, or if any
+ heap fetches are avoided by means of an index-only scan.
+ </para>
+ </note>
+
<table id="pg-statio-all-tables-view" xreflabel="pg_statio_all_tables">
<title>pg_statio_all_tables view</title>
<tgroup cols="3">
<tbody>
<row>
- <entry>relid</entry>
+ <entry><structfield>relid</></entry>
<entry><type>oid</></entry>
- <entry>The OID of the table</entry>
+ <entry>OID of a table</entry>
</row>
<row>
- <entry>schemaname</entry>
+ <entry><structfield>schemaname</></entry>
<entry><type>name</></entry>
- <entry>The name of the schema that the table is in</entry>
+ <entry>Name of the schema that this table is in</entry>
</row>
<row>
- <entry>relname</entry>
+ <entry><structfield>relname</></entry>
<entry><type>name</></entry>
- <entry>The name of the table</entry>
+ <entry>Name of this table</entry>
</row>
<row>
- <entry>heap_blks_read</entry>
- <entry><type>name</></entry>
+ <entry><structfield>heap_blks_read</></entry>
+ <entry><type>bigint</></entry>
<entry>Number of disk blocks read from this table.
This value can also be returned by directly calling
the <function>pg_stat_get_blocks_fetched</function> and
subtracting the results.</entry>
</row>
<row>
- <entry>heap_blks_hit</entry>
- <entry><type>name</></entry>
+ <entry><structfield>heap_blks_hit</></entry>
+ <entry><type>bigint</></entry>
<entry>Number of buffer hits in this table.
This value can also be returned by directly calling
the <function>pg_stat_get_blocks_hit</function> function.</entry>
</row>
<row>
- <entry>idx_blks_read</entry>
- <entry><type>name</></entry>
+ <entry><structfield>idx_blks_read</></entry>
+ <entry><type>bigint</></entry>
<entry>Number of disk blocks read from all indexes on this table</entry>
</row>
<row>
- <entry>idx_blks_hit</entry>
- <entry><type>name</></entry>
- <entry>Number of buffer hits in all indexes of this table.</entry>
+ <entry><structfield>idx_blks_hit</></entry>
+ <entry><type>bigint</></entry>
+ <entry>Number of buffer hits in all indexes of this table</entry>
</row>
<row>
- <entry>toast_blks_read</entry>
- <entry><type>name</></entry>
+ <entry><structfield>toast_blks_read</></entry>
+ <entry><type>bigint</></entry>
<entry>Number of disk blocks read from this table's TOAST table (if any)</entry>
</row>
<row>
- <entry>toast_blks_hit</entry>
- <entry><type>name</></entry>
+ <entry><structfield>toast_blks_hit</></entry>
+ <entry><type>bigint</></entry>
<entry>Number of buffer hits in this table's TOAST table (if any)</entry>
</row>
<row>
- <entry>tidx_blks_read</entry>
- <entry><type>name</></entry>
+ <entry><structfield>tidx_blks_read</></entry>
+ <entry><type>bigint</></entry>
<entry>Number of disk blocks read from this table's TOAST table index (if any)</entry>
</row>
<row>
- <entry>tidx_blks_hit</entry>
- <entry><type>name</></entry>
+ <entry><structfield>tidx_blks_hit</></entry>
+ <entry><type>bigint</></entry>
<entry>Number of buffer hits in this table's TOAST table index (if any)</entry>
</row>
</tbody>
<para>
The <structname>pg_statio_all_tables</structname> view will contain
one row for each table in the current database (including TOAST
- tables) with information about I/O on this specific table. The
+ tables), showing statistics about I/O on that specific table. The
<structname>pg_statio_user_tables</structname> and
- <structname>pg_statio_sys_tables</structname> contain the same information,
- but filtered to only have rows for user and system tables.
+ <structname>pg_statio_sys_tables</structname> views
+ contain the same information,
+ but filtered to only show user and system tables respectively.
