1 files changed, 29 insertions, 0 deletions
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index b001ce548d8..c0b94bc0728 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -14997,6 +14997,12 @@ SELECT * FROM pg_ls_dir('.') WITH ORDINALITY AS t(ls,n);
       </row>
 
       <row>
+       <entry><literal><function>pg_blocking_pids(<type>int</type>)</function></literal></entry>
+       <entry><type>int[]</type></entry>
+       <entry>Process ID(s) that are blocking specified server process ID</entry>
+      </row>
+
+      <row>
        <entry><literal><function>pg_conf_load_time()</function></literal></entry>
        <entry><type>timestamp with time zone</type></entry>
        <entry>configuration load time</entry>
@@ -15184,6 +15190,29 @@ SET search_path TO <replaceable>schema</> <optional>, <replaceable>schema</>, ..
    </para>
 
    <indexterm>
+    <primary>pg_blocking_pids</primary>
+   </indexterm>
+
+   <para>
+    <function>pg_blocking_pids</function> returns an array of the process IDs
+    of the sessions that are blocking the server process with the specified
+    process ID, or an empty array if there is no such server process or it is
+    not blocked.  One server process blocks another if it either holds a lock
+    that conflicts with the blocked process's lock request (hard block), or is
+    waiting for a lock that would conflict with the blocked process's lock
+    request and is ahead of it in the wait queue (soft block).  When using
+    parallel queries the result always lists client-visible process IDs (that
+    is, <function>pg_backend_pid</> results) even if the actual lock is held
+    or awaited by a child worker process.  As a result of that, there may be
+    duplicated PIDs in the result.  Also note that when a prepared transaction
+    holds a conflicting lock, it will be represented by a zero process ID in
+    the result of this function.
+    Frequent calls to this function could have some impact on database
+    performance, because it needs exclusive access to the lock manager's
+    shared state for a short time.
+   </para>
+
+   <indexterm>
     <primary>pg_conf_load_time</primary>
    </indexterm>