Rework logic and simplify syntax of REINDEX DATABASE/SYSTEM

Per discussion, this commit includes a couple of changes to these two
flavors of REINDEX:
* The grammar is changed to make the name of the object optional, hence
one can rebuild all the indexes of the wanted area by specifying only
"REINDEX DATABASE;" or "REINDEX SYSTEM;".  Previously, the object name
was mandatory and had to match the name of the database on which the
command is issued.
* REINDEX DATABASE is changed to ignore catalogs, making this task only
possible with REINDEX SYSTEM.  This is a historical change, but there
was no way to work only on the indexes of a database without touching
the catalogs.  We have discussed more approaches here, like the addition
of an option to skip the catalogs without changing the original
behavior, but concluded that what we have here is for the best.

This builds on top of the TAP tests introduced in 5fb5b6c, showing the
change in behavior for REINDEX SYSTEM.  reindexdb is updated so as we do
not issue an extra REINDEX SYSTEM when working on a database in the
non-concurrent case, something that was confusing when --concurrently
got introduced, so this simplifies the code.

Author: Simon Riggs
Reviewed-by: Ashutosh Bapat, Bernd Helmle, Álvaro Herrera, Cary Huang,
Michael Paquier
Discussion: https://postgr.es/m/CANbhV-H=NH6Om4-X6cRjDWfH_Mu1usqwkuYVp-hwdB_PSHWRfg@mail.gmail.com

Author: michaelpq

doc/src/sgml/ref/reindex.sgml

@@ -21,7 +21,8 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-REINDEX [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] { INDEX | TABLE | SCHEMA | DATABASE | SYSTEM } [ CONCURRENTLY ] <replaceable class="parameter">name</replaceable>
+REINDEX [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] { INDEX | TABLE | SCHEMA } [ CONCURRENTLY ] <replaceable class="parameter">name</replaceable>
+REINDEX [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] { DATABASE | SYSTEM } [ CONCURRENTLY ] [ <replaceable class="parameter">name</replaceable> ]
 
 <phrase>where <replaceable class="parameter">option</replaceable> can be one of:</phrase>
 
@@ -126,8 +127,9 @@ REINDEX [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] { IN
     <term><literal>DATABASE</literal></term>
     <listitem>
      <para>
-      Recreate all indexes within the current database.
-      Indexes on shared system catalogs are also processed.
+      Recreate all indexes within the current database, except system
+      catalogs.
+      Indexes on shared system catalogs are not processed.
       This form of <command>REINDEX</command> cannot be executed inside a
       transaction block.
      </para>
@@ -154,8 +156,8 @@ REINDEX [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] { IN
       The name of the specific index, table, or database to be
       reindexed.  Index and table names can be schema-qualified.
       Presently, <command>REINDEX DATABASE</command> and <command>REINDEX SYSTEM</command>
-      can only reindex the current database, so their parameter must match
-      the current database's name.
+      can only reindex the current database. Their parameter is optional,
+      and it must match the current database's name.
      </para>
     </listitem>
    </varlistentry>

src/backend/commands/indexcmds.c

@@ -2877,11 +2877,16 @@ ReindexMultipleTables(const char *objectName, ReindexObjectType objectKind,
 	bool		concurrent_warning = false;
 	bool		tablespace_warning = false;
 
-	AssertArg(objectName);
 	Assert(objectKind == REINDEX_OBJECT_SCHEMA ||
 		   objectKind == REINDEX_OBJECT_SYSTEM ||
 		   objectKind == REINDEX_OBJECT_DATABASE);
 
+	/*
+	 * This matches the options enforced by the grammar, where the object name
+	 * is optional for DATABASE and SYSTEM.
+	 */
+	AssertArg(objectName || objectKind != REINDEX_OBJECT_SCHEMA);
+
 	if (objectKind == REINDEX_OBJECT_SYSTEM &&
 		(params->options & REINDEXOPT_CONCURRENTLY) != 0)
 		ereport(ERROR,
@@ -2906,13 +2911,13 @@ ReindexMultipleTables(const char *objectName, ReindexObjectType objectKind,
 	{
 		objectOid = MyDatabaseId;
 
-		if (strcmp(objectName, get_database_name(objectOid)) != 0)
+		if (objectName && strcmp(objectName, get_database_name(objectOid)) != 0)
 			ereport(ERROR,
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("can only reindex the currently open database")));
 		if (!pg_database_ownercheck(objectOid, GetUserId()))
 			aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_DATABASE,
-						   objectName);
+						   get_database_name(objectOid));
 	}
 
 	/*
@@ -2970,9 +2975,15 @@ ReindexMultipleTables(const char *objectName, ReindexObjectType objectKind,
 			!isTempNamespace(classtuple->relnamespace))
 			continue;
 
-		/* Check user/system classification, and optionally skip */
+		/*
+		 * Check user/system classification.  SYSTEM processes all the
+		 * catalogs, and DATABASE processes everything that's not a catalog.
+		 */
 		if (objectKind == REINDEX_OBJECT_SYSTEM &&
-			!IsSystemClass(relid, classtuple))
+			!IsCatalogRelationOid(relid))
+			continue;
+		else if (objectKind == REINDEX_OBJECT_DATABASE &&
+				 IsCatalogRelationOid(relid))
 			continue;
 