</para>
<table id="pg-statio-all-indexes-view" xreflabel="pg_statio_all_indexes">
<tbody>
<row>
- <entry>relid</entry>
+ <entry><structfield>relid</></entry>
<entry><type>oid</></entry>
- <entry>The OID of the table for this index</entry>
+ <entry>OID of the table for this index</entry>
</row>
<row>
- <entry>indexrelid</entry>
+ <entry><structfield>indexrelid</></entry>
<entry><type>oid</></entry>
- <entry>The OID of the index</entry>
+ <entry>OID of this index</entry>
</row>
<row>
- <entry>schemaname</entry>
+ <entry><structfield>schemaname</></entry>
<entry><type>name</></entry>
- <entry>The name of the schema the index is in</entry>
+ <entry>Name of the schema this index is in</entry>
</row>
<row>
- <entry>relname</entry>
+ <entry><structfield>relname</></entry>
<entry><type>name</></entry>
- <entry>The name of the table for this index</entry>
+ <entry>Name of the table for this index</entry>
</row>
<row>
- <entry>indexrelname</entry>
+ <entry><structfield>indexrelname</></entry>
<entry><type>name</></entry>
- <entry>The name of the index</entry>
+ <entry>Name of this index</entry>
</row>
<row>
- <entry>idx_blks_read</entry>
- <entry><type>name</></entry>
- <entry>Number of disk blocks read from the index.
+ <entry><structfield>idx_blks_read</></entry>
+ <entry><type>bigint</></entry>
+ <entry>Number of disk blocks read from this index.
This value can also be returned by directly calling
the <function>pg_stat_get_blocks_fetched</function> and
<function>pg_stat_get_blocks_hit</function> functions and
subtracting the results.</entry>
</row>
<row>
- <entry>idx_blks_hit</entry>
- <entry><type>name</></entry>
- <entry>Number of buffer hits in the index.
+ <entry><structfield>idx_blks_hit</></entry>
+ <entry><type>bigint</></entry>
+ <entry>Number of buffer hits in this index.
This value can also be returned by directly calling
the <function>pg_stat_get_blocks_hit</function> function.</entry>
</row>
<para>
The <structname>pg_statio_all_indexes</structname> view will contain
- one row for each index in the current database
- with information about I/O on this specific index. The
+ one row for each index in the current database,
+ showing statistics about I/O on that specific index. The
<structname>pg_statio_user_indexes</structname> and
- <structname>pg_statio_sys_indexes</structname> contain the same information,
- but filtered to only have rows for user and system indexes.
+ <structname>pg_statio_sys_indexes</structname> views
+ contain the same information,
+ but filtered to only show user and system indexes respectively.
</para>
<table id="pg-statio-all-sequences-view" xreflabel="pg_statio_all_sequences">
<tbody>
<row>
- <entry>relid</entry>
+ <entry><structfield>relid</></entry>
<entry><type>oid</></entry>
- <entry>The OID of the sequence</entry>
+ <entry>OID of a sequence</entry>
</row>
<row>
- <entry>schemaname</entry>
+ <entry><structfield>schemaname</></entry>
<entry><type>name</></entry>
- <entry>The name of the schema the sequence is in</entry>
+ <entry>Name of the schema this sequence is in</entry>
</row>
<row>
- <entry>relname</entry>
+ <entry><structfield>relname</></entry>
<entry><type>name</></entry>
- <entry>The name of the sequence</entry>
+ <entry>Name of this sequence</entry>
</row>
<row>
- <entry>blks_read</entry>
- <entry><type>name</></entry>
- <entry>Number of disk blocks read from the sequence</entry>
+ <entry><structfield>blks_read</></entry>
+ <entry><type>bigint</></entry>
+ <entry>Number of disk blocks read from this sequence</entry>
</row>
<row>
- <entry>blks_hit</entry>
- <entry><type>name</></entry>
- <entry>Number of buffer hits in the sequence</entry>
+ <entry><structfield>blks_hit</></entry>
+ <entry><type>bigint</></entry>
+ <entry>Number of buffer hits in this sequence</entry>
</row>
</tbody>
</tgroup>
</table>
<para>
- The <structname>pg_statio_all_indexes</structname> view will contain
- one row for each sequence in the current database
- with information about I/O on this specific sequence.
