* view.c
* use rewrite rules to construct views
*
- * Copyright (c) 1994, Regents of the University of California
+ * Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
*
- * $Id: view.c,v 1.36 1999/07/16 04:58:42 momjian Exp $
+ *
+ * IDENTIFICATION
+ * src/backend/commands/view.c
*
*-------------------------------------------------------------------------
*/
-#include <stdio.h>
-#include <string.h>
-
#include "postgres.h"
+#include "access/heapam.h"
#include "access/xact.h"
-#include "catalog/heap.h"
-#include "commands/creatinh.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 "parser/parse_type.h"
#include "rewrite/rewriteDefine.h"
#include "rewrite/rewriteManip.h"
-#include "rewrite/rewriteRemove.h"
+#include "rewrite/rewriteSupport.h"
+#include "utils/acl.h"
+#include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/rel.h"
+
+
+static void checkViewTupleDesc(TupleDesc newdesc, TupleDesc olddesc);
+static bool isViewOnTempTable_walker(Node *node, void *context);
/*---------------------------------------------------------------------
- * DefineVirtualRelation
+ * isViewOnTempTable
*
- * Create the "view" relation.
- * `DefineRelation' does all the work, we just provide the correct
- * arguments!
+ * Returns true iff any of the relations underlying this view are
+ * temporary tables.
+ *---------------------------------------------------------------------
+ */
+static bool
+isViewOnTempTable(Query *viewParse)
+{
+ return isViewOnTempTable_walker((Node *) viewParse, NULL);
+}
+
+static bool
+isViewOnTempTable_walker(Node *node, void *context)
+{
+ if (node == NULL)
+ return false;
+
+ if (IsA(node, Query))
+ {
+ Query *query = (Query *) node;
+ ListCell *rtable;
+
+ foreach(rtable, query->rtable)
+ {
+ RangeTblEntry *rte = lfirst(rtable);
+
+ if (rte->rtekind == RTE_RELATION)
+ {
+ Relation rel = heap_open(rte->relid, AccessShareLock);
+ char relpersistence = rel->rd_rel->relpersistence;
+
+ heap_close(rel, AccessShareLock);
+ if (relpersistence == RELPERSISTENCE_TEMP)
+ return true;
+ }
+ }
+
+ return query_tree_walker(query,
+ isViewOnTempTable_walker,
+ context,
+ QTW_IGNORE_JOINALIASES);
+ }
+
+ return expression_tree_walker(node,
+ isViewOnTempTable_walker,
+ context);
+}
+
+/*---------------------------------------------------------------------
+ * DefineVirtualRelation
*
- * If the relation already exists, then 'DefineRelation' will abort
- * the xact...
+ * Create the "view" relation. `DefineRelation' does all the work,
+ * we just provide the correct arguments ... at least when we're
+ * creating a view. If we're updating an existing view, we have to
+ * work harder.
*---------------------------------------------------------------------
*/
-static void
-DefineVirtualRelation(char *relname, List *tlist)
+static Oid
+DefineVirtualRelation(const RangeVar *relation, List *tlist, bool replace,
+ Oid namespaceId)
{
- CreateStmt createStmt;
- List *attrList,
- *t;
- TargetEntry *entry;
- Resdom *res;
- char *resname;
- char *restypename;
+ Oid viewOid;
+ CreateStmt *createStmt = makeNode(CreateStmt);
+ List *attrList;
+ ListCell *t;
/*
- * create a list with one entry per attribute of this relation. Each
- * entry is a two element list. The first element is the name of the
- * attribute (a string) and the second the name of the type (NOTE: a
- * string, not a type id!).
+ * 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;
- if (tlist != NIL)
+ foreach(t, tlist)
{
- foreach(t, tlist)
+ TargetEntry *tle = lfirst(t);
+
+ if (!tle->resjunk)
{
ColumnDef *def = makeNode(ColumnDef);
- TypeName *typename;
+
+ def->colname = pstrdup(tle->resname);
+ def->typeName = makeTypeNameFromOid(exprType((Node *) tle->expr),
+ exprTypmod((Node *) tle->expr));
+ def->inhcount = 0;
+ def->is_local = true;
+ def->is_not_null = false;
+ def->is_from_type = false;
+ def->storage = 0;
+ def->raw_default = NULL;
+ def->cooked_default = NULL;
+ def->collClause = NULL;
+ def->collOid = exprCollation((Node *) tle->expr);
/*
- * find the names of the attribute & its type
+ * It's possible that the column is of a collatable type but the
+ * collation could not be resolved, so double-check.
