[Peter Eisentraut <peter.eisentraut@2ndquadrant.com>]

In PG13, we added the ability to add backtraces to the log output. 
After some practical experience with it, I think the order in which the 
BACKTRACE and the LOCATION fields are printed is wrong.  I propose we 
put the LOCATION field before the BACKTRACE field, not after.  This 
makes more sense because the location is effectively at the lowest level 
of the backtrace.

Patch attached.

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Attachments:

0001-Log-the-location-field-before-any-backtrace.patch (text/plain, 1.4K) download
From aaf4a8146cf60a5959e50432359fd9972f410e1b Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Thu, 9 Jul 2020 11:00:34 +0200
Subject: [PATCH] Log the location field before any backtrace

This order makes more sense because the location is effectively at the
lowest level of the backtrace.
---
 src/backend/utils/error/elog.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/backend/utils/error/elog.c b/src/backend/utils/error/elog.c
index e976201030..e4b717c79a 100644
--- a/src/backend/utils/error/elog.c
+++ b/src/backend/utils/error/elog.c
@@ -2938,13 +2938,6 @@ send_message_to_server_log(ErrorData *edata)
 			append_with_tabs(&buf, edata->context);
 			appendStringInfoChar(&buf, '\n');
 		}
-		if (edata->backtrace)
-		{
-			log_line_prefix(&buf, edata);
-			appendStringInfoString(&buf, _("BACKTRACE:  "));
-			append_with_tabs(&buf, edata->backtrace);
-			appendStringInfoChar(&buf, '\n');
-		}
 		if (Log_error_verbosity >= PGERROR_VERBOSE)
 		{
 			/* assume no newlines in funcname or filename... */
@@ -2962,6 +2955,13 @@ send_message_to_server_log(ErrorData *edata)
 								 edata->filename, edata->lineno);
 			}
 		}
+		if (edata->backtrace)
+		{
+			log_line_prefix(&buf, edata);
+			appendStringInfoString(&buf, _("BACKTRACE:  "));
+			append_with_tabs(&buf, edata->backtrace);
+			appendStringInfoChar(&buf, '\n');
+		}
 	}
 
 	/*
-- 
2.27.0