+ The <structname>pg_statio_all_sequences</structname> view will contain
+ one row for each sequence in the current database,
+ showing statistics about I/O on that specific sequence.
</para>
<table id="pg-stat-user-functions-view" xreflabel="pg_stat_user_functions">
<tbody>
<row>
- <entry>funcid</entry>
+ <entry><structfield>funcid</></entry>
<entry><type>oid</></entry>
- <entry>The OID of the function</entry>
+ <entry>OID of a function</entry>
</row>
<row>
- <entry>schemaname</entry>
+ <entry><structfield>schemaname</></entry>
<entry><type>name</></entry>
- <entry>The name of the schema the function is in</entry>
+ <entry>Name of the schema this function is in</entry>
</row>
<row>
- <entry>funcname</entry>
+ <entry><structfield>funcname</></entry>
<entry><type>name</></entry>
- <entry>The name of the function</entry>
+ <entry>Name of this function</entry>
</row>
<row>
- <entry>calls</entry>
+ <entry><structfield>calls</></entry>
<entry><type>bigint</></entry>
- <entry>Number of times the function has been called.
+ <entry>Number of times this function has been called.
This value can also be returned by directly calling
the <function>pg_stat_get_function_calls</function> function.</entry>
</row>
<row>
- <entry>total_time</entry>
+ <entry><structfield>total_time</></entry>
<entry><type>bigint</></entry>
- <entry>Total time spent in this functions and all other functions
+ <entry>Total time spent in this function and all other functions
called by it, in milliseconds.
The same value can be returned in microseconds by directly calling
the <function>pg_stat_get_function_time</function> function.</entry>
</row>
<row>
- <entry>self_time</entry>
+ <entry><structfield>self_time</></entry>
<entry><type>bigint</></entry>
- <entry>Total time spent in this functions itself but not including
+ <entry>Total time spent in this function itself, not including
other functions called by it, in milliseconds.
The same value can be returned in microseconds by directly calling
the <function>pg_stat_get_function_self_time</function> function.</entry>
<para>
The <structname>pg_stat_user_functions</structname> view will contain
- one row for each tracked function (as specified by the
- <xref linkend="guc-track-functions"> parameter).
+ one row for each tracked function, showing statistics about executions of
+ that function. The <xref linkend="guc-track-functions"> parameter
+ controls exactly which functions are tracked.
+ </para>
+
+ <table id="pg-stat-replication-view" xreflabel="pg_stat_replication">
+ <title>pg_stat_replication view</title>
+ <tgroup cols="3">
+ <thead>
+ <row>
+ <entry>Column</entry>
+ <entry>Type</entry>
+ <entry>Description</entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry><structfield>pid</></entry>
+ <entry><type>integer</></entry>
+ <entry>Process ID of a WAL sender process</entry>
+ </row>
+ <row>
+ <entry><structfield>usesysid</></entry>
+ <entry><type>oid</></entry>
+ <entry>OID of the user logged into this WAL sender process</entry>
+ </row>
+ <row>
+ <entry><structfield>usename</></entry>
+ <entry><type>name</></entry>
+ <entry>Name of the user logged into this WAL sender process</entry>
+ </row>
+ <row>
+ <entry><structfield>application_name</></entry>
+ <entry><type>text</></entry>
+ <entry>Name of the application that is connected
+ to this WAL sender</entry>
+ </row>
+ <row>
+ <entry><structfield>client_addr</></entry>
+ <entry><type>inet</></entry>
+ <entry>IP address of the client connected to this WAL sender.
+ If this field is not set, it indicates that the client is
+ connected via a Unix socket on the server machine.
