* view.c
* use rewrite rules to construct views
*
- * Copyright (c) 1994, Regents of the University of California
+ * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
*
- * $Id: view.c,v 1.35 1999/07/15 23:03:08 momjian Exp $
+ *
+ * IDENTIFICATION
+ * $PostgreSQL: pgsql/src/backend/commands/view.c,v 1.81 2004/01/14 23:01:54 tgl Exp $
*
*-------------------------------------------------------------------------
*/
-#include <stdio.h>
-#include <string.h>
-
#include "postgres.h"
-#include "catalog/heap.h"
-#include "access/xact.h"
+#include "access/heapam.h"
+#include "catalog/dependency.h"
+#include "catalog/namespace.h"
+#include "commands/tablecmds.h"
+#include "commands/view.h"
+#include "miscadmin.h"
+#include "nodes/makefuncs.h"
#include "parser/parse_relation.h"
-#include "parser/parse_type.h"
#include "rewrite/rewriteDefine.h"
#include "rewrite/rewriteManip.h"
-#include "rewrite/rewriteRemove.h"
-#include "commands/creatinh.h"
-#include "commands/view.h"
+#include "rewrite/rewriteSupport.h"
+#include "utils/acl.h"
+#include "utils/lsyscache.h"
+
+
+static void checkViewTupleDesc(TupleDesc newdesc, TupleDesc olddesc);
+
/*---------------------------------------------------------------------
* DefineVirtualRelation
*
- * Create the "view" relation.
- * `DefineRelation' does all the work, we just provide the correct
- * arguments!
- *
- * 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)
{
- CreateStmt createStmt;
+ Oid viewOid,
+ namespaceId;
+ CreateStmt *createStmt = makeNode(CreateStmt);
List *attrList,
*t;
- TargetEntry *entry;
- Resdom *res;
- char *resname;
- char *restypename;
/*
- * 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 *entry = lfirst(t);
+ Resdom *res = entry->resdom;
+
+ if (!res->resjunk)
{
ColumnDef *def = makeNode(ColumnDef);
- TypeName *typename;
-
- /*
- * find the names of the attribute & its type
- */
- entry = lfirst(t);
- res = entry->resdom;
- resname = res->resname;
- restypename = typeidTypeName(res->restype);
+ TypeName *typename = makeNode(TypeName);
- typename = makeNode(TypeName);
+ def->colname = pstrdup(res->resname);
- typename->name = pstrdup(restypename);
+ typename->typeid = res->restype;
typename->typmod = res->restypmod;
-
- def->colname = pstrdup(resname);
-
def->typename = typename;
+ def->inhcount = 0;
+ def->is_local = true;
def->is_not_null = false;
- def->defval = (char *) NULL;
+ def->raw_default = NULL;
+ def->cooked_default = NULL;
+ def->constraints = NIL;
+ def->support = NULL;
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);
+ namespaceId = RangeVarGetCreationNamespace(relation);
+ viewOid = get_relname_relid(relation->relname, namespaceId);
+
+ 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));
+
+ /*
+ * Create a tuple descriptor to compare against the existing view,
+ * and verify it matches.
+ */
+ descriptor = BuildDescForRelation(attrList);
+ checkViewTupleDesc(descriptor, rel->rd_att);
+
+ /*
+ * Seems okay, so return the OID of the pre-existing view.
+ */
+ relation_close(rel, NoLock); /* keep the lock! */
+
+ return viewOid;
+ }
+ else
+ {
+ /*
+ * now create the parameters for keys/inheritance etc. All of them
+ * are nil...
+ */
+ createStmt->relation = (RangeVar *) relation;
+ createStmt->tableElts = attrList;
+ createStmt->inhRelations = NIL;
+ createStmt->constraints = NIL;
+ createStmt->hasoids = MUST_NOT_HAVE_OIDS;
+ createStmt->oncommit = ONCOMMIT_NOOP;
+
+ /*
+ * 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).
+ */
+ return DefineRelation(createStmt, RELKIND_VIEW);
+ }
}
-/*------------------------------------------------------------------
- * makeViewRetrieveRuleName
- *
- * Given a view name, returns the name for the 'on retrieve to "view"'
- * rule.
- * This routine is called when defining/removing a view.
- *------------------------------------------------------------------
+/*
+ * 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.
