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 09f50bf4942993dc9fc9e14121d316c9d8a98a08..f3e723230c9b11c83f8237b7873e948a76be0673 100644 (file)
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -1754,7 +1754,8 @@ ServerLoop(void)
            PgArchPID = pgarch_start();
 
        /* 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 need to signal the autovacuum launcher, do so now */
@@ -2902,7 +2903,7 @@ 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;
        }