+ </entry>
+ </row>
+ <row>
+ <entry><structfield>client_hostname</></entry>
+ <entry><type>text</></entry>
+ <entry>Host name of the connected client, as reported by a
+ reverse DNS lookup of <structfield>client_addr</>. This field will
+ only be set for IP connections, and only when <xref
+ linkend="guc-log-hostname"> is enabled.
+ </entry>
+ </row>
+ <row>
+ <entry><structfield>client_port</></entry>
+ <entry><type>integer</></entry>
+ <entry>TCP port number that the client is using for communication
+ with this WAL sender, or <symbol>NULL</> if a Unix socket is used
+ </entry>
+ </row>
+ <row>
+ <entry><structfield>backend_start</></entry>
+ <entry><type>timestamp with time zone</></entry>
+ <entry>Time when this process was started, i.e., when the
+ client connected to this WAL sender
+ </entry>
+ </row>
+ <row>
+ <entry><structfield>state</></entry>
+ <entry><type>text</></entry>
+ <entry>Current WAL sender state</entry>
+ </row>
+ <row>
+ <entry><structfield>sent_location</></entry>
+ <entry><type>text</></entry>
+ <entry>Last transaction log position sent on this connection</entry>
+ </row>
+ <row>
+ <entry><structfield>write_location</></entry>
+ <entry><type>text</></entry>
+ <entry>Last transaction log position written to disk by this standby
+ server</entry>
+ </row>
+ <row>
+ <entry><structfield>flush_location</></entry>
+ <entry><type>text</></entry>
+ <entry>Last transaction log position flushed to disk by this standby
+ server</entry>
+ </row>
+ <row>
+ <entry><structfield>replay_location</></entry>
+ <entry><type>text</></entry>
+ <entry>Last transaction log position replayed into the database on this
+ standby server</entry>
+ </row>
+ <row>
+ <entry><structfield>sync_priority</></entry>
+ <entry><type>integer</></entry>
+ <entry>Priority of this standby server for being chosen as the
+ synchronous standby</entry>
+ </row>
+ <row>
+ <entry><structfield>sync_state</></entry>
+ <entry><type>text</></entry>
+ <entry>Synchronous state of this standby server</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <para>
+ The <structname>pg_stat_replication</structname> view will contain one row
+ per WAL sender process, showing statistics about replication to that
+ sender's connected standby server. Only directly connected standbys are
+ listed; no information is available about downstream standby servers.
+ </para>
+
+ <table id="pg-stat-database-conflicts-view" xreflabel="pg_stat_database_conflicts">
+ <title>pg_stat_database_conflicts view</title>
+ <tgroup cols="3">
+ <thead>
+ <row>
+ <entry>Column</entry>
+ <entry>Type</entry>
+ <entry>Description</entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry><structfield>datid</></entry>
+ <entry><type>oid</></entry>
+ <entry>OID of a database</entry>
+ </row>
+ <row>
+ <entry><structfield>datname</></entry>
+ <entry><type>name</></entry>
+ <entry>Name of this database</entry>
+ </row>
+ <row>
+ <entry><structfield>confl_tablespace</></entry>
+ <entry><type>bigint</></entry>
+ <entry>Number of queries in this database that have been canceled due to
+ dropped tablespaces. This value can also be returned by directly calling
+ the <function>pg_stat_get_db_conflict_tablespace</function> function.</entry>
+ </row>
+ <row>
+ <entry><structfield>confl_lock</></entry>
+ <entry><type>bigint</></entry>
+ <entry>Number of queries in this database that have been canceled due to
+ lock timeouts. This value can also be returned by directly calling
+ the <function>pg_stat_get_db_conflict_lock</function> function.</entry>
+ </row>
+ <row>
+ <entry><structfield>confl_snapshot</></entry>
+ <entry><type>bigint</></entry>
+ <entry>Number of queries in this database that have been canceled due to
+ old snapshots. This value can also be returned by directly calling
+ the <function>pg_stat_get_db_conflict_snapshot</function> function.</entry>
+ </row>
+ <row>
+ <entry><structfield>confl_bufferpin</></entry>
+ <entry><type>bigint</></entry>
+ <entry>Number of queries in this database that have been canceled due to
+ pinned buffers. This value can also be returned by directly calling
+ the <function>pg_stat_get_db_conflict_bufferpin</function> function.</entry>
+ </row>
+ <row>
+ <entry><structfield>confl_deadlock</></entry>
+ <entry><type>bigint</></entry>
+ <entry>Number of queries in this database that have been canceled due to
+ deadlocks. This value can also be returned by directly calling
+ the <function>pg_stat_get_db_conflict_startup_deadlock</function>
+ function.</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <para>
+ The <structname>pg_stat_database_conflicts</structname> view will contain
+ one row per database, showing database-wide statistics about
+ query cancels occurring due to conflicts with recovery on standby servers.
