diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index bbf725dfbc5aa58a5b43f15998e2c0424906ecfb..bfef707050a82f7842b1e2da550efcfa4882ec82 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -441,6 +441,7 @@ typedef struct
 	pid_t		PostmasterPid;
 	TimestampTz PgStartTime;
 	TimestampTz PgReloadTime;
+	pg_time_t	first_syslogger_file_time;
 	bool		redirection_done;
 	bool		IsBinaryUpgrade;
 	int			max_safe_fds;
@@ -4701,7 +4702,7 @@ MaxLivePostmasterChildren(void)
 
 /*
  * The following need to be available to the save/restore_backend_variables
- * functions
+ * functions.  They are marked NON_EXEC_STATIC in their home modules.
  */
 extern slock_t *ShmemLock;
 extern LWLock *LWLockArray;
@@ -4709,6 +4710,7 @@ extern slock_t *ProcStructLock;
 extern PGPROC *AuxiliaryProcs;
 extern PMSignalData *PMSignalState;
 extern pgsocket pgStatSock;
+extern pg_time_t first_syslogger_file_time;
 
 #ifndef WIN32
 #define write_inheritable_socket(dest, src, childpid) ((*(dest) = (src)), true)
@@ -4761,6 +4763,7 @@ save_backend_variables(BackendParameters *param, Port *port,
 	param->PostmasterPid = PostmasterPid;
 	param->PgStartTime = PgStartTime;
 	param->PgReloadTime = PgReloadTime;
+	param->first_syslogger_file_time = first_syslogger_file_time;
 
 	param->redirection_done = redirection_done;
 	param->IsBinaryUpgrade = IsBinaryUpgrade;
@@ -4985,6 +4988,7 @@ restore_backend_variables(BackendParameters *param, Port *port)
 	PostmasterPid = param->PostmasterPid;
 	PgStartTime = param->PgStartTime;
 	PgReloadTime = param->PgReloadTime;
+	first_syslogger_file_time = param->first_syslogger_file_time;
 
 	redirection_done = param->redirection_done;
 	IsBinaryUpgrade = param->IsBinaryUpgrade;
diff --git a/src/backend/postmaster/syslogger.c b/src/backend/postmaster/syslogger.c
index 919cc49fa945f27642f8723fefec486cc6657478..0febf64d87f2b337b70e4c9e49d4399b6aa03c0e 100644
--- a/src/backend/postmaster/syslogger.c
+++ b/src/backend/postmaster/syslogger.c
@@ -2,7 +2,7 @@
  *
  * syslogger.c
  *
- * The system logger (syslogger) is new in Postgres 8.0. It catches all
+ * The system logger (syslogger) appeared in Postgres 8.0. It catches all
  * stderr output from the postmaster, backends, and other subprocesses
  * by redirecting to a pipe, and writes it to a set of logfiles.
  * It's possible to have size and age limits for the logfile configured
@@ -91,6 +91,7 @@ static bool pipe_eof_seen = false;
 static bool rotation_disabled = false;
 static FILE *syslogFile = NULL;
 static FILE *csvlogFile = NULL;
+NON_EXEC_STATIC pg_time_t first_syslogger_file_time = 0;
 static char *last_file_name = NULL;
 static char *last_csv_file_name = NULL;
 static Latch sysLoggerLatch;
@@ -291,6 +292,13 @@ SysLoggerMain(int argc, char *argv[])
 		elog(FATAL, "could not create syslogger data transfer thread: %m");
 #endif   /* WIN32 */
 
+	/*
+	 * Remember active logfile's name.  We recompute this from the reference
+	 * time because passing down just the pg_time_t is a lot cheaper than
+	 * passing a whole file path in the EXEC_BACKEND case.
+	 */
+	last_file_name = logfile_getname(first_syslogger_file_time, NULL);
+
 	/* remember active logfile parameters */
 	currentLogDir = pstrdup(Log_directory);
 	currentLogFilename = pstrdup(Log_filename);
@@ -560,9 +568,18 @@ SysLogger_Start(void)
 
 	/*
 	 * The initial logfile is created right in the postmaster, to verify that
-	 * the Log_directory is writable.
+	 * the Log_directory is writable.  We save the reference time so that
+	 * the syslogger child process can recompute this file name.
+	 *
+	 * It might look a bit strange to re-do this during a syslogger restart,
+	 * but we must do so since the postmaster closed syslogFile after the
+	 * previous fork (and remembering that old file wouldn't be right anyway).
+	 * Note we always append here, we won't overwrite any existing file.  This
+	 * is consistent with the normal rules, because by definition this is not
+	 * a time-based rotation.
 	 */
-	filename = logfile_getname(time(NULL), NULL);
+	first_syslogger_file_time = time(NULL);
+	filename = logfile_getname(first_syslogger_file_time, NULL);
 
 	syslogFile = logfile_open(filename, "a", false);
 
@@ -1046,8 +1063,12 @@ pipeThread(void *arg)
 #endif   /* WIN32 */
 
 /*
- * open the csv log file - we do this opportunistically, because
+ * Open the csv log file - we do this opportunistically, because
  * we don't know if CSV logging will be wanted.
+ *
+ * This is only used the first time we open the csv log in a given syslogger
+ * process, not during rotations.  As with opening the main log file, we
+ * always append in this situation.
  */
 static void
 open_csvlogfile(void)
@@ -1058,7 +1079,10 @@ open_csvlogfile(void)
 
 	csvlogFile = logfile_open(filename, "a", false);
 
-	pfree(filename);
+	if (last_csv_file_name != NULL)		/* probably shouldn't happen */
+		pfree(last_csv_file_name);
+
+	last_csv_file_name = filename;
 }
 
 /*
@@ -1137,14 +1161,7 @@ logfile_rotate(bool time_based_rotation, int size_rotation_for)
 	 * elapsed time and not something else, and (c) the computed file name is
 	 * different from what we were previously logging into.
 	 *
-	 * Note: during the first rotation after forking off from the postmaster,
-	 * last_file_name will be NULL.  (We don't bother to set it in the
-	 * postmaster because it ain't gonna work in the EXEC_BACKEND case.) So we
-	 * will always append in that situation, even though truncating would
-	 * usually be safe.
-	 *
-	 * For consistency, we treat CSV logs the same even though they aren't
-	 * opened in the postmaster.
+	 * Note: last_file_name should never be NULL here, but if it is, append.
 	 */
 	if (time_based_rotation || (size_rotation_for & LOG_DESTINATION_STDERR))
 	{