I have included the patch file after making the changes to the SGML docs.
Thanks for your help,
Gyan Sreejith
On Thu, Dec 11, 2025 at 8:33 PM Gyan Sreejith <[email protected]>
wrote:
> Thanks for the feedback, Peter.
>
> I am currently working on the SGML docs update, and will promptly get back
> with an update.
>
> For your second point, currently, all output goes directly to the console.
> I thought it made more sense to break it up into multiple files depending
> on what was being invoked. Do you have another opinion?
>
> Thank you once again,
> Gyan Sreejith
>
> On Thu, Dec 11, 2025 at 2:29 AM Peter Smith <[email protected]> wrote:
>
>> On Wed, Dec 10, 2025 at 9:17 AM Gyan Sreejith <[email protected]>
>> wrote:
>> >
>> > Background:
>> >
>> > pg_createsubscriber currently outputs all messages (internal validation
>> messages, standby server start/stop logs, recovery progress output, and
>> output from utilities) directly to the console. As a result, users may find
>> debugging and handling errors difficult. It would be more convenient if
>> messages were separated and stored in different log files. There is already
>> a similar implementation in pg_upgrade.
>> >
>> > Proposed Solution:
>> >
>> > Based on issues mentioned previously, I would like to propose a new
>> argument -l <logdir> which can be specified for pg_createsubscriber. Using
>> it would create the following log files:
>> >
>> > logdir/pg_createsubscriber_server.log which captures all logs related
>> to starting and stopping the standby server.
>> >
>> > logdir/pg_createsubscriber_resetwal.log which captures the output of
>> pg_resetwal
>> >
>> > logdir/pg_createsubscriber_internal.log which captures internal
>> diagnostic output from pg_createsubscriber (validations, checks, etc.)
>> >
>> > Overall, this proposed solution could make the pg_createsubscriber
>> command output messages more organized. The command would be easier to use
>> as users will only have to read individual log files rather than parse
>> through lots of possibly irrelevant output messages. I have attached the
>> patch for this change.
>> >
>> > Special thanks to Vignesh C. for his offlist guidance on this project.
>> >
>> >
>> > Regards, Gyan Sreejith
>> >
>>
>> Hi Gyan.
>>
>> I haven't yet looked at this patch in any detail, but here are some
>> quick comments:
>>
>> ======
>>
>> 1.
>> + printf(_(" -l, --logdir=LOGDIR location for the new log
>> directory\n"));
>>
>> The patch is missing SGML docs updates for pg_createsubscriber new
>> option, and any explanation of the split of logfiles.
>>
>> 2.
>> I might be mistaken, but IIUC it seems the splitting of the logfile
>> only works when --logdir is specified. Is that correct?
>> Why should --logdir have any side-effect other than assigning the log
>> destination folder?
>>
>> ======
>> Kind Regards,
>> Peter Smith.
>> Fujitsu Australia
>>
>
diff --git a/doc/src/sgml/ref/pg_createsubscriber.sgml b/doc/src/sgml/ref/pg_createsubscriber.sgml
index bb9cc72576c..5e24a297566 100644
--- a/doc/src/sgml/ref/pg_createsubscriber.sgml
+++ b/doc/src/sgml/ref/pg_createsubscriber.sgml
@@ -136,6 +136,33 @@ 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>
+ The target directory in which the following three log files will be created:
+ <itemizedlist>
+ <listitem>
+ <para>
+ pg_createsubscriber_server.log which captures logs related to stopping and starting the standby server,
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ pg_createsubscriber_resetwal.log which captures the output of pg_resetwal, and
+ </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 f59c293d875..e8d7b0730e9 100644
--- a/src/bin/pg_basebackup/pg_createsubscriber.c
+++ b/src/bin/pg_basebackup/pg_createsubscriber.c
@@ -36,6 +36,7 @@
struct CreateSubscriberOptions
{
char *config_file; /* configuration file */
+ char *log_dir; /* log directory */
char *pub_conninfo_str; /* publisher connection string */
char *socket_dir; /* directory for Unix-domain socket, if any */
char *sub_port; /* subscriber port number */
@@ -150,6 +151,8 @@ static pg_prng_state prng_state;
static char *pg_ctl_path = NULL;
static char *pg_resetwal_path = NULL;
+static char *internal_log_file = NULL;
+
