[CF 5099] v6 - CREATE OR REPLACE MATERIALIZED VIEW

This branch was automatically generated by a robot using patches from an
email thread registered at:

https://commitfest.postgresql.org/patch/5099

The branch will be overwritten each time a new patch version is posted to
the thread, and also periodically to check for bitrot caused by changes
on the master branch.

Patch(es): https://www.postgresql.org/message-id/bf64dad9-eaaa-4911-b447-13acee89ea80@ewie.name
Author(s): Erik Wienhold

Author: Commitfest Bot

doc/src/sgml/ref/create_materialized_view.sgml

@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,14 +61,25 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
      <para>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
@@ -151,14 +163,23 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
       populated at creation time.  If not, the materialized view will be
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  For
+      newly created materialized views, this has the same effect as
+      <command>WITH DATA</command>.  Use this form if you want to use
+      <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command> as it requires
+      a populated materialized view.
+     </para>
     </listitem>
    </varlistentry>
 

src/backend/commands/createas.c

@@ -81,63 +81,159 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		/* Add new attributes via ALTER TABLE. */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/* Set access method via ALTER TABLE. */
+		if (into->accessMethod != NULL)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_SetAccessMethod;
+			atcmd->name = into->accessMethod;
+			atcmds = lappend(atcmds, atcmd);
+		}
+
+		/* Set tablespace via ALTER TABLE. */
+		if (into->tableSpaceName != NULL)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_SetTableSpace;
+			atcmd->name = into->tableSpaceName;
+			atcmds = lappend(atcmds, atcmd);
+		}
+
+		/* Set storage parameters via ALTER TABLE. */
+		if (into->options != NIL)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_ReplaceRelOptions;
+			atcmd->def = (Node *) into->options;
+			atcmds = lappend(atcmds, atcmd);
+		}
+
+		if (atcmds != NIL)
+		{
+			AlterTableInternal(matviewOid, atcmds, true);
+			CommandCounterIncrement();
+		}
+
+		relation_close(rel, NoLock);
+
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
+
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
+
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
 	{
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +330,34 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (!into->keepData)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -403,26 +526,28 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
 		 */
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 

src/backend/commands/tablecmds.c

@@ -4642,7 +4642,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4937,8 +4937,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5369,7 +5369,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);