Support ALTER SYSTEM RESET command.

This patch allows us to execute ALTER SYSTEM RESET command to
remove the configuration entry from postgresql.auto.conf.

Vik Fearing, reviewed by Amit Kapila and me.

diff --git a/doc/src/sgml/ref/alter_system.sgml b/doc/src/sgml/ref/alter_system.sgml
index 23c30efc8f853df9eb4652e45836df200ef95bfb..a6e32106e80206b2c58ac546092c083c3a40d319 100644 (file)
--- a/doc/src/sgml/ref/alter_system.sgml
+++ b/doc/src/sgml/ref/alter_system.sgml
@@ -22,6 +22,9 @@ PostgreSQL documentation
  <refsynopsisdiv>
 <synopsis>
 ALTER SYSTEM SET <replaceable class="PARAMETER">configuration_parameter</replaceable> { TO | = } { <replaceable class="PARAMETER">value</replaceable> | '<replaceable class="PARAMETER">value</replaceable>' | DEFAULT }
+
+ALTER SYSTEM RESET <replaceable class="PARAMETER">configuration_parameter</replaceable>
+ALTER SYSTEM RESET ALL
 </synopsis>
  </refsynopsisdiv>
 
@@ -30,10 +33,12 @@ ALTER SYSTEM SET <replaceable class="PARAMETER">configuration_parameter</replace
 
   <para>
    <command>ALTER SYSTEM</command> writes the configuration parameter
-   values to the <filename>postgresql.auto.conf</filename> file. With
-   <literal>DEFAULT</literal>, it removes a configuration entry from
-   <filename>postgresql.auto.conf</filename> file. The values will be
-   effective after reload of server configuration (SIGHUP) or in next
+   values to the <filename>postgresql.auto.conf</filename> file.
+   Setting the parameter to <literal>DEFAULT</literal>, or using the
+   <command>RESET</command> variant, removes the configuration entry from
+   <filename>postgresql.auto.conf</filename> file. Use <literal>RESET
+   ALL</literal> to clear all configuration entries.  The values will
+   be effective after reload of server configuration (SIGHUP) or in next
    server start based on the type of configuration parameter modified.
   </para>
 

diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 6f4d6455df69d2e31ea3c76c1bb38c577eb77e0d..b46dd7b008caf407aa29606ee3e2cd094e3f4d4f 100644 (file)
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -411,7 +411,8 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 
 %type <istmt>  insert_rest
 
-%type <vsetstmt> generic_set set_rest set_rest_more SetResetClause FunctionSetResetClause
+%type <vsetstmt> generic_set set_rest set_rest_more generic_reset reset_rest
+                SetResetClause FunctionSetResetClause
 
 %type <node>   TableElement TypedTableElement ConstraintElem TableFuncElement
 %type <node>   columnDef columnOptions
@@ -1579,39 +1580,47 @@ NonReservedWord_or_Sconst:
        ;
 
 VariableResetStmt:
-           RESET var_name
+           RESET reset_rest                        { $$ = (Node *) $2; }
+       ;
+
+reset_rest:
+           generic_reset                           { $$ = $1; }
+           | TIME ZONE
                {
                    VariableSetStmt *n = makeNode(VariableSetStmt);
                    n->kind = VAR_RESET;
-                   n->name = $2;
-                   $$ = (Node *) n;
+                   n->name = "timezone";
+                   $$ = n;
                }
-           | RESET TIME ZONE
+           | TRANSACTION ISOLATION LEVEL
                {
                    VariableSetStmt *n = makeNode(VariableSetStmt);
                    n->kind = VAR_RESET;
-                   n->name = "timezone";
-                   $$ = (Node *) n;
+                   n->name = "transaction_isolation";
+                   $$ = n;
                }
-           | RESET TRANSACTION ISOLATION LEVEL
+           | SESSION AUTHORIZATION
                {
                    VariableSetStmt *n = makeNode(VariableSetStmt);
                    n->kind = VAR_RESET;
-                   n->name = "transaction_isolation";
-                   $$ = (Node *) n;
+                   n->name = "session_authorization";
+                   $$ = n;
                }
-           | RESET SESSION AUTHORIZATION
+       ;
+
+generic_reset:
+           var_name
                {
                    VariableSetStmt *n = makeNode(VariableSetStmt);
                    n->kind = VAR_RESET;
-                   n->name = "session_authorization";
-                   $$ = (Node *) n;
+                   n->name = $1;
+                   $$ = n;
                }
-           | RESET ALL
+           | ALL
                {
                    VariableSetStmt *n = makeNode(VariableSetStmt);
                    n->kind = VAR_RESET_ALL;
-                   $$ = (Node *) n;
+                   $$ = n;
                }
        ;
 
