Remove the custom_variable_classes parameter.

This variable provides only marginal error-prevention capability (since
it can only check the prefix of a qualified GUC name), and the consensus
is that that isn't worth the amount of hassle that maintaining the setting
creates for DBAs.  So, let's just remove it.

With this commit, the system will silently accept a value for any qualified
GUC name at all, whether it has anything to do with any known extension or
not.  (Unqualified names still have to match known built-in settings,
though; and you will get a WARNING at extension load time if there's an
unrecognized setting with that extension's prefix.)

There's still some discussion ongoing about whether to tighten that up and
if so how; but if we do come up with a solution, it's not likely to look
anything like custom_variable_classes.

1 files changed, 11 insertions, 103 deletions

diff --git a/src/backend/utils/misc/guc-file.l b/src/backend/utils/misc/guc-file.l
index a7cf0378dc..7728544c54 100644
--- a/src/backend/utils/misc/guc-file.l
+++ b/src/backend/utils/misc/guc-file.l
@@ -111,8 +111,6 @@ ProcessConfigFile(GucContext context)
 	ConfigVariable *item,
 				   *head,
 				   *tail;
-	char	   *cvc = NULL;
-	struct config_string *cvc_struct;
 	int			i;
 
 	/*
@@ -139,50 +137,6 @@ ProcessConfigFile(GucContext context)
 	}
 
 	/*
-	 * We need the proposed new value of custom_variable_classes to check
-	 * custom variables with.  ParseConfigFile ensured that if it's in
-	 * the file, it's first in the list.  But first check to see if we
-	 * have an active value from the command line, which should override
-	 * the file in any case.  (Since there's no relevant env var, the
-	 * only possible nondefault sources are the file and ARGV.)
-	 */
-	cvc_struct = (struct config_string *)
-		find_option("custom_variable_classes", false, elevel);
-	Assert(cvc_struct);
-	if (cvc_struct->gen.reset_source > PGC_S_FILE)
-	{
-		cvc = guc_strdup(elevel, cvc_struct->reset_val);
-		if (cvc == NULL)
-		{
-			error = true;
-			goto cleanup_list;
-		}
-	}
-	else if (head != NULL &&
-			 guc_name_compare(head->name, "custom_variable_classes") == 0)
-	{
-		/*
-		 * Need to canonicalize the value by calling the check hook.
-		 */
-		void   *extra = NULL;
-
-		cvc = guc_strdup(elevel, head->value);
-		if (cvc == NULL)
-		{
-			error = true;
-			goto cleanup_list;
-		}
-		if (!call_string_check_hook(cvc_struct, &cvc, &extra,
-									PGC_S_FILE, elevel))
-		{
-			error = true;
-			goto cleanup_list;
-		}
-		if (extra)
-			free(extra);
-	}
-
-	/*
 	 * Mark all extant GUC variables as not present in the config file.
 	 * We need this so that we can tell below which ones have been removed
 	 * from the file since we last processed it.
@@ -199,39 +153,29 @@ ProcessConfigFile(GucContext context)
 	 * quasi-syntactic check on the validity of the config file.  It is
 	 * important that the postmaster and all backends agree on the results
 	 * of this phase, else we will have strange inconsistencies about which
-	 * processes accept a config file update and which don't.  Hence, custom
-	 * variable names can only be checked against custom_variable_classes,
-	 * not against any loadable modules that might (or might not) be present.
-	 * Likewise, we don't attempt to validate the options' values here.
+	 * processes accept a config file update and which don't.  Hence, unknown
+	 * custom variable names have to be accepted without complaint.  For the
+	 * same reason, we don't attempt to validate the options' values here.
 	 *
 	 * In addition, the GUC_IS_IN_FILE flag is set on each existing GUC
 	 * variable mentioned in the file.
 	 */
 	for (item = head; item; item = item->next)
 	{
-		char   *sep = strchr(item->name, GUC_QUALIFIER_SEPARATOR);
 		struct config_generic *record;
 
-		if (sep)
-		{
-			/* Custom variable, so check against custom_variable_classes */
-			if (!is_custom_class(item->name, sep - item->name, cvc))
-			{
-				ereport(elevel,
-						(errcode(ERRCODE_UNDEFINED_OBJECT),
-						 errmsg("unrecognized configuration parameter \"%s\" in file \"%s\" line %u",
-								item->name,
-								item->filename, item->sourceline)));
-				error = true;
-				continue;
-			}
-		}
-
+		/*
+		 * Try to find the variable; but do not create a custom placeholder
+		 * if it's not there already.
+		 */
 		record = find_option(item->name, false, elevel);
 
 		if (record)
+		{
+			/* Found, so mark it as present in file */
 			record->status |= GUC_IS_IN_FILE;
-		else if (!sep)
+		}
+		else if (strchr(item->name, GUC_QUALIFIER_SEPARATOR) == NULL)
 		{
 			/* Invalid non-custom variable, so complain */
 			ereport(elevel,
@@ -382,8 +326,6 @@ ProcessConfigFile(GucContext context)
 
  cleanup_list:
 	FreeConfigVariables(head);
-	if (cvc)
-		free(cvc);
 
 	if (error)
 	{
@@ -581,40 +523,6 @@ ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
 			pfree(opt_name);
 			pfree(opt_value);
 		}
-		else if (guc_name_compare(opt_name, "custom_variable_classes") == 0)
-		{
-			/*
-			 * This variable must be processed first as it controls
-			 * the validity of other variables; so it goes at the head
-			 * of the result list.  If we already found a value for it,
-			 * replace with this one.
-			 */
-			item = *head_p;
-			if (item != NULL &&
-				guc_name_compare(item->name, "custom_variable_classes") == 0)
-			{
-				/* replace existing head item */
-				pfree(item->name);
-				pfree(item->value);
-				item->name = opt_name;
-				item->value = opt_value;
-				item->filename = pstrdup(config_file);
-				item->sourceline = ConfigFileLineno-1;
-			}
-			else
-			{
-				/* prepend to list */
-				item = palloc(sizeof *item);
-				item->name = opt_name;
-				item->value = opt_value;
-				item->filename = pstrdup(config_file);
-				item->sourceline = ConfigFileLineno-1;
-				item->next = *head_p;
-				*head_p = item;
-				if (*tail_p == NULL)
-					*tail_p = item;
-			}
-		}
 		else
 		{
 			/* ordinary variable, append to list */