Adding upstream version 14.5.upstream/14.5upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 588 insertions, 0 deletions

diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
new file mode 100644
index 0000000..f24464d
--- /dev/null
+++ b/src/backend/commands/view.c
@@ -0,0 +1,588 @@
+/*-------------------------------------------------------------------------
+ *
+ * view.c
+ *	  use rewrite rules to construct views
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/commands/view.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/relation.h"
+#include "access/xact.h"
+#include "catalog/namespace.h"
+#include "commands/defrem.h"
+#include "commands/tablecmds.h"
+#include "commands/view.h"
+#include "miscadmin.h"
+#include "nodes/makefuncs.h"
+#include "nodes/nodeFuncs.h"
+#include "parser/analyze.h"
+#include "parser/parse_relation.h"
+#include "rewrite/rewriteDefine.h"
+#include "rewrite/rewriteHandler.h"
+#include "rewrite/rewriteManip.h"
+#include "rewrite/rewriteSupport.h"
+#include "utils/acl.h"
+#include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/rel.h"
+#include "utils/syscache.h"
+
+static void checkViewTupleDesc(TupleDesc newdesc, TupleDesc olddesc);
+
+/*---------------------------------------------------------------------
+ * DefineVirtualRelation
+ *
+ * Create a view relation and use the rules system to store the query
+ * for the view.
+ *
+ * EventTriggerAlterTableStart must have been called already.
+ *---------------------------------------------------------------------
+ */
+static ObjectAddress
+DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
+					  List *options, Query *viewParse)
+{
+	Oid			viewOid;
+	LOCKMODE	lockmode;
+	CreateStmt *createStmt = makeNode(CreateStmt);
+	List	   *attrList;
+	ListCell   *t;
+
+	/*
+	 * create a list of ColumnDef nodes based on the names and types of the
+	 * (non-junk) targetlist items from the view's SELECT list.
+	 */
+	attrList = NIL;
+	foreach(t, tlist)
+	{
+		TargetEntry *tle = (TargetEntry *) lfirst(t);
+
+		if (!tle->resjunk)
+		{
+			ColumnDef  *def = makeColumnDef(tle->resname,
+											exprType((Node *) tle->expr),
+											exprTypmod((Node *) tle->expr),
+											exprCollation((Node *) tle->expr));
+
+			/*
+			 * It's possible that the column is of a collatable type but the
+			 * collation could not be resolved, so double-check.
+			 */
+			if (type_is_collatable(exprType((Node *) tle->expr)))
+			{
+				if (!OidIsValid(def->collOid))
+					ereport(ERROR,
+							(errcode(ERRCODE_INDETERMINATE_COLLATION),
+							 errmsg("could not determine which collation to use for view column \"%s\"",
+									def->colname),
+							 errhint("Use the COLLATE clause to set the collation explicitly.")));
+			}
+			else
+				Assert(!OidIsValid(def->collOid));
+
+			attrList = lappend(attrList, def);
+		}
+	}
+
+	/*
+	 * Look up, check permissions on, and lock the creation namespace; also
+	 * check for a preexisting view with the same name.  This will also set
+	 * relation->relpersistence to RELPERSISTENCE_TEMP if the selected
+	 * namespace is temporary.
+	 */
+	lockmode = replace ? AccessExclusiveLock : NoLock;
+	(void) RangeVarGetAndCheckCreationNamespace(relation, lockmode, &viewOid);
+
+	if (OidIsValid(viewOid) && replace)
+	{
+		Relation	rel;
+		TupleDesc	descriptor;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		ObjectAddress address;
+
+		/* Relation is already locked, but we must build a relcache entry. */
+		rel = relation_open(viewOid, NoLock);
+
+		/* Make sure it *is* a view. */
+		if (rel->rd_rel->relkind != RELKIND_VIEW)
+			ereport(ERROR,
+					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					 errmsg("\"%s\" is not a view",
+							RelationGetRelationName(rel))));
+
+		/* Also check it's not in use already */
+		CheckTableNotInUse(rel, "CREATE OR REPLACE VIEW");
+
+		/*
+		 * Due to the namespace visibility rules for temporary objects, we
+		 * should only end up replacing a temporary view with another
+		 * temporary view, and similarly for permanent views.
+		 */
+		Assert(relation->relpersistence == rel->rd_rel->relpersistence);
+
+		/*
+		 * Create a tuple descriptor to compare against the existing view, and
+		 * verify that the old column list is an initial prefix of the new
+		 * column list.
