diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 994155ca00..7a7177c550 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -6694,6 +6694,12 @@ local0.* /var/log/postgresql
Process ID
no
+
+ %P
+ Process ID of the parallel group leader, if this process
+ is a parallel query worker
+ no
+
%t
Time stamp without milliseconds
@@ -7026,7 +7032,7 @@ log_line_prefix = '%m [%p] %q%u@%d/%a '
character count of the error position therein,
location of the error in the PostgreSQL source code
(if log_error_verbosity is set to verbose),
- application name, and backend type.
+ application name, backend type, and process ID of parallel group leader.
Here is a sample table definition for storing CSV-format log output:
@@ -7056,6 +7062,7 @@ CREATE TABLE postgres_log
location text,
application_name text,
backend_type text,
+ leader_pid integer,
PRIMARY KEY (session_id, session_line_num)
);
diff --git a/src/backend/utils/error/elog.c b/src/backend/utils/error/elog.c
index e4b717c79a..d0b368530e 100644
--- a/src/backend/utils/error/elog.c
+++ b/src/backend/utils/error/elog.c
@@ -2448,6 +2448,29 @@ log_line_prefix(StringInfo buf, ErrorData *edata)
else
appendStringInfo(buf, "%d", MyProcPid);
break;
+
+ case 'P':
+ if (MyProc)
+ {
+ PGPROC *leader = MyProc->lockGroupLeader;
+
+ /*
+ * Show the leader only for active parallel workers. This
+ * leaves out the leader of a parallel group.
+ */
+ if (leader == NULL || leader->pid == MyProcPid)
+ appendStringInfoSpaces(buf,
+ padding > 0 ? padding : -padding);
+ else if (padding != 0)
+ appendStringInfo(buf, "%*d", padding, leader->pid);
+ else
+ appendStringInfo(buf, "%d", leader->pid);
+ }
+ else if (padding != 0)
+ appendStringInfoSpaces(buf,
+ padding > 0 ? padding : -padding);
+ break;
+
case 'l':
if (padding != 0)
appendStringInfo(buf, "%*ld", padding, log_line_number);
@@ -2836,6 +2859,21 @@ write_csvlog(ErrorData *edata)
else
appendCSVLiteral(&buf, GetBackendTypeDesc(MyBackendType));
+ appendStringInfoChar(&buf, ',');
+
+ /* leader PID */
+ if (MyProc)
+ {
+ PGPROC *leader = MyProc->lockGroupLeader;
+
+ /*
+ * Show the leader only for active parallel workers. This leaves out
+ * the leader of a parallel group.
+ */
+ if (leader && leader->pid != MyProcPid)
+ appendStringInfo(&buf, "%d", leader->pid);
+ }
+
appendStringInfoChar(&buf, '\n');
/* If in the syslogger process, try to write messages direct to file */
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index b0715ae188..9cb571f7cc 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -537,6 +537,7 @@
# %h = remote host
# %b = backend type
# %p = process ID
+ # %P = process ID of parallel group leader
# %t = timestamp without milliseconds
# %m = timestamp with milliseconds
# %n = timestamp with milliseconds (as a Unix epoch)