<!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/create_view.sgml,v 1.38 2008/12/06 23:22:46 momjian Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/create_view.sgml,v 1.39 2008/12/15 21:35:31 tgl Exp $
PostgreSQL documentation
-->
<para>
<command>CREATE OR REPLACE VIEW</command> is similar, but if a view
of the same name already exists, it is replaced. The new query must
- generate all of the same columns that were generated by the original query
- in the same order and with the same data types, but may add additional
- columns to the end of the list.
+ generate the same columns that were generated by the existing view query
+ (that is, the same column names in the same order and with the same data
+ types), but it may add additional columns to the end of the list. The
+ calculations giving rise to the output columns may be completely different.
</para>
<para>
</para>
</listitem>
</varlistentry>
-
+
<varlistentry>
<term><replaceable class="parameter">name</replaceable></term>
<listitem>
</programlisting>
</para>
</refsect1>
-
+
<refsect1>
<title>Compatibility</title>
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.273 2008/12/13 19:13:44 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.274 2008/12/15 21:35:31 tgl Exp $
*
*-------------------------------------------------------------------------
*/
attrdesc;
HeapTuple reltup;
FormData_pg_attribute attribute;
- int i;
- int minattnum,
- maxatts;
+ int newattnum;
char relkind;
HeapTuple typeTuple;
Oid typeOid;
0, 0, 0);
if (!HeapTupleIsValid(reltup))
elog(ERROR, "cache lookup failed for relation %u", myrelid);
+ relkind = ((Form_pg_class) GETSTRUCT(reltup))->relkind;
/*
* this test is deliberately not attisdropped-aware, since if one tries to
errmsg("column \"%s\" of relation \"%s\" already exists",
colDef->colname, RelationGetRelationName(rel))));
- minattnum = ((Form_pg_class) GETSTRUCT(reltup))->relnatts;
- relkind = ((Form_pg_class) GETSTRUCT(reltup))->relkind;
- maxatts = minattnum + 1;
- if (maxatts > MaxHeapAttributeNumber)
+ newattnum = ((Form_pg_class) GETSTRUCT(reltup))->relnatts + 1;
+ if (newattnum > MaxHeapAttributeNumber)
ereport(ERROR,
(errcode(ERRCODE_TOO_MANY_COLUMNS),
errmsg("tables can have at most %d columns",
MaxHeapAttributeNumber)));
- i = minattnum + 1;
typeTuple = typenameType(NULL, colDef->typename, &typmod);
tform = (Form_pg_type) GETSTRUCT(typeTuple);
/* make sure datatype is legal for a column */
CheckAttributeType(colDef->colname, typeOid);
+ /* construct new attribute's pg_attribute entry */
attribute.attrelid = myrelid;
namestrcpy(&(attribute.attname), colDef->colname);
attribute.atttypid = typeOid;
attribute.attlen = tform->typlen;
attribute.attcacheoff = -1;
attribute.atttypmod = typmod;
- attribute.attnum = i;
+ attribute.attnum = newattnum;
attribute.attbyval = tform->typbyval;
attribute.attndims = list_length(colDef->typename->arrayBounds);
attribute.attstorage = tform->typstorage;
/*
* Update number of attributes in pg_class tuple
*/
- ((Form_pg_class) GETSTRUCT(reltup))->relnatts = maxatts;
+ ((Form_pg_class) GETSTRUCT(reltup))->relnatts = newattnum;
simple_heap_update(pgclass, &reltup->t_self, reltup);
* returned by AddRelationNewConstraints, so that the right thing happens
* when a datatype's default applies.
*
- * We skip this logic completely for views.
+ * We skip this step completely for views. For a view, we can only get
+ * here from CREATE OR REPLACE VIEW, which historically doesn't set up
+ * defaults, not even for domain-typed columns. And in any case we mustn't
+ * invoke Phase 3 on a view, since it has no storage.
*/
- if (relkind != RELKIND_VIEW) {
+ if (relkind != RELKIND_VIEW)
+ {
defval = (Expr *) build_column_default(rel, attribute.attnum);
if (!defval && GetDomainConstraints(typeOid) != NIL)
/*
* Add needed dependency entries for the new column.
*/
- add_column_datatype_dependency(myrelid, i, attribute.atttypid);
+ add_column_datatype_dependency(myrelid, newattnum, attribute.atttypid);
}
/*
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/commands/view.c,v 1.108 2008/12/06 23:22:46 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/commands/view.c,v 1.109 2008/12/15 21:35:31 tgl Exp $
*
*-------------------------------------------------------------------------
*/
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
Assert(relation->istemp == rel->rd_istemp);
/*
- * If new attributes have been added, we must modify the pre-existing
- * view.
- */
- if (list_length(attrList) > rel->rd_att->natts) {
+ * 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) {
+ foreach(c, attrList)
+ {
AlterTableCmd *atcmd;
- if (skip > 0) {
- --skip;
+ if (skip > 0)
+ {
+ skip--;
continue;
}
atcmd = makeNode(AlterTableCmd);
atcmd->subtype = AT_AddColumnToView;
- atcmd->def = lfirst(c);
+ atcmd->def = (Node *) lfirst(c);
atcmds = lappend(atcmds, atcmd);
}
AlterTableInternal(viewOid, atcmds, true);
}
- /*
- * 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);
-
/*
* Seems okay, so return the OID of the pre-existing 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.
+ * Also, we allow the new tupledesc to have more columns than the old.
*/
static void
checkViewTupleDesc(TupleDesc newdesc, TupleDesc olddesc)
-- should fail
CREATE OR REPLACE VIEW viewtest AS
SELECT 1, * FROM viewtest_tbl;
-ERROR: column "b" of relation "viewtest" already exists
+ERROR: cannot change name of view column "a"
-- should fail
CREATE OR REPLACE VIEW viewtest AS
SELECT a, b::numeric FROM viewtest_tbl;
projects / thirdparty / postgresql.git / commitdiff
