On Wed, Mar 11, 2026 at 6:05 AM vignesh C <[email protected]> wrote:

> On Tue, 10 Mar 2026 at 04:26, Gyan Sreejith <[email protected]>
> wrote:
> >
> > On Thu, Mar 5, 2026 at 9:49 AM Euler Taveira <[email protected]> wrote:
> >
> >> Don't duplicate code. If you are reusing a function, my advice is to
> move it to
> >> src/common. You can always use "ifdef FRONTEND" to use the appropriate
> log
> >> message (elog/ereport vs pg_error, for example).
> >
> >
> > I have made all the changes except for this one, and I am deferring to
> Amit Kapila regarding the marks.
>
> Few comments:
> 1) You are not checking log level because of which the contents are
> logged irrespective of the log level:
> +#undef pg_log_info
> +#define pg_log_info(...) do{\
> +       if (internal_log_file_fp != NULL) \
> +               internal_log_file_write(__VA_ARGS__); \
> +       else \
> +               pg_log_generic(PG_LOG_INFO,PG_LOG_PRIMARY,__VA_ARGS__);\
> +} while(0)
> +
> +#undef pg_log_info_hint
> +#define pg_log_info_hint(...) do{\
> +       if (internal_log_file_fp != NULL) \
> +               internal_log_file_write(__VA_ARGS__); \
> +       else \
> +               pg_log_generic(PG_LOG_INFO, PG_LOG_HINT, __VA_ARGS__);\
> +} while(0)
> +
> +#undef pg_log_debug
> +#define pg_log_debug(...) do{\
> +       if (internal_log_file_fp != NULL) \
> +               internal_log_file_write(__VA_ARGS__); \
> +       else \
> +               if (unlikely(__pg_log_level <= PG_LOG_DEBUG)) \
> +                       pg_log_generic(PG_LOG_DEBUG, PG_LOG_PRIMARY,
> __VA_ARGS__); \
> +} while(0)

The log level is passed to and checked by pg_log_generic_v() which is
called by pg_log_generic().

>
>
2) Instead of just checking if the file is created or not, let's check
> for some contents from the file:
>
Added checks to ensure that the log files are not empty, thanks!

>
> 3) This change is not required, let's remove this:
> --- a/src/bin/pg_basebackup/t/040_pg_createsubscriber.pl
> +++ b/src/bin/pg_basebackup/t/040_pg_createsubscriber.pl
> @@ -13,7 +13,8 @@ program_help_ok('pg_createsubscriber');
>  program_version_ok('pg_createsubscriber');
>  program_options_handling_ok('pg_createsubscriber');
>
> -my $datadir = PostgreSQL::Test::Utils::tempdir;
> +my $datadir = PostgreSQL::Test::Utils::tempdir + "/datadir";

Fixed

>
>
4) No need of '{' as it is a single line statement
> if (opt->log_dir != NULL)
> {
> appendPQExpBuffer(pg_ctl_cmd, " -l %s/%s/%s.log", opt->log_dir,
> log_timestamp, SERVER_LOG_FILE_NAME);
> }
>
Fixed

Thank you! I have attached the changes.
Regards,
Gyan
From 7a2073c4be92e73619e3f19ea175dc5e224c4a18 Mon Sep 17 00:00:00 2001
From: Gyan Sreejith <[email protected]>
Date: Sun, 15 Mar 2026 18:40:15 -0400
Subject: [PATCH v8] Add a new argument -l <logdir> to pg_createsubscriber.

Enabling the option to write messages to log files in the specified directory.
A new directory is created if required. A subdirectory is created with timestamp as its name, and it will contain two new logfiles:
1. pg_createsubscriber_server.log  - captures messages related to starting and stopping the standby server.
2. pg_createsubscriber_internal.log - captures internal diagnostic output from pg_createsubscriber.

