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help / color / mirror / Atom feedFrom: Gyan Sreejith <[email protected]>
To: Amit Kapila <[email protected]>
Cc: Euler Taveira <[email protected]>
Cc: vignesh C <[email protected]>
Cc: [email protected] <[email protected]>
Cc: [email protected] <[email protected]>
Cc: Peter Smith <[email protected]>
Subject: Re: [Proposal] Adding Log File Capability to pg_createsubscriber
Date: Mon, 9 Mar 2026 18:55:56 -0400
Message-ID: <CAEqnbaU50vLy031AbvmfXJ3_qv9iS4pVaMdmsnmpF87r=EqW7Q@mail.gmail.com> (raw)
In-Reply-To: <CAA4eK1+jd6zH-LL8FOrw01chrNetRoZGKXSqV7GNo_--UXYc_w@mail.gmail.com>
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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.
Regarding duplicating code - I was trying to keep the change contained. Is
it okay to make that change in a separate check in since it would also
touch src/backend/postmaster/syslogger.c?
Thank you!
Gyan Sreejith
On Fri, Mar 6, 2026 at 5:51 AM Amit Kapila <[email protected]> wrote:
> On Thu, Mar 5, 2026 at 8:19 PM Euler Taveira <[email protected]> wrote:
> >
> > One of the arguments to have this feature was that pg_createsubscriber
> mixes the
> > server and tool messages. Couldn't we fix it adding "marks" on the
> output saying
> > the server log messages starts here and the server log messages ends
> here?
> >
>
> It will simplify the output to some extent but still it will be mixed
> at different intervals in the LOG which is not good for grepping
> required info. Also, I am not sure if we use such markers at other
> places.
>
> --
> With Regards,
> Amit Kapila.
>
Attachments:
[application/octet-stream] v7-0001-Add-a-new-argument-l-logdir-to-pg_createsubscribe.patch (12.6K, 3-v7-0001-Add-a-new-argument-l-logdir-to-pg_createsubscribe.patch)
download | inline diff:
From 862ba2419febe70c581631478677f7f083478115 Mon Sep 17 00:00:00 2001
From: Gyan Sreejith <[email protected]>
Date: Sun, 8 Mar 2026 20:06:49 -0400
Subject: [PATCH v7] 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 | 167 +++++++++++++++++-
.../t/040_pg_createsubscriber.pl | 12 +-
3 files changed, 197 insertions(+), 4 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..c152467b09a 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 +1792,11 @@ 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/%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 +2328,7 @@ 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 +2363,7 @@ 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 +2388,7 @@ 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 +2417,7 @@ 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 +2438,14 @@ 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 +2779,8 @@ 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..7a4b9ca433a 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.
@@ -362,9 +363,18 @@ 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 @internal_log_files = glob "$logdir/*/pg_createsubscriber_internal.log";
+is( scalar(@internal_log_files), 1, "
+ pg_createsubscriber_internal.log file was created");
+
# 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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Subject: Re: [Proposal] Adding Log File Capability to pg_createsubscriber
In-Reply-To: <CAEqnbaU50vLy031AbvmfXJ3_qv9iS4pVaMdmsnmpF87r=EqW7Q@mail.gmail.com>
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