@@ -8494,7 +8503,7 @@ DropdbStmt: DROP DATABASE database_name
 
 /*****************************************************************************
  *
- *     ALTER SYSTEM SET
+ *     ALTER SYSTEM
  *
  * This is used to change configuration parameters persistently.
  *****************************************************************************/
@@ -8506,6 +8515,12 @@ AlterSystemStmt:
                    n->setstmt = $4;
                    $$ = (Node *)n;
                }
+           | ALTER SYSTEM_P RESET generic_reset
+               {
+                   AlterSystemStmt *n = makeNode(AlterSystemStmt);
+                   n->setstmt = $4;
+                   $$ = (Node *)n;
+               }
        ;
 
 

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 8c57803afe2694bdc0bfe0913c9a0d6fe9a4b4c0..af667f54ada520db97d45b8929458dba0c6c96d2 100644 (file)
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -6696,6 +6696,8 @@ replace_auto_config_value(ConfigVariable **head_p, ConfigVariable **tail_p,
  * This function takes all previous configuration parameters
  * set by ALTER SYSTEM command and the currently set ones
  * and write them all to the automatic configuration file.
+ * It just writes an empty file incase user wants to reset
+ * all the parameters.
  *
  * The configuration parameters are written to a temporary
  * file then renamed to the final name.
@@ -6710,6 +6712,7 @@ AlterSystemSetConfigFile(AlterSystemStmt *altersysstmt)
 {
    char       *name;
    char       *value;
+   bool        resetall = false;
    int         Tmpfd = -1;
    FILE       *infile;
    struct config_generic *record;
@@ -6737,37 +6740,48 @@ AlterSystemSetConfigFile(AlterSystemStmt *altersysstmt)
            break;
 
        case VAR_SET_DEFAULT:
+       case VAR_RESET:
+           value = NULL;
+           break;
+
+       case VAR_RESET_ALL:
            value = NULL;
+           resetall = true;
            break;
+
        default:
            elog(ERROR, "unrecognized alter system stmt type: %d",
                 altersysstmt->setstmt->kind);
            break;
    }
 
-   record = find_option(name, false, LOG);
-   if (record == NULL)
-       ereport(ERROR,
-               (errcode(ERRCODE_UNDEFINED_OBJECT),
-              errmsg("unrecognized configuration parameter \"%s\"", name)));
+   /* If we're resetting everything, there's no need to validate anything */
+   if (!resetall)
+   {
+       record = find_option(name, false, LOG);
+       if (record == NULL)
+           ereport(ERROR,
+                   (errcode(ERRCODE_UNDEFINED_OBJECT),
+                  errmsg("unrecognized configuration parameter \"%s\"", name)));
 
-   /*
-    * Don't allow the parameters which can't be set in configuration
-    * files to be set in PG_AUTOCONF_FILENAME file.
-    */
-   if ((record->context == PGC_INTERNAL) ||
-       (record->flags & GUC_DISALLOW_IN_FILE) ||
-       (record->flags & GUC_DISALLOW_IN_AUTO_FILE))
-        ereport(ERROR,
-                (errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
-                 errmsg("parameter \"%s\" cannot be changed",
-                        name)));
-
-   if (!validate_conf_option(record, name, value, PGC_S_FILE,
-                             ERROR, true, NULL,
-                             &newextra))
-       ereport(ERROR,
-       (errmsg("invalid value for parameter \"%s\": \"%s\"", name, value)));
+       /*
+        * Don't allow the parameters which can't be set in configuration
+        * files to be set in PG_AUTOCONF_FILENAME file.
+        */
+       if ((record->context == PGC_INTERNAL) ||
+           (record->flags & GUC_DISALLOW_IN_FILE) ||
+           (record->flags & GUC_DISALLOW_IN_AUTO_FILE))
+            ereport(ERROR,
+                    (errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
+                     errmsg("parameter \"%s\" cannot be changed",
+                            name)));
+
+       if (!validate_conf_option(record, name, value, PGC_S_FILE,
+                                 ERROR, true, NULL,
+                                 &newextra))
+           ereport(ERROR,
+           (errmsg("invalid value for parameter \"%s\": \"%s\"", name, value)));
+   }
 
 
    /*
@@ -6799,26 +6813,34 @@ AlterSystemSetConfigFile(AlterSystemStmt *altersysstmt)
 