For example, if we specify -l abc as an argument, and if the timestamp on running it is 20260119T204317.204, a directory abc is created if it doesn't exist already, with 20260119T204317.204 as its subdirectory and it will contain the two log files pg_createsubscriber_server.log and pg_createsubscriber_internal.log
---
 doc/src/sgml/ref/pg_createsubscriber.sgml     |  22 +++
 src/bin/pg_basebackup/pg_createsubscriber.c   | 165 +++++++++++++++++-
 .../t/040_pg_createsubscriber.pl              |  17 ++
 3 files changed, 201 insertions(+), 3 deletions(-)

diff --git a/doc/src/sgml/ref/pg_createsubscriber.sgml b/doc/src/sgml/ref/pg_createsubscriber.sgml
index cf45ff3573d..67a683e66c7 100644
--- a/doc/src/sgml/ref/pg_createsubscriber.sgml
+++ b/doc/src/sgml/ref/pg_createsubscriber.sgml
@@ -136,6 +136,28 @@ PostgreSQL documentation
      </listitem>
     </varlistentry>
 
+    <varlistentry>
+     <term><option>-l <replaceable class="parameter">directory</replaceable></option></term>
+     <term><option>--logdir=<replaceable class="parameter">directory</replaceable></option></term>
+     <listitem>
+      <para>
+       Specify the name of the log directory. A new directory is created with this name if it does not exist. A subdirectory with a timestamp indicating the time at which pg_createsubscriber was run will be created. The following two log files will be createdin the subdirectory with a umask of 077 so that access is disallowed to other users by default.
+       <itemizedlist>
+        <listitem>
+         <para>
+          pg_createsubscriber_server.log which captures logs related to stopping and starting the standby server,
+         </para>
+        </listitem>
+        <listitem>
+         <para>
+          pg_createsubscriber_internal.log which captures internal diagnostic output (validations, checks, etc.)
+         </para>
+        </listitem>
+       </itemizedlist>
+      </para>
+     </listitem>
+    </varlistentry>
+
     <varlistentry>
      <term><option>-n</option></term>
      <term><option>--dry-run</option></term>
diff --git a/src/bin/pg_basebackup/pg_createsubscriber.c b/src/bin/pg_basebackup/pg_createsubscriber.c
index 2bc84505aab..3495bdb88ce 100644
--- a/src/bin/pg_basebackup/pg_createsubscriber.c
+++ b/src/bin/pg_basebackup/pg_createsubscriber.c
@@ -49,10 +49,14 @@
 #define INCLUDED_CONF_FILE			"pg_createsubscriber.conf"
 #define INCLUDED_CONF_FILE_DISABLED	INCLUDED_CONF_FILE ".disabled"
 
+#define SERVER_LOG_FILE_NAME "pg_createsubscriber_server"
+#define INTERNAL_LOG_FILE_NAME "pg_createsubscriber_internal"
+
 /* Command-line options */
 struct CreateSubscriberOptions
 {
 	char	   *config_file;	/* configuration file */
+	char	   *log_dir;		/* log directory name */
 	char	   *pub_conninfo_str;	/* publisher connection string */
 	char	   *socket_dir;		/* directory for Unix-domain socket, if any */
 	char	   *sub_port;		/* subscriber port number */
@@ -146,6 +150,9 @@ static void drop_existing_subscription(PGconn *conn, const char *subname,
 									   const char *dbname);
 static void get_publisher_databases(struct CreateSubscriberOptions *opt,
 									bool dbnamespecified);
+static void
+			internal_log_file_write(const char *format,...) __attribute__((format(printf, 1, 2)));
+
 
 #define	WAIT_INTERVAL	1		/* 1 second */
 
@@ -167,6 +174,10 @@ static pg_prng_state prng_state;
 static char *pg_ctl_path = NULL;
 static char *pg_resetwal_path = NULL;
 
+static FILE *internal_log_file_fp = NULL;	/* File ptr to log all messages to */
+static char *log_timestamp = NULL;	/* Timestamp to be used in all log file
+									 * names */
+
 /* standby / subscriber data directory */
 static char *subscriber_dir = NULL;
 
