0002-parameter-max_log_size-to-truncate-logs.patch

From d2eb9ccde970f752be12ce4dbcf40c55806599c9 Mon Sep 17 00:00:00 2001
From: diphantxm <diphantxm@yandex-team.ru>
Date: Tue, 1 Oct 2024 17:28:16 +0300
Subject: [PATCH] parameter max_log_size to truncate logs

There is no need to log the entire query, because it may be large and take lots of space on disk. Parameter max_log_size set the maximum length for logged query. Everything beyond that length is truncated. Value 0 disables the parameter.
---
 src/backend/utils/error/elog.c                |  8 ++++++++
 src/backend/utils/misc/guc_tables.c           | 11 +++++++++++
 src/backend/utils/misc/postgresql.conf.sample |  2 ++
 src/bin/pg_ctl/t/004_logrotate.pl             | 15 +++++++++++++++
 src/include/utils/elog.h                      |  1 +
 5 files changed, 37 insertions(+)

diff --git a/src/backend/utils/error/elog.c b/src/backend/utils/error/elog.c
index 5cbb5b5416..0690ec57ce 100644
--- a/src/backend/utils/error/elog.c
+++ b/src/backend/utils/error/elog.c
@@ -111,6 +111,7 @@ int			Log_destination = LOG_DESTINATION_STDERR;
 char	   *Log_destination_string = NULL;
 bool		syslog_sequence_numbers = true;
 bool		syslog_split_messages = true;
+int			max_log_size = 0;
 
 /* Processed form of backtrace_functions GUC */
 static char *backtrace_function_list;
@@ -1693,6 +1694,13 @@ EmitErrorReport(void)
 	CHECK_STACK_DEPTH();
 	oldcontext = MemoryContextSwitchTo(edata->assoc_context);
 
+	if (max_log_size != 0 && debug_query_string != NULL)
+	{
+		char* str = debug_query_string;
+		str[pg_mbcliplen(str, strlen(str), max_log_size)] = '\0';
+		debug_query_string = str;
+	}
+
 	/*
 	 * Reset the formatted timestamp fields before emitting any logs.  This
 	 * includes all the log destinations and emit_log_hook, as the latter
diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c
index 686309db58..cf1404c059 100644
--- a/src/backend/utils/misc/guc_tables.c
+++ b/src/backend/utils/misc/guc_tables.c
@@ -3714,6 +3714,17 @@ struct config_int ConfigureNamesInt[] =
 		NULL, NULL, NULL
 	},
 
+	{
+		{"max_log_size", PGC_SIGHUP, LOGGING_WHAT,
+			gettext_noop("Sets max size of logged statement."),
+			NULL
+		},
+		&max_log_size,
+		5 * (1024 * 1024),
+		0, INT_MAX,
+		NULL, NULL, NULL
+	},
+
 	/* End-of-list marker */
 	{
 		{NULL, 0, 0, NULL, NULL}, NULL, 0, 0, 0, NULL, NULL, NULL
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 667e0dc40a..0ffb32d5fb 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -615,6 +615,8 @@
 					# bind-parameter values to N bytes;
 					# -1 means print in full, 0 disables
 #log_statement = 'none'			# none, ddl, mod, all
+#max_log_size = 0 				# max size of logged statement_timeout
+				    # 0 disables the feature
 #log_replication_commands = off
 #log_temp_files = -1			# log temporary files equal or larger
 					# than the specified size in kilobytes;
diff --git a/src/bin/pg_ctl/t/004_logrotate.pl b/src/bin/pg_ctl/t/004_logrotate.pl
index eacca1a652..1c1f89cb0a 100644
--- a/src/bin/pg_ctl/t/004_logrotate.pl
+++ b/src/bin/pg_ctl/t/004_logrotate.pl
@@ -69,6 +69,7 @@ log_destination = 'stderr, csvlog, jsonlog'
 # these ensure stability of test results:
 log_rotation_age = 0
 lc_messages = 'C'
+max_log_size = 32
 ));
 
 $node->start();
@@ -135,6 +136,20 @@ check_log_pattern('stderr', $new_current_logfiles, 'syntax error', $node);
 check_log_pattern('csvlog', $new_current_logfiles, 'syntax error', $node);
 check_log_pattern('jsonlog', $new_current_logfiles, 'syntax error', $node);
 
+$node->psql('postgres', 'INSERT INTO SOME_NON_EXISTANT_TABLE VALUES (TEST)');
+for (my $attempts = 0; $attempts < $max_attempts; $attempts++)
+{
+	eval {
+		$current_logfiles = slurp_file($node->data_dir . '/current_logfiles');
+	};
+	last unless $@;
+	usleep(100_000);
+}
+die $@ if $@;
+check_log_pattern('stderr',  $current_logfiles, 'INSERT INTO SOME_NON_EXISTANT_TA(?!(BLE VALUES \(TEST\)))', $node);
+check_log_pattern('csvlog',  $current_logfiles, 'INSERT INTO SOME_NON_EXISTANT_TA(?!(BLE VALUES \(TEST\)))', $node);
+check_log_pattern('jsonlog', $current_logfiles, 'INSERT INTO SOME_NON_EXISTANT_TA(?!(BLE VALUES \(TEST\)))', $node);
+
 $node->stop();
 
 done_testing();
diff --git a/src/include/utils/elog.h b/src/include/utils/elog.h
index e54eca5b48..a8e30006f2 100644
--- a/src/include/utils/elog.h
+++ b/src/include/utils/elog.h
@@ -502,6 +502,7 @@ extern PGDLLIMPORT int Log_destination;
 extern PGDLLIMPORT char *Log_destination_string;
 extern PGDLLIMPORT bool syslog_sequence_numbers;
 extern PGDLLIMPORT bool syslog_split_messages;
+extern PGDLLIMPORT int max_log_size;
 
 /* Log destination bitmap */
 #define LOG_DESTINATION_STDERR	 1
-- 
2.39.2 (Apple Git-143)