    PG_TRY();
    {
-       if (stat(AutoConfFileName, &st) == 0)
+       /*
+        * If we're going to reset everything, then don't open the file, don't
+        * parse it, and don't do anything with the configuration list.  Just
+        * write out an empty file.
+        */
+       if (!resetall)
        {
-           /* open file PG_AUTOCONF_FILENAME */
-           infile = AllocateFile(AutoConfFileName, "r");
-           if (infile == NULL)
-               ereport(ERROR,
-                       (errmsg("failed to open auto conf file \"%s\": %m ",
-                               AutoConfFileName)));
+           if (stat(AutoConfFileName, &st) == 0)
+           {
+               /* open file PG_AUTOCONF_FILENAME */
+               infile = AllocateFile(AutoConfFileName, "r");
+               if (infile == NULL)
+                   ereport(ERROR,
+                           (errmsg("failed to open auto conf file \"%s\": %m ",
+                                   AutoConfFileName)));
 
-           /* parse it */
-           ParseConfigFp(infile, AutoConfFileName, 0, LOG, &head, &tail);
+               /* parse it */
+               ParseConfigFp(infile, AutoConfFileName, 0, LOG, &head, &tail);
 
-           FreeFile(infile);
-       }
+               FreeFile(infile);
+           }
 
-       /*
-        * replace with new value if the configuration parameter already
-        * exists OR add it as a new cofiguration parameter in the file.
-        */
-       replace_auto_config_value(&head, &tail, AutoConfFileName, name, value);
+           /*
+            * replace with new value if the configuration parameter already
+            * exists OR add it as a new cofiguration parameter in the file.
+            */
+           replace_auto_config_value(&head, &tail, AutoConfFileName, name, value);
+       }
 
        /* Write and sync the new contents to the temporary file */
        write_auto_conf_file(Tmpfd, AutoConfTmpFileName, &head);

diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 76b2b04c1acd3186657a93a039a9c41b9cefe36e..8288b41f0a5ebbebe6c33b288fcf77bd9043d90e 100644 (file)
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -545,7 +545,8 @@ static const SchemaQuery Query_for_list_of_matviews = {
 "SELECT name FROM "\
 " (SELECT pg_catalog.lower(name) AS name FROM pg_catalog.pg_settings "\
 "  WHERE context != 'internal') ss "\
-" WHERE substring(name,1,%d)='%s'"
+" WHERE substring(name,1,%d)='%s'"\
+" UNION ALL SELECT 'all' ss"
 
 #define Query_for_list_of_set_vars \
 "SELECT name FROM "\
@@ -963,7 +964,7 @@ psql_completion(const char *text, int start, int end)
        {"AGGREGATE", "COLLATION", "CONVERSION", "DATABASE", "DEFAULT PRIVILEGES", "DOMAIN",
            "EVENT TRIGGER", "EXTENSION", "FOREIGN DATA WRAPPER", "FOREIGN TABLE", "FUNCTION",
            "GROUP", "INDEX", "LANGUAGE", "LARGE OBJECT", "MATERIALIZED VIEW", "OPERATOR",
-           "ROLE", "RULE", "SCHEMA", "SERVER", "SEQUENCE", "SYSTEM SET", "TABLE",
+           "ROLE", "RULE", "SCHEMA", "SERVER", "SEQUENCE", "SYSTEM", "TABLE",
            "TABLESPACE", "TEXT SEARCH", "TRIGGER", "TYPE",
        "USER", "USER MAPPING FOR", "VIEW", NULL};
 
@@ -1328,10 +1329,20 @@ psql_completion(const char *text, int start, int end)
 
        COMPLETE_WITH_LIST(list_ALTER_SERVER);
    }
-   /* ALTER SYSTEM SET <name> */
+   /* ALTER SYSTEM SET, RESET, RESET ALL */
+   else if (pg_strcasecmp(prev2_wd, "ALTER") == 0 &&
+            pg_strcasecmp(prev_wd, "SYSTEM") == 0)
+   {
+       static const char *const list_ALTERSYSTEM[] =
+       {"SET", "RESET", NULL};
+
+       COMPLETE_WITH_LIST(list_ALTERSYSTEM);
+   }
+   /* ALTER SYSTEM SET|RESET <name> */
    else if (pg_strcasecmp(prev3_wd, "ALTER") == 0 &&
             pg_strcasecmp(prev2_wd, "SYSTEM") == 0 &&
-            pg_strcasecmp(prev_wd, "SET") == 0)
+            (pg_strcasecmp(prev_wd, "SET") == 0 ||
+            pg_strcasecmp(prev_wd, "RESET") == 0))
        COMPLETE_WITH_QUERY(Query_for_list_of_alter_system_set_vars);
    /* ALTER VIEW <name> */
    else if (pg_strcasecmp(prev3_wd, "ALTER") == 0 &&