<row>

<entry><structname>pg_stat_recovery_prefetch</structname><indexterm><primary>pg_stat_recovery_prefetch</primary></indexterm></entry>

<entry>Only one row, showing statistics about blocks prefetched during recovery.

See <xref linkend="pg-stat-recovery-prefetch-view"/> for details.

See <link linkend="monitoring-pg-stat-recovery-prefetch">

<structname>pg_stat_recovery_prefetch</structname></link> for details.

</entry>

</row>

</sect2>

<sect2 id="monitoring-pg-stat-subscription">

<title><structname>pg_stat_subscription</structname></title>

<sect2 id="monitoring-pg-stat-recovery-prefetch">

<title><structname>pg_stat_recovery_prefetch</structname></title>

<indexterm>

<primary>pg_stat_subscription</primary>

<primary>pg_stat_recovery_prefetch</primary>

</indexterm>

<para>

The <structname>pg_stat_subscription</structname> view will contain one

row per subscription for main worker (with null PID if the worker is

not running), and additional rows for workers handling the initial data

copy of the subscribed tables.

The <structname>pg_stat_recovery_prefetch</structname> view will contain

only one row. The columns <structfield>wal_distance</structfield>,

<structfield>block_distance</structfield> and

<structfield>io_depth</structfield> show current values, and the

other columns show cumulative counters that can be reset

with the <function>pg_stat_reset_shared</function> function.

</para>

<table id="pg-stat-recovery-prefetch-view" xreflabel="pg_stat_recovery_prefetch">

<title><structname>pg_stat_recovery_prefetch</structname> View</title>

<tgroup cols="3">

<tgroup cols="1">

<thead>

<row>

<entry>Column</entry>

<entry>Type</entry>

<entry>Description</entry>

<row>

<entry role="catalog_table_entry"><para role="column_definition">

Column Type

</para>

<para>

Description

</para></entry>

</row>

</thead>

<tbody>

<row>

<entry><structfield>prefetch</structfield></entry>

<entry><type>bigint</type></entry>

<entry>Number of blocks prefetched because they were not in the buffer pool</entry>

</row>

<row>

<entry><structfield>hit</structfield></entry>

<entry><type>bigint</type></entry>

<entry>Number of blocks not prefetched because they were already in the buffer pool</entry>

</row>

<row>

<entry><structfield>skip_init</structfield></entry>

<entry><type>bigint</type></entry>

<entry>Number of blocks not prefetched because they would be zero-initialized</entry>

</row>

<row>

<entry><structfield>skip_new</structfield></entry>

<entry><type>bigint</type></entry>

<entry>Number of blocks not prefetched because they didn't exist yet</entry>

</row>

<row>

<entry><structfield>skip_fpw</structfield></entry>

<entry><type>bigint</type></entry>

<entry>Number of blocks not prefetched because a full page image was included in the WAL</entry>

</row>

<row>

<entry><structfield>skip_rep</structfield></entry>

<entry><type>bigint</type></entry>

<entry>Number of blocks not prefetched because they were already recently prefetched</entry>

</row>

<row>

<entry><structfield>wal_distance</structfield></entry>

<entry><type>integer</type></entry>

<entry>How many bytes ahead the prefetcher is looking</entry>

</row>

<row>

<entry><structfield>block_distance</structfield></entry>

<entry><type>integer</type></entry>

<entry>How many blocks ahead the prefetcher is looking</entry>

</row>

<row>

<entry><structfield>io_depth</structfield></entry>

<entry><type>integer</type></entry>

<entry>How many prefetches have been initiated but are not yet known to have completed</entry>

</row>

<tbody>

<row>

<entry role="catalog_table_entry">

<para role="column_definition">

<structfield>prefetch</structfield> <type>bigint</type>

</para>

<para>

Number of blocks prefetched because they were not in the buffer pool

</para>

</entry>

</row>

<row>

<entry role="catalog_table_entry">

<para role="column_definition">

<structfield>hit</structfield> <type>bigint</type>

</para>

<para>

Number of blocks not prefetched because they were already in the buffer pool

</para>

</entry>

</row>

<row>

<entry role="catalog_table_entry">

<para role="column_definition">

<structfield>skip_init</structfield> <type>bigint</type>

</para>

<para>

Number of blocks not prefetched because they would be zero-initialized

</para>

</entry>

</row>

<row>

<entry role="catalog_table_entry">

<para role="column_definition">

<structfield>skip_new</structfield> <type>bigint</type>

</para>

<para>

Number of blocks not prefetched because they didn't exist yet

</para>

</entry>

</row>

<row>

<entry role="catalog_table_entry">

<para role="column_definition">

<structfield>skip_fpw</structfield> <type>bigint</type>

</para>

<para>

Number of blocks not prefetched because a full page image was included in the WAL

</para>

</entry>

</row>

<row>

<entry role="catalog_table_entry">

<para role="column_definition">

<structfield>skip_rep</structfield> <type>bigint</type>

</para>

<para>

Number of blocks not prefetched because they were already recently prefetched

</para>

</entry>

</row>

<row>

<entry role="catalog_table_entry">

<para role="column_definition">

<structfield>wal_distance</structfield> <type>int</type>

</para>

<para>

How many bytes ahead the prefetcher is looking

</para>

</entry>

</row>

<row>

<entry role="catalog_table_entry">

<para role="column_definition">

<structfield>block_distance</structfield> <type>int</type>

</para>

<para>

How many blocks ahead the prefetcher is looking

</para>

</entry>

</row>

<row>

<entry role="catalog_table_entry">

<para role="column_definition">

<structfield>io_depth</structfield> <type>int</type>

</para>

<para>

How many prefetches have been initiated but are not yet known to have completed

</para>

</entry>

</row>

</tbody>

</tgroup>

</table>

<para>

</para>

</sect2>

</indexterm>

<table id="pg-stat-subscription" xreflabel="pg_stat_subscription">

<title><structname>pg_stat_subscription</structname> View</title>