@@ -174,6 +185,123 @@ static bool recovery_ended = false;
 static bool standby_running = false;
 static bool recovery_params_set = false;
 
+#undef pg_log_info
+#define pg_log_info(...) do{\
+	if (internal_log_file_fp != NULL) \
+		internal_log_file_write(__VA_ARGS__); \
+	else \
+		pg_log_generic(PG_LOG_INFO, PG_LOG_PRIMARY, __VA_ARGS__);\
+} while(0)
+
+#undef pg_log_info_hint
+#define pg_log_info_hint(...) do{\
+	if (internal_log_file_fp != NULL) \
+		internal_log_file_write(__VA_ARGS__); \
+	else \
+		pg_log_generic(PG_LOG_INFO, PG_LOG_HINT, __VA_ARGS__);\
+} while(0)
+
+#undef pg_log_debug
+#define pg_log_debug(...) do{\
+	if (internal_log_file_fp != NULL) \
+		internal_log_file_write(__VA_ARGS__); \
+	else \
+		if (unlikely(__pg_log_level <= PG_LOG_DEBUG)) \
+			pg_log_generic(PG_LOG_DEBUG, PG_LOG_PRIMARY, __VA_ARGS__); \
+} while(0)
+
+#undef pg_fatal
+#define pg_fatal(...) do{\
+	if (internal_log_file_fp != NULL) \
+		internal_log_file_write(__VA_ARGS__); \
+	pg_log_generic(PG_LOG_ERROR, PG_LOG_PRIMARY, __VA_ARGS__); \
+	exit(1); \
+} while(0)
+
+static void
+internal_log_file_write(const char *format,...)
+{
+	if (internal_log_file_fp != NULL)
+	{
+		va_list		args;
+
+		va_start(args, format);
+		vfprintf(internal_log_file_fp, format, args);
+		fprintf(internal_log_file_fp, "\n");
+		fflush(internal_log_file_fp);
+		va_end(args);
+	}
+}
+
+/*
+ * Open a new logfile with proper permissions.
+ * From src/backend/postmaster/syslogger.c
+ */
+static FILE *
+logfile_open(const char *filename, const char *mode)
+{
+	FILE	   *fh;
+	mode_t		oumask;
+
+	oumask = umask((mode_t) ((~(S_IRUSR | S_IWUSR)) & (S_IRWXU | S_IRWXG | S_IRWXO)));
+	fh = fopen(filename, mode);
+	umask(oumask);
+
+	if (fh)
+	{
+		setvbuf(fh, NULL, PG_IOLBF, 0);
+
+#ifdef WIN32
+		/* use CRLF line endings on Windows */
+		_setmode(_fileno(fh), _O_TEXT);
+#endif
+	}
+	else
+		pg_fatal("could not open log file \"%s\": %m",
+				 filename);
+
+	return fh;
+}
+
+static void
+make_dir(char *dir)
+{
+	struct stat statbuf;
+
+	if (stat(dir, &statbuf) != 0)
+		if (errno == ENOENT)
+		{
+			if (mkdir(dir, S_IRWXU) == 0)
+				pg_log_info("directory %s created", dir);
+			else
+				pg_fatal("could not create log directory \"%s\": %m", dir);
+		}
+}
+
+static void
+make_output_dirs(char *log_dir)
+{
+	char		timestamp[128];
+	struct timeval tval;
+	time_t		now;
+	struct tm	tmbuf;
+	char		timestamp_dir[MAXPGPATH];
+	int			len;
+
+	gettimeofday(&tval, NULL);
+	now = tval.tv_sec;
+	strftime(timestamp, sizeof(timestamp), "%Y%m%dT%H%M%S", localtime_r(&now, &tmbuf));
+	/* append milliseconds */
+	snprintf(timestamp + strlen(timestamp), sizeof(timestamp) - strlen(timestamp),
+			 ".%03u", (unsigned int) (tval.tv_usec / 1000));
+	log_timestamp = pg_strdup(timestamp);
+
+	make_dir(log_dir);
+	len = snprintf(timestamp_dir, MAXPGPATH, "%s/%s", log_dir, timestamp);
+	if (len >= MAXPGPATH)
+		pg_fatal("directory path for log files, %s/%s, is too long", log_dir, timestamp);
+	make_dir(timestamp_dir);
+}
 
