If the stats collector dies during Hot Standby, restart it.

This bug exists as far back as 9.0, when Hot Standby was introduced,
so back-patch to all supported branches.

Report and patch by Takayuki Tsunakawa, reviewed by Michael Paquier
and Kuntal Ghosh.

diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 2d43506cd0e362fee067fd1c3126fe8a29f6acbc..24add74512fa2086d0044c6fc12dfbdbe7d776a3 100644 (file)
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -1753,7 +1753,8 @@ ServerLoop(void)
        }
 
        /* If we have lost the stats collector, try to start a new one */
-       if (PgStatPID == 0 && pmState == PM_RUN)
+       if (PgStatPID == 0 &&
+           (pmState == PM_RUN || pmState == PM_HOT_STANDBY))
            PgStatPID = pgstat_start();
 
        /* If we have lost the archiver, try to start a new one. */
@@ -2963,7 +2964,7 @@ reaper(SIGNAL_ARGS)
            if (!EXIT_STATUS_0(exitstatus))
                LogChildExit(LOG, _("statistics collector process"),
                             pid, exitstatus);
-           if (pmState == PM_RUN)
+           if (pmState == PM_RUN || pmState == PM_HOT_STANDBY)
                PgStatPID = pgstat_start();
            continue;
        }