*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/commands/Attic/command.c,v 1.171 2002/04/01 22:36:09 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/commands/Attic/command.c,v 1.172 2002/04/02 08:51:50 inoue Exp $
*
* NOTES
* The PerformAddAttribute() code, like most of the relation
}
-#ifdef _DROP_COLUMN_HACK__
-/*
- * ALTER TABLE DROP COLUMN trial implementation
- */
-
-/*
- * find a specified attribute in a node entry
- */
-static bool
-find_attribute_walker(Node *node, int *attnump)
-{
- if (node == NULL)
- return false;
- if (IsA(node, Var))
- {
- Var *var = (Var *) node;
-
- if (var->varlevelsup == 0 && var->varno == 1 &&
- var->varattno == *attnump)
- return true;
- }
- return expression_tree_walker(node, find_attribute_walker,
- (void *) attnump);
-}
-
-static bool
-find_attribute_in_node(Node *node, int attnum)
-{
- return find_attribute_walker(node, &attnum);
-}
-
-/*
- * Remove/check references for the column
- */
-static bool
-RemoveColumnReferences(Oid reloid, int attnum, bool checkonly, HeapTuple reltup)
-{
- Relation indexRelation,
- rcrel;
- ScanKeyData entry;
- HeapScanDesc scan;
- void *sysscan;
- HeapTuple htup,
- indexTuple;
- Form_pg_index index;
- Form_pg_class pgcform = (Form_pg_class) NULL;
- int i;
- bool checkok = true;
-
-
- if (!checkonly)
- pgcform = (Form_pg_class) GETSTRUCT(reltup);
-
- /*
- * Remove/check constraints here
- */
- ScanKeyEntryInitialize(&entry, (bits16) 0x0,
- Anum_pg_relcheck_rcrelid,
- (RegProcedure) F_OIDEQ,
- ObjectIdGetDatum(reloid));
-
- rcrel = heap_openr(RelCheckRelationName, RowExclusiveLock);
- sysscan = systable_beginscan(rcrel, RelCheckIndex, true,
- SnapshotNow,
- 1, &entry);
-
- while (HeapTupleIsValid(htup = systable_getnext(sysscan)))
- {
- Form_pg_relcheck relcheck;
- char *ccbin;
- Node *node;
-
- relcheck = (Form_pg_relcheck) GETSTRUCT(htup);
- ccbin = DatumGetCString(DirectFunctionCall1(textout,
- PointerGetDatum(&relcheck->rcbin)));
- node = stringToNode(ccbin);
- pfree(ccbin);
- if (find_attribute_in_node(node, attnum))
- {
- if (checkonly)
- {
- checkok = false;
- elog(ERROR, "target column is used in a constraint");
- }
- else
- {
- simple_heap_delete(rcrel, &htup->t_self);
- pgcform->relchecks--;
- }
- }
- }
-
- systable_endscan(sysscan);
- heap_close(rcrel, NoLock);
-
- /*
- * What to do with triggers/rules/views/procedues ?
- */
-
- /*
- * Remove/check indexes
- */
- indexRelation = heap_openr(IndexRelationName, RowExclusiveLock);
- ScanKeyEntryInitialize(&entry, 0, Anum_pg_index_indrelid, F_OIDEQ,
- ObjectIdGetDatum(reloid));
- scan = heap_beginscan(indexRelation, false, SnapshotNow, 1, &entry);
- while (HeapTupleIsValid(indexTuple = heap_getnext(scan, 0)))
- {
- index = (Form_pg_index) GETSTRUCT(indexTuple);
- for (i = 0; i < INDEX_MAX_KEYS; i++)
- {
- if (index->indkey[i] == InvalidAttrNumber)
- break;
- else if (index->indkey[i] == attnum)
- {
- if (checkonly)
- {
- checkok = false;
- elog(ERROR, "target column is used in an index");
- }
- else
- {
- index_drop(index->indexrelid);
- }
- break;
- }
- }
- }
- heap_endscan(scan);
- heap_close(indexRelation, NoLock);
-
- return checkok;
-}
-#endif /* _DROP_COLUMN_HACK__ */
/*
* ALTER TABLE DROP COLUMN
bool inh, const char *colName,
int behavior)
{
-#ifdef _DROP_COLUMN_HACK__
- Relation rel,
- attrdesc;
- HeapTuple reltup;
- HeapTupleData classtuple;
- Buffer buffer;
- Form_pg_attribute attribute;
- HeapTuple tup;
- Relation idescs[Num_pg_attr_indices];
- int attnum;
- bool hasindex;
- char dropColname[32];
-
- if (inh)
- elog(ERROR, "ALTER TABLE / DROP COLUMN with inherit option is not supported yet");
-
- /*
- * Grab an exclusive lock on the target table, which we will NOT
- * release until end of transaction.