 		/*

src/backend/parser/gram.y

@@ -560,7 +560,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 %type <defelt>	generic_option_elem alter_generic_option_elem
 %type <list>	generic_option_list alter_generic_option_list
 
-%type <ival>	reindex_target_type reindex_target_multitable
+%type <ival>	reindex_target_type reindex_target_multitable reindex_name_optional
 
 %type <node>	copy_generic_opt_arg copy_generic_opt_arg_list_item
 %type <defelt>	copy_generic_opt_elem
@@ -9115,6 +9115,24 @@ ReindexStmt:
 											makeDefElem("concurrently", NULL, @3));
 					$$ = (Node *) n;
 				}
+			| REINDEX reindex_name_optional
+				{
+					ReindexStmt *n = makeNode(ReindexStmt);
+					n->kind = $2;
+					n->name = NULL;
+					n->relation = NULL;
+					n->params = NIL;
+					$$ = (Node *)n;
+				}
+			| REINDEX '(' utility_option_list ')' reindex_name_optional
+				{
+					ReindexStmt *n = makeNode(ReindexStmt);
+					n->kind = $5;
+					n->name = NULL;
+					n->relation = NULL;
+					n->params = $3;
+					$$ = (Node *)n;
+				}
 			| REINDEX '(' utility_option_list ')' reindex_target_type opt_concurrently qualified_name
 				{
 					ReindexStmt *n = makeNode(ReindexStmt);
@@ -9151,6 +9169,11 @@ reindex_target_multitable:
 			| SYSTEM_P				{ $$ = REINDEX_OBJECT_SYSTEM; }
 			| DATABASE				{ $$ = REINDEX_OBJECT_DATABASE; }
 		;
+/* For these options the name is optional */
+reindex_name_optional:
+			SYSTEM_P				{ $$ = REINDEX_OBJECT_SYSTEM; }
+			| DATABASE				{ $$ = REINDEX_OBJECT_DATABASE; }
+		;
 
 /*****************************************************************************
  *

src/bin/scripts/reindexdb.c

@@ -360,18 +360,6 @@ reindex_one_database(ConnParams *cparams, ReindexType type,
 		{
 			case REINDEX_DATABASE:
 
-				/*
-				 * Database-wide parallel reindex requires special processing.
-				 * If multiple jobs were asked, we have to reindex system
-				 * catalogs first as they cannot be processed in parallel.
-				 */
-				if (concurrently)
-					pg_log_warning("cannot reindex system catalogs concurrently, skipping all");
-				else
-					run_reindex_command(conn, REINDEX_SYSTEM, PQdb(conn), echo,
-										verbose, concurrently, false,
-										tablespace);
-
 				/* Build a list of relations from the database */
 				process_list = get_parallel_object_list(conn, process_type,
 														user_list, echo);

src/bin/scripts/t/090_reindexdb.pl

@@ -83,8 +83,8 @@
 	'SQL REINDEX run');
 my $relnode_info = $node->safe_psql('postgres', $compare_relfilenodes);
 is( $relnode_info,
-	qq(pg_constraint|pg_constraint_oid_index|relfilenode has changed
-pg_constraint|pg_toast.pg_toast_<oid>_index|relfilenode has changed
+	qq(pg_constraint|pg_constraint_oid_index|relfilenode is unchanged
+pg_constraint|pg_toast.pg_toast_<oid>_index|relfilenode is unchanged
 test1|pg_toast.pg_toast_<oid>_index|relfilenode has changed
 test1|test1x|relfilenode has changed),
 	'relfilenode change after REINDEX DATABASE');
@@ -235,11 +235,6 @@
 $node->command_fails(
 	[ 'reindexdb', '-j', '2', '-i', 'i1', 'postgres' ],
 	'parallel reindexdb cannot process indexes');
-$node->issues_sql_like(
-	[ 'reindexdb', '-j', '2', 'postgres' ],
-	qr/statement:\ REINDEX SYSTEM postgres;
-.*statement:\ REINDEX TABLE public\.test1/s,
-	'parallel reindexdb for database issues REINDEX SYSTEM first');
 # Note that the ordering of the commands is not stable, so the second
 # command for s2.t2 is not checked after.
 $node->issues_sql_like(
@@ -249,13 +244,8 @@
 $node->command_ok(
 	[ 'reindexdb', '-j', '2', '-S', 's3' ],
 	'parallel reindexdb with empty schema');
-$node->command_checks_all(
+$node->command_ok(
 	[ 'reindexdb', '-j', '2', '--concurrently', '-d', 'postgres' ],
-	0,
-	[qr/^$/],
-	[
-		qr/^reindexdb: warning: cannot reindex system catalogs concurrently, skipping all/s
-	],
-	'parallel reindexdb for system with --concurrently skips catalogs');
+	'parallel reindexdb on database, concurrently');
 
 done_testing();