*/
- entry = lfirst(t);
- res = entry->resdom;
- resname = res->resname;
- restypename = typeidTypeName(res->restype);
-
- typename = makeNode(TypeName);
-
- typename->name = pstrdup(restypename);
- typename->typmod = res->restypmod;
-
- def->colname = pstrdup(resname);
-
- def->typename = typename;
-
- def->is_not_null = false;
- def->defval = (char *) NULL;
+ 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));
+ def->constraints = NIL;
attrList = lappend(attrList, def);
}
}
- else
- elog(ERROR, "attempted to define virtual relation with no attrs");
- /*
- * now create the parametesr for keys/inheritance etc. All of them are
- * nil...
- */
- createStmt.relname = relname;
- createStmt.istemp = false;
- createStmt.tableElts = attrList;
-/* createStmt.tableType = NULL;*/
- createStmt.inhRelnames = NIL;
- createStmt.constraints = NIL;
+ if (attrList == NIL)
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+ errmsg("view must have at least one column")));
/*
- * finally create the relation...
+ * Check to see if we want to replace an existing view.
*/
- DefineRelation(&createStmt, RELKIND_RELATION);
-}
+ viewOid = get_relname_relid(relation->relname, namespaceId);
-/*------------------------------------------------------------------
- * makeViewRetrieveRuleName
- *
- * Given a view name, returns the name for the 'on retrieve to "view"'
- * rule.
- * This routine is called when defining/removing a view.
- *------------------------------------------------------------------
- */
-char *
-MakeRetrieveViewRuleName(char *viewName)
-{
- char *buf;
+ if (OidIsValid(viewOid) && replace)
+ {
+ Relation rel;
+ TupleDesc descriptor;
+
+ /*
+ * Yes. Get exclusive lock on the existing view ...
+ */
+ rel = relation_open(viewOid, AccessExclusiveLock);
+
+ /*
+ * Make sure it *is* a view, and do permissions checks.
+ */
+ if (rel->rd_rel->relkind != RELKIND_VIEW)
+ ereport(ERROR,
+ (errcode(ERRCODE_WRONG_OBJECT_TYPE),
+ errmsg("\"%s\" is not a view",
+ RelationGetRelationName(rel))));
+
+ if (!pg_class_ownercheck(viewOid, GetUserId()))
+ aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS,
+ 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.
+ */
+ if (list_length(attrList) > rel->rd_att->natts)
+ {
+ List *atcmds = NIL;
+ ListCell *c;
+ int skip = rel->rd_att->natts;
+
+ foreach(c, attrList)
+ {
+ AlterTableCmd *atcmd;
+
+ if (skip > 0)
+ {
+ skip--;
+ continue;
+ }
+ atcmd = makeNode(AlterTableCmd);
+ atcmd->subtype = AT_AddColumnToView;
+ atcmd->def = (Node *) lfirst(c);
+ atcmds = lappend(atcmds, atcmd);
+ }
+ AlterTableInternal(viewOid, atcmds, true);
+ }
- buf = palloc(strlen(viewName) + 5);
- snprintf(buf, strlen(viewName) + 5, "_RET%s", viewName);
+ /*
+ * Seems okay, so return the OID of the pre-existing view.
+ */
+ relation_close(rel, NoLock); /* keep the lock! */
- return buf;
+ return viewOid;
+ }
+ else
+ {
+ Oid relid;
+
+ /*
+ * now set the parameters for keys/inheritance etc. All of these are
+ * uninteresting for views...
+ */
+ createStmt->relation = (RangeVar *) relation;
+ createStmt->tableElts = attrList;
+ createStmt->inhRelations = NIL;
+ createStmt->constraints = NIL;
+ createStmt->options = list_make1(defWithOids(false));
+ createStmt->oncommit = ONCOMMIT_NOOP;
+ createStmt->tablespacename = NULL;
+ createStmt->if_not_exists = false;
+
+ /*
+ * finally 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).
+ */
+ relid = DefineRelation(createStmt, RELKIND_VIEW, InvalidOid);
+ Assert(relid != InvalidOid);
+ return relid;
+ }
}
-static RuleStmt *
-FormViewRetrieveRule(char *viewName, Query *viewParse)
+/*
+ * 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)
{
- RuleStmt *rule;
- char *rname;
- Attr *attr;
+ int i;
+
+ if (newdesc->natts < olddesc->natts)
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+ errmsg("cannot drop columns from view")));
+ /* we can ignore tdhasoid */
+
+ for (i = 0; i < olddesc->natts; i++)
+ {
+ Form_pg_attribute newattr = newdesc->attrs[i];
+ Form_pg_attribute oldattr = olddesc->attrs[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))));
+ /* 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... */
+ }
/*
- * Create a RuleStmt that corresponds to the suitable rewrite rule
- * args for DefineQueryRewrite();
+ * 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.