- */
- rel = heap_open(myrelid, AccessExclusiveLock);
-
- if (rel->rd_rel->relkind != RELKIND_RELATION)
- elog(ERROR, "ALTER TABLE: relation \"%s\" is not a table",
- RelationGetRelationName(rel));
-
- if (!allowSystemTableMods
- && IsSystemRelationName(RelationGetRelationName(rel)))
- elog(ERROR, "ALTER TABLE: relation \"%s\" is a system catalog",
- RelationGetRelationName(rel));
-
- /*
- * permissions checking. this would normally be done in utility.c,
- * but this particular routine is recursive.
- *
- * normally, only the owner of a class can change its schema.
- */
- if (!pg_class_ownercheck(myrelid, GetUserId()))
- elog(ERROR, "ALTER TABLE: \"%s\": permission denied",
- RelationGetRelationName(rel));
-
- heap_close(rel, NoLock); /* close rel but keep lock! */
-
- /*
- * What to do when rel has inheritors ?
- */
- if (length(find_all_inheritors(myrelid)) > 1)
- elog(ERROR, "ALTER TABLE: cannot drop a column on table that is inherited from");
-
- /*
- * lock the pg_class tuple for update
- */
- rel = heap_openr(RelationRelationName, RowExclusiveLock);
- reltup = SearchSysCache(RELOID,
- ObjectIdGetDatum(myrelid),
- 0, 0, 0);
- if (!HeapTupleIsValid(reltup))
- {
- Relation myrel;
- char *myrelname;
-
- myrel = heap_open(myrelid, AccessExclusiveLock);
- myrelname = pstrdup(RelationGetRelationName(myrel));
- heap_close(myrel, AccessExclusiveLock);
-
- elog(ERROR, "ALTER TABLE: relation \"%s\" not found",
- myrelname);
- }
- classtuple.t_self = reltup->t_self;
- ReleaseSysCache(reltup);
-
- switch (heap_mark4update(rel, &classtuple, &buffer))
- {
- case HeapTupleSelfUpdated:
- case HeapTupleMayBeUpdated:
- break;
- default:
- elog(ERROR, "couldn't lock pg_class tuple");
- }
- reltup = heap_copytuple(&classtuple);
- ReleaseBuffer(buffer);
-
- attrdesc = heap_openr(AttributeRelationName, RowExclusiveLock);
-
- /*
- * Get the target pg_attribute tuple and make a modifiable copy
- */
- tup = SearchSysCacheCopy(ATTNAME,
- ObjectIdGetDatum(myrelid),
- PointerGetDatum(colName),
- 0, 0);
- if (!HeapTupleIsValid(tup))
- {
- Relation myrel;
- char *myrelname;
-
- myrel = heap_open(myrelid, AccessExclusiveLock);
- myrelname = pstrdup(RelationGetRelationName(myrel));
- heap_close(myrel, AccessExclusiveLock);
-
- elog(ERROR, "ALTER TABLE: column name \"%s\" doesn't exist in table \"%s\"",
- colName, myrelname);
- }
-
- attribute = (Form_pg_attribute) GETSTRUCT(tup);
- attnum = attribute->attnum;
- if (attnum <= 0)
- elog(ERROR, "ALTER TABLE: column name \"%s\" was already dropped",
- colName);
-
- /*
- * Check constraints/indices etc here
- */
- if (behavior != CASCADE)
- {
- if (!RemoveColumnReferences(myrelid, attnum, true, NULL))
- elog(ERROR, "the column is referenced");
- }
-
- /*
- * change the target pg_attribute tuple
- */
- sprintf(dropColname, "*already Dropped*%d", attnum);
- namestrcpy(&(attribute->attname), dropColname);
- ATTRIBUTE_DROP_COLUMN(attribute);
-
- simple_heap_update(attrdesc, &tup->t_self, tup);
- hasindex = (!IsIgnoringSystemIndexes() && RelationGetForm(attrdesc)->relhasindex);
- if (hasindex)
- {
- CatalogOpenIndices(Num_pg_attr_indices, Name_pg_attr_indices, idescs);
- CatalogIndexInsert(idescs, Num_pg_attr_indices,
- attrdesc, tup);
- CatalogCloseIndices(Num_pg_attr_indices, idescs);
- }
- heap_close(attrdesc, NoLock);
- heap_freetuple(tup);
-
- /* delete comment for this attribute only */
- CreateComments(RelationGetRelid(rel), RelOid_pg_class,
- (int32) attnum, NULL);
-
- /* delete attrdef */
- drop_default(myrelid, attnum);
-
- /*
- * Remove objects which reference this column
- */
- if (behavior == CASCADE)
- {
- Relation ridescs[Num_pg_class_indices];
-
- RemoveColumnReferences(myrelid, attnum, false, reltup);
- /* update pg_class tuple */
- simple_heap_update(rel, &reltup->t_self, reltup);
- CatalogOpenIndices(Num_pg_class_indices, Name_pg_class_indices, ridescs);
- CatalogIndexInsert(ridescs, Num_pg_class_indices, rel, reltup);
- CatalogCloseIndices(Num_pg_class_indices, ridescs);
- }
-
- heap_freetuple(reltup);
- heap_close(rel, NoLock);
-#else
elog(ERROR, "ALTER TABLE / DROP COLUMN is not implemented");
-#endif /* _DROP_COLUMN_HACK__ */
}
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