+		 */
+		descriptor = BuildDescForRelation(attrList);
+		checkViewTupleDesc(descriptor, rel->rd_att);
+
+		/*
+		 * If new attributes have been added, we must add pg_attribute entries
+		 * for them.  It is convenient (although overkill) to use the ALTER
+		 * TABLE ADD COLUMN infrastructure for this.
+		 *
+		 * Note that we must do this before updating the query for the view,
+		 * since the rules system requires that the correct view columns be in
+		 * place when defining the new rules.
+		 *
+		 * Also note that ALTER TABLE doesn't run parse transformation on
+		 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready
+		 * to execute as-is.
+		 */
+		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);
+			}
+
+			/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+			AlterTableInternal(viewOid, atcmds, true);
+
+			/* Make the new view columns visible */
+			CommandCounterIncrement();
+		}
+
+		/*
+		 * Update the query for the view.
+		 *
+		 * Note that we must do this before updating the view options, because
+		 * the new options may not be compatible with the old view query (for
+		 * example if we attempt to add the WITH CHECK OPTION, we require that
+		 * the new view be automatically updatable, but the old view may not
+		 * have been).
+		 */
+		StoreViewQuery(viewOid, viewParse, replace);
+
+		/* Make the new view query visible */
+		CommandCounterIncrement();
+
+		/*
+		 * Update the view's options.
+		 *
+		 * The new options list replaces the existing options list, even if
+		 * it's empty.
+		 */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) options;
+		atcmds = list_make1(atcmd);
+
+		/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+		AlterTableInternal(viewOid, atcmds, true);
+
+		/*
+		 * There is very little to do here to update the view's dependencies.
+		 * Most view-level dependency relationships, such as those on the
+		 * owner, schema, and associated composite type, aren't changing.
+		 * Because we don't allow changing type or collation of an existing
+		 * view column, those dependencies of the existing columns don't
+		 * change either, while the AT_AddColumnToView machinery took care of
+		 * adding such dependencies for new view columns.  The dependencies of
+		 * the view's query could have changed arbitrarily, but that was dealt
+		 * with inside StoreViewQuery.  What remains is only to check that
+		 * view replacement is allowed when we're creating an extension.
+		 */
+		ObjectAddressSet(address, RelationRelationId, viewOid);
+
+		recordDependencyOnCurrentExtension(&address, true);
+
+		/*
+		 * Seems okay, so return the OID of the pre-existing view.
+		 */
+		relation_close(rel, NoLock);	/* keep the lock! */
+
+		return address;
+	}
+	else
+	{
+		ObjectAddress address;
+
+		/*
+		 * Set the parameters for keys/inheritance etc. All of these are
+		 * uninteresting for views...
+		 */
+		createStmt->relation = relation;
+		createStmt->tableElts = attrList;
+		createStmt->inhRelations = NIL;
+		createStmt->constraints = NIL;
+		createStmt->options = options;
+		createStmt->oncommit = ONCOMMIT_NOOP;
+		createStmt->tablespacename = NULL;
+		createStmt->if_not_exists = false;
+
+		/*
+		 * 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).
+		 */
+		address = DefineRelation(createStmt, RELKIND_VIEW, InvalidOid, NULL,
+								 NULL);
+		Assert(address.objectId != InvalidOid);
+
+		/* Make the new view relation visible */
+		CommandCounterIncrement();
+
+		/* Store the query for the view */
+		StoreViewQuery(address.objectId, viewParse, replace);
+
+		return address;
+	}
+}
+
+/*
+ * Verify that tupledesc associated with proposed new view definition
+ * matches tupledesc of old view.  This is basically a cut-down version
+ * of equalTupleDescs(), with code added to generate specific complaints.
+ * Also, we allow the new tupledesc to have more columns than the old.
+ */
+static void
+checkViewTupleDesc(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				 errmsg("cannot drop columns from view")));
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on view anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+							NameStr(oldattr->attname),
+							NameStr(newattr->attname)),
+					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		/* XXX would it be safe to allow atttypmod to change?  Not sure */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+							NameStr(oldattr->attname),
+							format_type_with_typemod(oldattr->atttypid,
+													 oldattr->atttypmod),
+							format_type_with_typemod(newattr->atttypid,
+													 newattr->atttypmod))));
+		/* We can ignore the remaining attributes of an attribute... */
+	}
+
+	/*
+	 * We ignore the constraint fields.  The new view desc can't have any
+	 * constraints, and the only ones that could be on the old view are
+	 * defaults, which we are happy to leave in place.