 /*
  * Clean up objects created by pg_createsubscriber.
@@ -269,6 +397,12 @@ cleanup_objects_atexit(void)
 
 	if (standby_running)
 		stop_standby_server(subscriber_dir);
+
+	if (internal_log_file_fp != NULL)
+	{
+		fclose(internal_log_file_fp);
+		internal_log_file_fp = NULL;
+	}
 }
 
 static void
@@ -283,6 +417,7 @@ usage(void)
 			 "                                  databases and databases that don't allow connections\n"));
 	printf(_("  -d, --database=DBNAME           database in which to create a subscription\n"));
 	printf(_("  -D, --pgdata=DATADIR            location for the subscriber data directory\n"));
+	printf(_("  -l, --logdir=LOGDIR             location for the new log directory\n"));
 	printf(_("  -n, --dry-run                   dry run, just show what would be done\n"));
 	printf(_("  -p, --subscriber-port=PORT      subscriber port number (default %s)\n"), DEFAULT_SUB_PORT);
 	printf(_("  -P, --publisher-server=CONNSTR  publisher connection string\n"));
@@ -702,6 +837,7 @@ modify_subscriber_sysid(const struct CreateSubscriberOptions *opt)
 	bool		crc_ok;
 	struct timeval tv;
 
+	char	   *out_file;
 	char	   *cmd_str;
 
 	pg_log_info("modifying system identifier of subscriber");
@@ -735,8 +871,14 @@ modify_subscriber_sysid(const struct CreateSubscriberOptions *opt)
 	else
 		pg_log_info("running pg_resetwal on the subscriber");
 
-	cmd_str = psprintf("\"%s\" -D \"%s\" > \"%s\"", pg_resetwal_path,
-					   subscriber_dir, DEVNULL);
+
+	if (opt->log_dir != NULL)
+		out_file = psprintf("%s/%s/%s.log", opt->log_dir, log_timestamp, SERVER_LOG_FILE_NAME);
+	else
+		out_file = DEVNULL;
+
+	cmd_str = psprintf("\"%s\" -D \"%s\" >> \"%s\"", pg_resetwal_path,
+					   subscriber_dir, out_file);
 
 	pg_log_debug("pg_resetwal command is: %s", cmd_str);
 
@@ -1650,6 +1792,9 @@ start_standby_server(const struct CreateSubscriberOptions *opt, bool restricted_
 	if (restrict_logical_worker)
 		appendPQExpBufferStr(pg_ctl_cmd, " -o \"-c max_logical_replication_workers=0\"");
 
+	if (opt->log_dir != NULL)
+		appendPQExpBuffer(pg_ctl_cmd, " -l %s/%s/%s.log", opt->log_dir, log_timestamp, SERVER_LOG_FILE_NAME);
+
 	pg_log_debug("pg_ctl command is: %s", pg_ctl_cmd->data);
 	rc = system(pg_ctl_cmd->data);
 	pg_ctl_status(pg_ctl_cmd->data, rc);
@@ -2181,6 +2326,7 @@ main(int argc, char **argv)
 		{"all", no_argument, NULL, 'a'},
 		{"database", required_argument, NULL, 'd'},
 		{"pgdata", required_argument, NULL, 'D'},
+		{"logdir", required_argument, NULL, 'l'},
 		{"dry-run", no_argument, NULL, 'n'},
 		{"subscriber-port", required_argument, NULL, 'p'},
 		{"publisher-server", required_argument, NULL, 'P'},
@@ -2215,6 +2361,7 @@ main(int argc, char **argv)
 	char	   *consistent_lsn;
 
