Fix processing of PGC_BACKEND GUC parameters on Windows.

EXEC_BACKEND builds (i.e., Windows) failed to absorb values of PGC_BACKEND
parameters if they'd been changed post-startup via the config file.  This
for example prevented log_connections from working if it were turned on
post-startup.  The mechanism for handling this case has always been a bit
of a kluge, and it wasn't revisited when we implemented EXEC_BACKEND.
While in a normal forking environment new backends will inherit the
postmaster's value of such settings, EXEC_BACKEND backends have to read
the settings from the CONFIG_EXEC_PARAMS file, and they were mistakenly
rejecting them.  So this case has always been broken in the Windows port;
so back-patch to all supported branches.

Amit Kapila

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index f340214f1d4d2bbf790b0568373dca5cc8cb2f3e..4377ff555fc68e4383e70a9599072f3f44c4c083 100644 (file)
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -4625,9 +4625,23 @@ set_config_option(const char *name, const char *value,
                                 * ignore it in existing backends.      This is a tad klugy, but
                                 * necessary because we don't re-read the config file during
                                 * backend start.
+                                *
+                                * In EXEC_BACKEND builds, this works differently: we load all
+                                * nondefault settings from the CONFIG_EXEC_PARAMS file during
+                                * backend start.  In that case we must accept PGC_SIGHUP
+                                * settings, so as to have the same value as if we'd forked
+                                * from the postmaster.  We detect this situation by checking
+                                * IsInitProcessingMode, which is a bit ugly, but it doesn't
+                                * seem worth passing down an explicit flag saying we're doing
+                                * read_nondefault_variables().
                                 */
+#ifdef EXEC_BACKEND
+                               if (IsUnderPostmaster && !IsInitProcessingMode())
+                                       return true;
+#else
                                if (IsUnderPostmaster)
                                        return true;
+#endif
                        }
                        else if (context != PGC_BACKEND && context != PGC_POSTMASTER)
                        {
@@ -6918,6 +6932,12 @@ read_nondefault_variables(void)
        int                     varsourceline;
        GucSource       varsource;
 
+       /*
+        * Assert that PGC_BACKEND case in set_config_option() will do the right
+        * thing.
+        */
+       Assert(IsInitProcessingMode());
+
        /*
         * Open file
         */