/* standby / subscriber data directory */
static char *subscriber_dir = NULL;
@@ -251,6 +254,7 @@ 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"));
@@ -670,6 +674,7 @@ 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");
@@ -703,8 +708,14 @@ modify_subscriber_sysid(const struct CreateSubscriberOptions *opt)
else
pg_log_info("running pg_resetwal on the subscriber");
+
+ if (opt->log_dir != NULL)
+ out_file = psprintf("%s/pg_createsubscriber_resetwal.log", opt->log_dir);
+ else
+ out_file = DEVNULL;
+
cmd_str = psprintf("\"%s\" -D \"%s\" > \"%s\"", pg_resetwal_path,
- subscriber_dir, DEVNULL);
+ subscriber_dir, out_file);
pg_log_debug("pg_resetwal command is: %s", cmd_str);
@@ -893,8 +904,18 @@ check_publisher(const struct LogicalRepInfo *dbinfo)
int cur_walsenders;
int max_prepared_transactions;
char *max_slot_wal_keep_size;
+ FILE *fp;
- pg_log_info("checking settings on publisher");
+ if (internal_log_file != NULL)
+ {
+ if ((fp = fopen(internal_log_file, "a")) == NULL)
+ pg_fatal("could not write to log file \"%s\": %m", internal_log_file);
+
+ fprintf(fp, "checking settings on publisher\n");
+ fclose(fp);
+ }
+ else
+ pg_log_info("checking settings on publisher");
conn = connect_database(dbinfo[0].pubconninfo, true);
@@ -1028,8 +1049,18 @@ check_subscriber(const struct LogicalRepInfo *dbinfo)
int max_lrworkers;
int max_reporigins;
int max_wprocs;
+ FILE *fp;
- pg_log_info("checking settings on subscriber");
+ if (internal_log_file != NULL)
+ {
+ if ((fp = fopen(internal_log_file, "a")) == NULL)
+ pg_fatal("could not write to log file \"%s\": %m", internal_log_file);
+
+ fprintf(fp, "checking settings on subscriber\n");
+ fclose(fp);
+ }
+ else
+ pg_log_info("checking settings on subscriber");
conn = connect_database(dbinfo[0].subconninfo, true);
@@ -1548,6 +1579,11 @@ 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/pg_createsubscriber_server.log", opt->log_dir);
+ }
+
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);
@@ -2071,6 +2107,7 @@ 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'},
@@ -2129,6 +2166,7 @@ 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;
@@ -2157,7 +2195,7 @@ 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)
@@ -2178,6 +2216,23 @@ 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);
+
+ if (stat(opt.log_dir, &statbuf) != 0)
+ {
+ if (errno == ENOENT)
+ {
+ mkdir(opt.log_dir, S_IRWXU);
+ pg_log_info("log directory created");
+ }
+ else
+ pg_fatal("could not access directory \"%s\": %m", opt.log_dir);
+ }
+
+ internal_log_file = psprintf("%s/pg_createsubscriber_internal.log", opt.log_dir);
+ break;
case 'n':
dry_run = true;
break;
diff --git a/src/bin/pg_basebackup/t/040_pg_createsubscriber.pl b/src/bin/pg_basebackup/t/040_pg_createsubscriber.pl
index 3d6086dc489..1712adc0439 100644
--- 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";
+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.
@@ -537,10 +538,43 @@ my $sysid_s = $node_s->safe_psql('postgres',
'SELECT system_identifier FROM pg_control_system()');
isnt($sysid_p, $sysid_s, 'system identifier was changed');
+$node_p->backup('backup_3');
+
+# Set up node R as a logical replica node
+my $node_r = PostgreSQL::Test::Cluster->new('node_r');
+$node_r->init_from_backup($node_p, 'backup_3', has_streaming => 1);
+$node_r->append_conf(
+ 'postgresql.conf', qq[
+primary_conninfo = '$pconnstr dbname=postgres'
+hot_standby_feedback = on
+]);
+$node_r->set_standby_mode();
+
+# Test that --logdir works for pg_createsubscriber
+command_ok(
+ [
+ 'pg_createsubscriber',
+ '--verbose',
+ '--pgdata' => $node_r->data_dir,
+ '--publisher-server' => $pconnstr,
+ '--database' => 'postgres',
+ '--logdir' => $logdir,
+ ],
+ 'check for log file creation for pg_createSubscriber');
+
+# Check that all log files were created
+ok( -f "$logdir/pg_createsubscriber_server.log",
+ 'pg_createsubscriber_server.log file was created');
+ok(-f "$logdir/pg_createsubscriber_resetwal.log",
+ 'pg_resetwal.log file was created');
+ok( -f "$logdir/pg_createsubscriber_internal.log",
+ 'pg_createsubsriber.log file was created');
+
# clean up
$node_p->teardown_node;
$node_s->teardown_node;
$node_t->teardown_node;
$node_f->teardown_node;
+$node_r->teardown_node;
done_testing();