*/
- rule = makeNode(RuleStmt);
- rname = MakeRetrieveViewRuleName(viewName);
-
- attr = makeNode(Attr);
- attr->relname = pstrdup(viewName);
-/* attr->refname = pstrdup(viewName);*/
- rule->rulename = pstrdup(rname);
- rule->whereClause = NULL;
- rule->event = CMD_SELECT;
- rule->object = attr;
- rule->instead = true;
- rule->actions = lcons(viewParse, NIL);
-
- return rule;
}
static void
-DefineViewRules(char *viewName, Query *viewParse)
+DefineViewRules(Oid viewOid, Query *viewParse, bool replace)
{
- RuleStmt *retrieve_rule = NULL;
-
-#ifdef NOTYET
- RuleStmt *replace_rule = NULL;
- RuleStmt *append_rule = NULL;
- RuleStmt *delete_rule = NULL;
-
-#endif
-
- retrieve_rule = FormViewRetrieveRule(viewName, viewParse);
-
-#ifdef NOTYET
-
- replace_rule = FormViewReplaceRule(viewName, viewParse);
- append_rule = FormViewAppendRule(viewName, viewParse);
- delete_rule = FormViewDeleteRule(viewName, viewParse);
-
-#endif
-
- DefineQueryRewrite(retrieve_rule);
-
-#ifdef NOTYET
- DefineQueryRewrite(replace_rule);
- DefineQueryRewrite(append_rule);
- DefineQueryRewrite(delete_rule);
-#endif
+ /*
+ * 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
+ */
}
/*---------------------------------------------------------------
* 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 CURRENT relation and one for the NEW one (both of
+ * 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...
*
- * NOTE: these are destructive changes. It would be difficult to
- * make a complete copy of the parse tree and make the changes
- * in the copy.
+ * These extra RT entries are not actually used in the query,
+ * except for run-time permission checking.
*---------------------------------------------------------------
*/
-static void
-UpdateRangeTableOfViewParse(char *viewName, Query *viewParse)
+static Query *
+UpdateRangeTableOfViewParse(Oid viewOid, Query *viewParse)
{
- List *old_rt;
+ Relation viewRel;
List *new_rt;
RangeTblEntry *rt_entry1,
*rt_entry2;
/*
- * first offset all var nodes by 2
+ * 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.
*/
- OffsetVarNodes((Node *) viewParse->targetList, 2, 0);
- OffsetVarNodes(viewParse->qual, 2, 0);
-
- OffsetVarNodes(viewParse->havingQual, 2, 0);
+ viewParse = (Query *) copyObject(viewParse);
+ /* need to open the rel for addRangeTableEntryForRelation */
+ viewRel = relation_open(viewOid, AccessShareLock);
/*
- * find the old range table...
+ * Create the 2 new range table entries and form the new range table...
+ * OLD first, then NEW....
*/
- old_rt = viewParse->rtable;
+ rt_entry1 = addRangeTableEntryForRelation(NULL, viewRel,
+ makeAlias("old", NIL),
+ false, false);
+ rt_entry2 = addRangeTableEntryForRelation(NULL, viewRel,
+ makeAlias("new", NIL),
+ false, false);
+ /* 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));
- /*
- * create the 2 new range table entries and form the new range
- * table... CURRENT first, then NEW....
- */
- rt_entry1 = addRangeTableEntry(NULL, (char *) viewName, "*CURRENT*",
- FALSE, FALSE);
- rt_entry2 = addRangeTableEntry(NULL, (char *) viewName, "*NEW*",
- FALSE, FALSE);
- new_rt = lcons(rt_entry2, old_rt);
- new_rt = lcons(rt_entry1, new_rt);
+ viewParse->rtable = new_rt;
/*
- * Now the tricky part.... Update the range table in place... Be
- * careful here, or hell breaks loooooooooooooOOOOOOOOOOOOOOOOOOSE!
+ * Now offset all var nodes by 2, and jointree RT indexes too.