+	 */
+}
+
+static void
+DefineViewRules(Oid viewOid, Query *viewParse, bool replace)
+{
+	/*
+	 * Set up the ON SELECT rule.  Since the query has already been through
+	 * parse analysis, we use DefineQueryRewrite() directly.
+	 */
+	DefineQueryRewrite(pstrdup(ViewSelectRuleName),
+					   viewOid,
+					   NULL,
+					   CMD_SELECT,
+					   true,
+					   replace,
+					   list_make1(viewParse));
+
+	/*
+	 * Someday: automatic ON INSERT, etc
+	 */
+}
+
+/*---------------------------------------------------------------
+ * UpdateRangeTableOfViewParse
+ *
+ * Update the range table of the given parsetree.
+ * This update consists of adding two new entries IN THE BEGINNING
+ * of the range table (otherwise the rule system will die a slow,
+ * horrible and painful death, and we do not want that now, do we?)
+ * one for the OLD relation and one for the NEW one (both of
+ * them refer in fact to the "view" relation).
+ *
+ * Of course we must also increase the 'varnos' of all the Var nodes
+ * by 2...
+ *
+ * These extra RT entries are not actually used in the query,
+ * except for run-time locking and permission checking.
+ *---------------------------------------------------------------
+ */
+static Query *
+UpdateRangeTableOfViewParse(Oid viewOid, Query *viewParse)
+{
+	Relation	viewRel;
+	List	   *new_rt;
+	ParseNamespaceItem *nsitem;
+	RangeTblEntry *rt_entry1,
+			   *rt_entry2;
+	ParseState *pstate;
+
+	/*
+	 * Make a copy of the given parsetree.  It's not so much that we don't
+	 * want to scribble on our input, it's that the parser has a bad habit of
+	 * outputting multiple links to the same subtree for constructs like
+	 * BETWEEN, and we mustn't have OffsetVarNodes increment the varno of a
+	 * Var node twice.  copyObject will expand any multiply-referenced subtree
+	 * into multiple copies.
+	 */
+	viewParse = copyObject(viewParse);
+
+	/* Create a dummy ParseState for addRangeTableEntryForRelation */
+	pstate = make_parsestate(NULL);
+
+	/* need to open the rel for addRangeTableEntryForRelation */
+	viewRel = relation_open(viewOid, AccessShareLock);
+
+	/*
+	 * Create the 2 new range table entries and form the new range table...
+	 * OLD first, then NEW....
+	 */
+	nsitem = addRangeTableEntryForRelation(pstate, viewRel,
+										   AccessShareLock,
+										   makeAlias("old", NIL),
+										   false, false);
+	rt_entry1 = nsitem->p_rte;
+	nsitem = addRangeTableEntryForRelation(pstate, viewRel,
+										   AccessShareLock,
+										   makeAlias("new", NIL),
+										   false, false);
+	rt_entry2 = nsitem->p_rte;
+
+	/* Must override addRangeTableEntry's default access-check flags */
+	rt_entry1->requiredPerms = 0;
+	rt_entry2->requiredPerms = 0;
+
+	new_rt = lcons(rt_entry1, lcons(rt_entry2, viewParse->rtable));
+
+	viewParse->rtable = new_rt;
+
+	/*
+	 * Now offset all var nodes by 2, and jointree RT indexes too.
+	 */
+	OffsetVarNodes((Node *) viewParse, 2, 0);
+
+	relation_close(viewRel, AccessShareLock);
+
+	return viewParse;
+}
+
+/*
+ * DefineView
+ *		Execute a CREATE VIEW command.
+ */
+ObjectAddress
+DefineView(ViewStmt *stmt, const char *queryString,
+		   int stmt_location, int stmt_len)
+{
+	RawStmt    *rawstmt;
+	Query	   *viewParse;
+	RangeVar   *view;
+	ListCell   *cell;
+	bool		check_option;
+	ObjectAddress address;
+
+	/*
+	 * Run parse analysis to convert the raw parse tree to a Query.  Note this
+	 * also acquires sufficient locks on the source table(s).
+	 */
+	rawstmt = makeNode(RawStmt);
+	rawstmt->stmt = stmt->query;
+	rawstmt->stmt_location = stmt_location;
+	rawstmt->stmt_len = stmt_len;
+
+	viewParse = parse_analyze(rawstmt, queryString, NULL, 0, NULL);
+
+	/*
+	 * The grammar should ensure that the result is a single SELECT Query.
+	 * However, it doesn't forbid SELECT INTO, so we have to check for that.