 	char		pidfile[MAXPGPATH];
+	char	   *internal_log_file;
 
 	pg_logging_init(argv[0]);
 	pg_logging_set_level(PG_LOG_WARNING);
@@ -2239,6 +2386,7 @@ main(int argc, char **argv)
 	/* Default settings */
 	subscriber_dir = NULL;
 	opt.config_file = NULL;
+	opt.log_dir = NULL;
 	opt.pub_conninfo_str = NULL;
 	opt.socket_dir = NULL;
 	opt.sub_port = DEFAULT_SUB_PORT;
@@ -2267,7 +2415,7 @@ main(int argc, char **argv)
 
 	get_restricted_token();
 
-	while ((c = getopt_long(argc, argv, "ad:D:np:P:s:t:TU:v",
+	while ((c = getopt_long(argc, argv, "ad:D:l:np:P:s:t:TU:v",
 							long_options, &option_index)) != -1)
 	{
 		switch (c)
@@ -2288,6 +2436,14 @@ main(int argc, char **argv)
 				subscriber_dir = pg_strdup(optarg);
 				canonicalize_path(subscriber_dir);
 				break;
+			case 'l':
+				opt.log_dir = pg_strdup(optarg);
+				canonicalize_path(opt.log_dir);
+				make_output_dirs(opt.log_dir);
+				internal_log_file = psprintf("%s/%s/%s.log", opt.log_dir, log_timestamp, INTERNAL_LOG_FILE_NAME);
+				if ((internal_log_file_fp = logfile_open(internal_log_file, "a")) == NULL)
+					pg_fatal("could not open log file \"%s\": %m", internal_log_file);
+				break;
 			case 'n':
 				dry_run = true;
 				break;
@@ -2621,5 +2777,8 @@ main(int argc, char **argv)
 
 	pg_log_info("Done!");
 
+	if (internal_log_file_fp != NULL)
+		fclose(internal_log_file_fp);
+
 	return 0;
 }
diff --git a/src/bin/pg_basebackup/t/040_pg_createsubscriber.pl b/src/bin/pg_basebackup/t/040_pg_createsubscriber.pl
index 0c27fca7bb7..3a82f893e28 100644
--- a/src/bin/pg_basebackup/t/040_pg_createsubscriber.pl
+++ b/src/bin/pg_basebackup/t/040_pg_createsubscriber.pl
@@ -14,6 +14,7 @@ program_version_ok('pg_createsubscriber');
 program_options_handling_ok('pg_createsubscriber');
 
 my $datadir = PostgreSQL::Test::Utils::tempdir;
+my $logdir = PostgreSQL::Test::Utils::tempdir + "/logdir";
 
 # Generate a database with a name made of a range of ASCII characters.
 # Extracted from 002_pg_upgrade.pl.
@@ -362,9 +363,25 @@ command_ok(
 		'--subscription' => 'sub2',
 		'--database' => $db1,
 		'--database' => $db2,
+		'--logdir' => $logdir,
 	],
 	'run pg_createsubscriber --dry-run on node S');
 
+# Check that the log files were created
+my @server_log_files = glob "$logdir/*/pg_createsubscriber_server.log";
+is( scalar(@server_log_files), 1, "
+    pg_createsubscriber_server.log file was created");
+my $server_log_file_size = -s shift(@server_log_files);
+isnt($server_log_file_size, 0,
+	"pg_createsubscriber_server.log file not empty");
+
+my @internal_log_files = glob "$logdir/*/pg_createsubscriber_internal.log";
+is( scalar(@internal_log_files), 1, "
+    pg_createsubscriber_internal.log file was created");
+my $internal_log_file_size = -s shift(@internal_log_files);
+isnt($internal_log_file_size, 0,
+	"pg_createsubscriber_internal.log file not empty");
+
 # Check if node S is still a standby
 $node_s->start;
 is($node_s->safe_psql('postgres', 'SELECT pg_catalog.pg_is_in_recovery()'),
-- 
2.43.0

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