*/
- viewParse->rtable = new_rt;
+ OffsetVarNodes((Node *) viewParse, 2, 0);
+
+ relation_close(viewRel, AccessShareLock);
+
+ return viewParse;
}
-/*-------------------------------------------------------------------
+/*
* DefineView
- *
- * - takes a "viewname", "parsetree" pair and then
- * 1) construct the "virtual" relation
- * 2) commit the command but NOT the transaction,
- * so that the relation exists
- * before the rules are defined.
- * 2) define the "n" rules specified in the PRS2 paper
- * over the "virtual" relation
- *-------------------------------------------------------------------
+ * Execute a CREATE VIEW command.
*/
void
-DefineView(char *viewName, Query *viewParse)
+DefineView(ViewStmt *stmt, const char *queryString)
{
- List *viewTlist;
+ Query *viewParse;
+ Oid viewOid;
+ Oid namespaceId;
+ RangeVar *view;
- viewTlist = viewParse->targetList;
+ /*
+ * Run parse analysis to convert the raw parse tree to a Query. Note this
+ * also acquires sufficient locks on the source table(s).
+ *
+ * Since parse analysis scribbles on its input, copy the raw parse tree;
+ * this ensures we don't corrupt a prepared statement, for example.
+ */
+ viewParse = parse_analyze((Node *) copyObject(stmt->query),
+ queryString, NULL, 0);
/*
- * Create the "view" relation NOTE: if it already exists, the xaxt
- * will be aborted.
+ * The grammar should ensure that the result is a single SELECT Query.
*/
- DefineVirtualRelation(viewName, viewTlist);
+ if (!IsA(viewParse, Query) ||
+ viewParse->commandType != CMD_SELECT)
+ elog(ERROR, "unexpected parse analysis result");
/*
- * The relation we have just created is not visible to any other
- * commands running with the same transaction & command id. So,
- * increment the command id counter (but do NOT pfree any memory!!!!)
+ * 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.
*/
- CommandCounterIncrement();
+ if (viewParse->intoClause != NULL)
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("views must not contain SELECT INTO")));
+ if (viewParse->hasModifyingCTE)
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("views must not contain data-modifying statements in WITH")));
/*
- * The range table of 'viewParse' does not contain entries for the
- * "CURRENT" and "NEW" relations. So... add them! NOTE: we make the
- * update in place! After this call 'viewParse' will never be what it
- * used to be...
+ * If a list of column names was given, run through and insert these into
+ * the actual query tree. - thomas 2000-03-08
*/
- UpdateRangeTableOfViewParse(viewName, viewParse);
- DefineViewRules(viewName, viewParse);
-}
+ if (stmt->aliases != NIL)
+ {
+ ListCell *alist_item = list_head(stmt->aliases);
+ ListCell *targetList;
-/*------------------------------------------------------------------
- * RemoveView
- *
- * Remove a view given its name
- *------------------------------------------------------------------
- */
-void
-RemoveView(char *viewName)
-{
- char *rname;
+ foreach(targetList, viewParse->targetList)
+ {
+ TargetEntry *te = (TargetEntry *) lfirst(targetList);
+
+ Assert(IsA(te, TargetEntry));
+ /* junk columns don't get aliases */
+ if (te->resjunk)
+ continue;
+ te->resname = pstrdup(strVal(lfirst(alist_item)));
+ alist_item = lnext(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
+ && isViewOnTempTable(viewParse))
+ {
+ view->relpersistence = RELPERSISTENCE_TEMP;
+ ereport(NOTICE,
+ (errmsg("view \"%s\" will be a temporary view",
+ view->relname)));
+ }
+
+ /* Might also need to make it temporary if placed in temp schema. */
+ namespaceId = RangeVarGetCreationNamespace(view);
+ RangeVarAdjustRelationPersistence(view, namespaceId);
/*
- * first remove all the "view" rules... Currently we only have one!
+ * Create the view relation
+ *
+ * NOTE: if it already exists and replace is false, the xact will be
+ * aborted.
*/
- rname = MakeRetrieveViewRuleName(viewName);
- RemoveRewriteRule(rname);
+ viewOid = DefineVirtualRelation(view, viewParse->targetList,
+ stmt->replace, namespaceId);
/*
- * we don't really need that, but just in case...
+ * The relation we have just created is not visible to any other commands
+ * running with the same transaction & command id. So, increment the
+ * command id counter (but do NOT pfree any memory!!!!)
*/
CommandCounterIncrement();
/*
- * now remove the relation.
+ * 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.
*/
- heap_destroy_with_catalog(viewName);
- pfree(rname);
+ DefineViewRules(viewOid, viewParse, stmt->replace);
}
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