+	 */
+	if (!IsA(viewParse, Query))
+		elog(ERROR, "unexpected parse analysis result");
+	if (viewParse->utilityStmt != NULL &&
+		IsA(viewParse->utilityStmt, CreateTableAsStmt))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("views must not contain SELECT INTO")));
+	if (viewParse->commandType != CMD_SELECT)
+		elog(ERROR, "unexpected parse analysis result");
+
+	/*
+	 * Check for unsupported cases.  These tests are redundant with ones in
+	 * DefineQueryRewrite(), but that function will complain about a bogus ON
+	 * SELECT rule, and we'd rather the message complain about a view.
+	 */
+	if (viewParse->hasModifyingCTE)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("views must not contain data-modifying statements in WITH")));
+
+	/*
+	 * If the user specified the WITH CHECK OPTION, add it to the list of
+	 * reloptions.
+	 */
+	if (stmt->withCheckOption == LOCAL_CHECK_OPTION)
+		stmt->options = lappend(stmt->options,
+								makeDefElem("check_option",
+											(Node *) makeString("local"), -1));
+	else if (stmt->withCheckOption == CASCADED_CHECK_OPTION)
+		stmt->options = lappend(stmt->options,
+								makeDefElem("check_option",
+											(Node *) makeString("cascaded"), -1));
+
+	/*
+	 * Check that the view is auto-updatable if WITH CHECK OPTION was
+	 * specified.
+	 */
+	check_option = false;
+
+	foreach(cell, stmt->options)
+	{
+		DefElem    *defel = (DefElem *) lfirst(cell);
+
+		if (strcmp(defel->defname, "check_option") == 0)
+			check_option = true;
+	}
+
+	/*
+	 * If the check option is specified, look to see if the view is actually
+	 * auto-updatable or not.
+	 */
+	if (check_option)
+	{
+		const char *view_updatable_error =
+		view_query_is_auto_updatable(viewParse, true);
+
+		if (view_updatable_error)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("WITH CHECK OPTION is supported only on automatically updatable views"),
+					 errhint("%s", _(view_updatable_error))));
+	}
+
+	/*
+	 * If a list of column names was given, run through and insert these into
+	 * the actual query tree. - thomas 2000-03-08
+	 */
+	if (stmt->aliases != NIL)
+	{
+		ListCell   *alist_item = list_head(stmt->aliases);
+		ListCell   *targetList;
+
+		foreach(targetList, viewParse->targetList)
+		{
+			TargetEntry *te = lfirst_node(TargetEntry, targetList);
+
+			/* junk columns don't get aliases */
+			if (te->resjunk)
+				continue;
+			te->resname = pstrdup(strVal(lfirst(alist_item)));
+			alist_item = lnext(stmt->aliases, alist_item);
+			if (alist_item == NULL)
+				break;			/* done assigning aliases */
+		}
+
+		if (alist_item != NULL)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("CREATE VIEW specifies more column "
+							"names than columns")));
+	}
+
+	/* Unlogged views are not sensible. */
+	if (stmt->view->relpersistence == RELPERSISTENCE_UNLOGGED)
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("views cannot be unlogged because they do not have storage")));
+
+	/*
+	 * If the user didn't explicitly ask for a temporary view, check whether
+	 * we need one implicitly.  We allow TEMP to be inserted automatically as
+	 * long as the CREATE command is consistent with that --- no explicit
+	 * schema name.
+	 */
+	view = copyObject(stmt->view);	/* don't corrupt original command */
+	if (view->relpersistence == RELPERSISTENCE_PERMANENT
+		&& isQueryUsingTempRelation(viewParse))
+	{
+		view->relpersistence = RELPERSISTENCE_TEMP;
+		ereport(NOTICE,
+				(errmsg("view \"%s\" will be a temporary view",
+						view->relname)));
+	}
+
+	/*
+	 * Create the view relation
+	 *
+	 * NOTE: if it already exists and replace is false, the xact will be
+	 * aborted.
+	 */
+	address = DefineVirtualRelation(view, viewParse->targetList,
+									stmt->replace, stmt->options, viewParse);
+
+	return address;
+}
+
+/*
+ * Use the rules system to store the query for the view.
+ */
+void
+StoreViewQuery(Oid viewOid, Query *viewParse, bool replace)
+{
+	/*
+	 * The range table of 'viewParse' does not contain entries for the "OLD"
+	 * and "NEW" relations. So... add them!
+	 */
+	viewParse = UpdateRangeTableOfViewParse(viewOid, viewParse);
+
+	/*
+	 * Now create the rules associated with the view.
+	 */
+	DefineViewRules(viewOid, viewParse, replace);
+}