Allow the postmaster to accept changes in PGC_BACKEND GUC variables

from the config file, so that these changes will propagate to backends
started later.  Already-started backends continue to ignore changes
in these variables.

diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml
index 6afdd9c9637e2fe2814a399e6b2ce0ce16d466ab..19ed4a45c84a5ac19fc750765f67f62dc85cc1bc 100644 (file)
--- a/doc/src/sgml/runtime.sgml
+++ b/doc/src/sgml/runtime.sgml
@@ -1,5 +1,5 @@
 
 
 
@@ -845,10 +845,11 @@ env PGOPTIONS='-c geqo=off' psql
       LOG_CONNECTIONS (boolean)
       
        
-        Prints a line informing about each successful connection to
+        Prints a line informing about each successful connection in
         the server log. This is off by default, although it is
         probably very useful. This option can only be set at server
-        start.
+        start or in the postgresql.conf
+        configuration file.
        
       
      
@@ -1223,7 +1224,7 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir'
       
        
         Sets the maximum number of simultaneously open files in each server
-   process.  The default is 1000.  The limit actually used by the code
+   subprocess.  The default is 1000.  The limit actually used by the code
    is the smaller of this setting and the result of
    sysconf(_SC_OPEN_MAX).
    Therefore, on systems where sysconf returns a reasonable limit,
@@ -1233,7 +1234,10 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir'
    processes all try to open that many files.  If you find yourself
    seeing Too many open files failures, try reducing this
    setting.
-        This option can only be set at server start.
+        This option can only be set at server start or in the
+   postgresql.conf configuration file;
+   if changed in the configuration file, it only affects
+   subsequently-started server subprocesses.
        
       
      

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index c8a9a0afc28362e58555617945f43a6f7d40d693..c506e3147cdb9ce5f76771d6ff0e7cfb8c17c579 100644 (file)
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -4,7 +4,7 @@
  * Support for grand unified configuration scheme, including SET
  * command, configuration file, and command line options.
  *
- * $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.54 2001/09/30 18:57:45 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.55 2001/09/30 20:16:21 tgl Exp $
  *
  * Copyright 2000 by PostgreSQL Global Development Group
  * Written by Peter Eisentraut .
@@ -704,37 +704,49 @@ set_config_option(const char *name, const char *value,
     * precise rules. Note that we don't want to throw errors if we're in
     * the SIGHUP context. In that case we just ignore the attempt.
     */
-   if (record->context == PGC_POSTMASTER && context != PGC_POSTMASTER)
+   switch (record->context)
    {
-       if (context != PGC_SIGHUP)
-           elog(ERROR, "'%s' cannot be changed after server start", name);
-       else
-           return true;
-   }
-   else if (record->context == PGC_SIGHUP && context != PGC_SIGHUP &&
-            context != PGC_POSTMASTER)
-   {
-       elog(ERROR, "'%s' cannot be changed now", name);
-
-       /*
-        * Hmm, the idea of the SIGHUP context is "ought to be global, but
-        * can be changed after postmaster start". But there's nothing
-        * that prevents a crafty administrator from sending SIGHUP
-        * signals to individual backends only.
-        */
-   }
-   else if (record->context == PGC_BACKEND && context != PGC_BACKEND
-            && context != PGC_POSTMASTER)
-   {
-       if (context != PGC_SIGHUP)
-           elog(ERROR, "'%s' cannot be set after connection start", name);
-       else
-           return true;
+       case PGC_POSTMASTER:
+           if (context == PGC_SIGHUP)
+               return true;
+           if (context != PGC_POSTMASTER)
+               elog(ERROR, "'%s' cannot be changed after server start", name);
+           break;
+       case PGC_SIGHUP:
+           if (context != PGC_SIGHUP && context != PGC_POSTMASTER)
+               elog(ERROR, "'%s' cannot be changed now", name);
+           /*
+            * Hmm, the idea of the SIGHUP context is "ought to be global, but
+            * can be changed after postmaster start". But there's nothing
+            * that prevents a crafty administrator from sending SIGHUP
+            * signals to individual backends only.
+            */
+           break;
+       case PGC_BACKEND:
+           if (context == PGC_SIGHUP)
+           {
+               /*
+                * If a PGC_BACKEND parameter is changed in the config file,
+                * we want to accept the new value in the postmaster (whence
+                * it will propagate to subsequently-started backends), but
+                * ignore it in existing backends.  This is a tad klugy, but
+                * necessary because we don't re-read the config file during
+                * backend start.
+                */
+               if (IsUnderPostmaster)
+                   return true;
+           }
+           else if (context != PGC_BACKEND && context != PGC_POSTMASTER)
+               elog(ERROR, "'%s' cannot be set after connection start", name);
+           break;
+       case PGC_SUSET:
+           if (context == PGC_USERSET || context == PGC_BACKEND)
+               elog(ERROR, "permission denied");
+           break;
+       case PGC_USERSET:
+           /* always okay */
+           break;
    }
-   else if (record->context == PGC_SUSET &&
-            (context == PGC_USERSET || context == PGC_BACKEND))
-       elog(ERROR, "permission denied");
-
 
    /*
     * Evaluate value and set variable

diff --git a/src/include/utils/guc.h b/src/include/utils/guc.h
index 8909320718c52f344a9e4dc1699ae32f44f52e26..176fa7c8933218e26d2d38b4edbd87a66cfb9cbf 100644 (file)
--- a/src/include/utils/guc.h
+++ b/src/include/utils/guc.h
@@ -4,7 +4,7 @@
  * External declarations pertaining to backend/utils/misc/guc.c and
  * backend/utils/misc/guc-file.l
  *
- * $Id: guc.h,v 1.9 2001/06/18 16:14:43 momjian Exp $
+ * $Id: guc.h,v 1.10 2001/09/30 20:16:21 tgl Exp $
  */
 #ifndef GUC_H
 #define GUC_H
@@ -23,11 +23,12 @@
  * certain point in their main loop. It's safer to wait than to read a
  * file asynchronously.)
  *
- * BACKEND options can only be set at postmaster startup or with the
- * PGOPTIONS variable from the client when the connection is
- * initiated. Note that you cannot change this kind of option using
- * the SIGHUP mechanism, that would defeat the purpose of this being
- * fixed for a given backend once started.
+ * BACKEND options can only be set at postmaster startup, from the
+ * configuration file, or with the PGOPTIONS variable from the client
+ * when the connection is initiated.  Furthermore, an already-started
+ * backend will ignore changes to such an option in the configuration
+ * file.  The idea is that these options are fixed for a given backend
+ * once it's started, but they can vary across backends.
  *
  * SUSET options can be set at postmaster startup, with the SIGHUP
  * mechanism, or from SQL if you're a superuser. These options cannot