From ec2b614282f5f661708413b72a94586d95ea0366 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Thu, 20 Feb 2020 18:16:39 +0100
Subject: [PATCH v3 3/4] Add backend type to csvlog and optionally
 log_line_prefix

---
 doc/src/sgml/config.sgml                      |  8 ++++-
 src/backend/utils/error/elog.c                | 29 +++++++++++++++++++
 src/backend/utils/misc/postgresql.conf.sample |  1 +
 src/test/regress/pg_regress.c                 |  2 +-
 4 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index c1128f89ec..206778b1c3 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -6470,6 +6470,11 @@ <title>What to Log</title>
              <entry>Application name</entry>
              <entry>yes</entry>
             </row>
+            <row>
+             <entry><literal>%b</literal></entry>
+             <entry>Backend process type</entry>
+             <entry>yes</entry>
+            </row>
             <row>
              <entry><literal>%u</literal></entry>
              <entry>User name</entry>
@@ -6785,7 +6790,7 @@ <title>Using CSV-Format Log Output</title>
         character count of the error position therein,
         location of the error in the PostgreSQL source code
         (if <varname>log_error_verbosity</varname> is set to <literal>verbose</literal>),
-        and application name.
+        application name, and backend type.
         Here is a sample table definition for storing CSV-format log output:
 
 <programlisting>
@@ -6814,6 +6819,7 @@ <title>Using CSV-Format Log Output</title>
   query_pos integer,
   location text,
   application_name text,
+  backend_type text,
   PRIMARY KEY (session_id, session_line_num)
 );
 </programlisting>
diff --git a/src/backend/utils/error/elog.c b/src/backend/utils/error/elog.c
index f5b0211f66..bb65eb41ca 100644
--- a/src/backend/utils/error/elog.c
+++ b/src/backend/utils/error/elog.c
@@ -72,6 +72,8 @@
 #include "libpq/pqformat.h"
 #include "mb/pg_wchar.h"
 #include "miscadmin.h"
+#include "pgstat.h"
+#include "postmaster/bgworker.h"
 #include "postmaster/postmaster.h"
 #include "postmaster/syslogger.h"
 #include "storage/ipc.h"
@@ -2492,6 +2494,23 @@ log_line_prefix(StringInfo buf, ErrorData *edata)
 										   padding > 0 ? padding : -padding);
 
 				break;
+			case 'b':
+				{
+					const char *backend_type_str;
+
+					if (MyProcPid == PostmasterPid)
+						backend_type_str = "postmaster";
+					else if (MyBackendType == B_BG_WORKER)
+						backend_type_str = MyBgworkerEntry->bgw_type;
+					else
+						backend_type_str = pgstat_get_backend_desc(MyBackendType);
+
+					if (padding != 0)
+						appendStringInfo(buf, "%*s", padding, backend_type_str);
+					else
+						appendStringInfoString(buf, backend_type_str);
+					break;
+				}
 			case 'u':
 				if (MyProcPort)
 				{
@@ -2920,6 +2939,16 @@ write_csvlog(ErrorData *edata)
 	if (application_name)
 		appendCSVLiteral(&buf, application_name);
 
+	appendStringInfoChar(&buf, ',');
+
+	/* backend type */
+	if (MyProcPid == PostmasterPid)
+		appendCSVLiteral(&buf, "postmaster");
+	else if (MyBackendType == B_BG_WORKER)
+		appendCSVLiteral(&buf, MyBgworkerEntry->bgw_type);
+	else
+		appendCSVLiteral(&buf, pgstat_get_backend_desc(MyBackendType));
+
 	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 e58e4788a8..c0e9531f9c 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -524,6 +524,7 @@
 #log_hostname = off
 #log_line_prefix = '%m [%p] '		# special values:
 					#   %a = application name
+					#   %b = backend type
 					#   %u = user name
 					#   %d = database name
 					#   %r = remote host and port
diff --git a/src/test/regress/pg_regress.c b/src/test/regress/pg_regress.c
index a53e4a6243..f6a5e1b9c7 100644
--- a/src/test/regress/pg_regress.c
+++ b/src/test/regress/pg_regress.c
@@ -2334,7 +2334,7 @@ regression_main(int argc, char *argv[], init_function ifunc, test_function tfunc
 		fputs("\n# Configuration added by pg_regress\n\n", pg_conf);
 		fputs("log_autovacuum_min_duration = 0\n", pg_conf);
 		fputs("log_checkpoints = on\n", pg_conf);
-		fputs("log_line_prefix = '%m [%p] %q%a '\n", pg_conf);
+		fputs("log_line_prefix = '%m %b[%p] %q%a '\n", pg_conf);
 		fputs("log_lock_waits = on\n", pg_conf);
 		fputs("log_temp_files = 128kB\n", pg_conf);
 		fputs("max_prepared_transactions = 2\n", pg_conf);
-- 
2.25.0