*/
-char *
-MakeRetrieveViewRuleName(char *viewName)
+static void
+checkViewTupleDesc(TupleDesc newdesc, TupleDesc olddesc)
{
- char *buf;
+ int i;
- buf = palloc(strlen(viewName) + 5);
- snprintf(buf, strlen(viewName) + 5, "_RET%s", viewName);
+ if (newdesc->natts != olddesc->natts)
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+ errmsg("cannot change number of columns in view")));
+ /* we can ignore tdhasoid */
+
+ for (i = 0; i < newdesc->natts; i++)
+ {
+ Form_pg_attribute newattr = newdesc->attrs[i];
+ Form_pg_attribute oldattr = olddesc->attrs[i];
+
+ /* XXX 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 change number of columns in 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\"",
+ NameStr(oldattr->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\"",
+ NameStr(oldattr->attname))));
+ /* We can ignore the remaining attributes of an attribute... */
+ }
- return buf;
+ /*
+ * 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 RuleStmt *
-FormViewRetrieveRule(char *viewName, Query *viewParse)
+FormViewRetrieveRule(const RangeVar *view, Query *viewParse, bool replace)
{
RuleStmt *rule;
- char *rname;
- Attr *attr;
/*
* Create a RuleStmt that corresponds to the suitable rewrite rule
* args for DefineQueryRewrite();
*/
rule = makeNode(RuleStmt);
- rname = MakeRetrieveViewRuleName(viewName);
-
- attr = makeNode(Attr);
- attr->relname = pstrdup(viewName);
-/* attr->refname = pstrdup(viewName);*/
- rule->rulename = pstrdup(rname);
+ rule->relation = copyObject((RangeVar *) view);
+ rule->rulename = pstrdup(ViewSelectRuleName);
rule->whereClause = NULL;
rule->event = CMD_SELECT;
- rule->object = attr;
rule->instead = true;
- rule->actions = lcons(viewParse, NIL);
+ rule->actions = makeList1(viewParse);
+ rule->replace = replace;
return rule;
}
static void
-DefineViewRules(char *viewName, Query *viewParse)
+DefineViewRules(const RangeVar *view, Query *viewParse, bool replace)
{
- RuleStmt *retrieve_rule = NULL;
+ RuleStmt *retrieve_rule;
#ifdef NOTYET
- RuleStmt *replace_rule = NULL;
- RuleStmt *append_rule = NULL;
- RuleStmt *delete_rule = NULL;
-
+ RuleStmt *replace_rule;
+ RuleStmt *append_rule;
+ RuleStmt *delete_rule;
#endif
- retrieve_rule = FormViewRetrieveRule(viewName, viewParse);
+ retrieve_rule = FormViewRetrieveRule(view, viewParse, replace);
#ifdef NOTYET
-
- replace_rule = FormViewReplaceRule(viewName, viewParse);
- append_rule = FormViewAppendRule(viewName, viewParse);
- delete_rule = FormViewDeleteRule(viewName, viewParse);
-
+ replace_rule = FormViewReplaceRule(view, viewParse);
+ append_rule = FormViewAppendRule(view, viewParse);
+ delete_rule = FormViewDeleteRule(view, viewParse);
#endif
DefineQueryRewrite(retrieve_rule);
* 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;
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);
/*
- * 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, viewOid,
+ makeAlias("*OLD*", NIL),
+ false, false);
+ rt_entry2 = addRangeTableEntryForRelation(NULL, viewOid,
+ 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);
+
+ return viewParse;
}
/*-------------------------------------------------------------------
*-------------------------------------------------------------------
*/
void
-DefineView(char *viewName, Query *viewParse)
+DefineView(const RangeVar *view, Query *viewParse, bool replace)
{
- List *viewTlist;
-
- viewTlist = viewParse->targetList;
+ Oid viewOid;
/*
- * Create the "view" relation NOTE: if it already exists, the xaxt
- * will be aborted.
+ * Create the view relation
+ *
+ * NOTE: if it already exists and replace is false, the xact will be
+ * aborted.
*/
- DefineVirtualRelation(viewName, viewTlist);
+
+ viewOid = DefineVirtualRelation(view, viewParse->targetList, replace);
/*
* The relation we have just created is not visible to any other
/*
* 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...
+ * "OLD" and "NEW" relations. So... add them!
*/
- UpdateRangeTableOfViewParse(viewName, viewParse);
- DefineViewRules(viewName, viewParse);
+ viewParse = UpdateRangeTableOfViewParse(viewOid, viewParse);
+
+ /*
+ * Now create the rules associated with the view.
+ */
+ DefineViewRules(view, viewParse, replace);
}
-/*------------------------------------------------------------------
+/*
* RemoveView
*
* Remove a view given its name
- *------------------------------------------------------------------
+ *
+ * We just have to drop the relation; the associated rules will be
+ * cleaned up automatically.
*/
void
-RemoveView(char *viewName)
+RemoveView(const RangeVar *view, DropBehavior behavior)
{
- char *rname;
+ Oid viewOid;
+ ObjectAddress object;
- /*
- * first remove all the "view" rules... Currently we only have one!
- */
- rname = MakeRetrieveViewRuleName(viewName);
- RemoveRewriteRule(rname);
+ viewOid = RangeVarGetRelid(view, false);
- /*
- * we don't really need that, but just in case...
- */
- CommandCounterIncrement();
+ object.classId = RelOid_pg_class;
+ object.objectId = viewOid;
+ object.objectSubId = 0;
- /*
- * now remove the relation.
- */
- heap_destroy_with_catalog(viewName);
- pfree(rname);
+ performDeletion(&object, behavior);
}
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