From 77bd49adba4711b4497e7e39a5ec3a9812cbd52a Mon Sep 17 00:00:00 2001
From: Magnus Hagander <magnus@hagander.net>
Date: Fri, 12 Apr 2019 14:04:50 +0200
Subject: Show shared object statistics in pg_stat_database

This adds a row to the pg_stat_database view with datoid 0 and datname
NULL for those objects that are not in a database. This was added
particularly for checksums, but we were already tracking more satistics
for these objects, just not returning it.

Also add a checksum_last_failure column that holds the timestamptz of
the last checksum failure that occurred in a database (or in a
non-dataabase file), if any.

Author: Julien Rouhaud <rjuju123@gmail.com>
---
 doc/src/sgml/monitoring.sgml        | 26 ++++++++++++++++++--------
 doc/src/sgml/ref/initdb.sgml        |  4 +++-
 doc/src/sgml/ref/pg_basebackup.sgml |  3 ++-
 3 files changed, 23 insertions(+), 10 deletions(-)

(limited to 'doc/src')

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 9cc332b6ad1..547fe4cce93 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -2498,20 +2498,22 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
     <row>
      <entry><structfield>datid</structfield></entry>
      <entry><type>oid</type></entry>
-     <entry>OID of a database</entry>
+     <entry>OID of this database, or 0 for objects belonging to a shared
+     relation</entry>
     </row>
     <row>
      <entry><structfield>datname</structfield></entry>
      <entry><type>name</type></entry>
-     <entry>Name of this database</entry>
+     <entry>Name of this database, or <literal>NULL</literal> for the shared
+     objects.</entry>
     </row>
     <row>
      <entry><structfield>numbackends</structfield></entry>
      <entry><type>integer</type></entry>
-     <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.</entry>
+     <entry>Number of backends currently connected to this database, or
+     <literal>NULL</literal> for the shared objects.  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.</entry>
     </row>
     <row>
      <entry><structfield>xact_commit</structfield></entry>
@@ -2597,7 +2599,14 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
     <row>
      <entry><structfield>checksum_failures</structfield></entry>
      <entry><type>bigint</type></entry>
-     <entry>Number of data page checksum failures detected in this database</entry>
+     <entry>Number of data page checksum failures detected in this
+     database</entry>
+    </row>
+    <row>
+     <entry><structfield>checksum_last_failure</structfield></entry>
+     <entry><type>timestamp with time zone</type></entry>
+     <entry>Time at which the last data page checksum failure was detected in
+     this database, or on a shared object.</entry>
     </row>
     <row>
      <entry><structfield>blk_read_time</structfield></entry>
@@ -2622,7 +2631,8 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
 
   <para>
    The <structname>pg_stat_database</structname> view will contain one row
-   for each database in the cluster, showing database-wide statistics.
+   for each database in the cluster, plus one for the shared objects, showing
+   database-wide statistics.
   </para>
 
   <table id="pg-stat-database-conflicts-view" xreflabel="pg_stat_database_conflicts">
diff --git a/doc/src/sgml/ref/initdb.sgml b/doc/src/sgml/ref/initdb.sgml
index 7f323103084..7fc3152c6d3 100644
--- a/doc/src/sgml/ref/initdb.sgml
+++ b/doc/src/sgml/ref/initdb.sgml
@@ -218,7 +218,9 @@ PostgreSQL documentation
         I/O system that would otherwise be silent. Enabling checksums
         may incur a noticeable performance penalty. This option can only
         be set during initialization, and cannot be changed later. If
-        set, checksums are calculated for all objects, in all databases.
+        set, checksums are calculated for all objects, in all databases. All
+        checksum failures will be reported in the <xref
+        linkend="pg-stat-database-view"/> view.
        </para>
       </listitem>
      </varlistentry>
diff --git a/doc/src/sgml/ref/pg_basebackup.sgml b/doc/src/sgml/ref/pg_basebackup.sgml
index 830e87fc6ae..fc9e222f8d0 100644
--- a/doc/src/sgml/ref/pg_basebackup.sgml
+++ b/doc/src/sgml/ref/pg_basebackup.sgml
@@ -531,7 +531,8 @@ PostgreSQL documentation
         By default, checksums are verified and checksum failures will result
         in a non-zero exit status. However, the base backup will not be
         removed in such a case, as if the <option>--no-clean</option> option
-        had been used.
+        had been used.  Checksum verifications failures will also be reported
+        in the <xref linkend="pg-stat-database-view"/> view.
        </para>
       </listitem>
      </varlistentry>
-- 
cgit v1.2.3