+ This view will only contain information on standby servers, since
+ conflicts do not occur on master servers.
</para>
- <sect3 id="monitoring-stats-functions">
- <title>Other Statistics Functions</title>
+ </sect2>
+ <sect2 id="monitoring-stats-functions">
+ <title>Statistics Functions</title>
+
+ <para>
+ Other ways of looking at the statistics can be set up by writing
+ queries that use the same underlying statistics access functions as
+ the standard views do. The per-database access
+ functions take a database OID as an argument to identify which
+ database to report on. The per-table and per-index functions take
+ a table or index OID. The functions for function-call statistics
+ take a function OID. (Note that only tables, indexes, and functions
+ in the current database can be seen with these functions.) The
+ per-server-process access functions take a server process
+ number, which ranges from one to the number of currently active
+ server processes.
+ </para>
+
+ <para>
+ Additional functions related to statistics collection are listed in <xref
+ linkend="monitoring-stats-funcs-table">.
+ </para>
<table id="monitoring-stats-funcs-table">
<title>Other Statistics Functions</title>
<entry><literal><function>pg_backend_pid()</function></literal></entry>
<entry><type>integer</type></entry>
<entry>
- Process ID of the server process attached to the current session
+ Process ID of the server process handling the current session
</entry>
</row>
</entry>
</row>
-
<row>
<entry><literal><function>pg_stat_get_wal_senders()</function></literal></entry>
<entry><type>setof record</type></entry>
<entry>
- One record for each active wal sender. The fields returned are a subset
+ One record for each active WAL sender. The fields returned are a subset
of those in the <structname>pg_stat_replication</structname> view.
</entry>
</row>
<entry><literal><function>pg_stat_reset_shared</function>(text)</literal></entry>
<entry><type>void</type></entry>
<entry>
- Reset some of the shared statistics counters for the database cluster to
- zero (requires superuser privileges). Calling
- <literal>pg_stat_reset_shared('bgwriter')</> will zero all the values shown by
- <structname>pg_stat_bgwriter</>.
+ Reset some cluster-wide statistics counters to zero, depending on the
+ argument (requires superuser privileges).
+ Calling <literal>pg_stat_reset_shared('bgwriter')</> will zero all the
+ counters shown in the <structname>pg_stat_bgwriter</> view.
</entry>
</row>
</tgroup>
</table>
- </sect3>
+ <para>
+ All the underlying functions of the <structname>pg_stat_activity</> view
+ require a backend ID number.
+ The function <function>pg_stat_get_backend_idset</function> provides a
+ convenient way to generate one row for each active server process for
+ invoking these functions. For example, to show the <acronym>PID</>s and
+ current queries of all server processes:
+
+<programlisting>
+SELECT pg_stat_get_backend_pid(s.backendid) AS pid,
+ pg_stat_get_backend_activity(s.backendid) AS query
+ FROM (SELECT pg_stat_get_backend_idset() AS backendid) AS s;
+</programlisting>
+ </para>
+
</sect2>
</sect1>
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