diff options
Diffstat (limited to 'src/backend/catalog/heap.c')
| -rw-r--r-- | src/backend/catalog/heap.c | 88 |
1 files changed, 80 insertions, 8 deletions
diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c index 6045c17bb6a..ec9165c55b1 100644 --- a/src/backend/catalog/heap.c +++ b/src/backend/catalog/heap.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/catalog/heap.c,v 1.214 2002/07/31 17:19:51 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/catalog/heap.c,v 1.215 2002/08/02 18:15:05 tgl Exp $ * * * INTERFACE ROUTINES @@ -97,37 +97,37 @@ static void RemoveStatistics(Relation rel); static FormData_pg_attribute a1 = { 0, {"ctid"}, TIDOID, 0, sizeof(ItemPointerData), SelfItemPointerAttributeNumber, 0, -1, -1, - false, 'p', false, 'i', true, false + false, 'p', false, 'i', true, false, false }; static FormData_pg_attribute a2 = { 0, {"oid"}, OIDOID, 0, sizeof(Oid), ObjectIdAttributeNumber, 0, -1, -1, - true, 'p', false, 'i', true, false + true, 'p', false, 'i', true, false, false }; static FormData_pg_attribute a3 = { 0, {"xmin"}, XIDOID, 0, sizeof(TransactionId), MinTransactionIdAttributeNumber, 0, -1, -1, - true, 'p', false, 'i', true, false + true, 'p', false, 'i', true, false, false }; static FormData_pg_attribute a4 = { 0, {"cmin"}, CIDOID, 0, sizeof(CommandId), MinCommandIdAttributeNumber, 0, -1, -1, - true, 'p', false, 'i', true, false + true, 'p', false, 'i', true, false, false }; static FormData_pg_attribute a5 = { 0, {"xmax"}, XIDOID, 0, sizeof(TransactionId), MaxTransactionIdAttributeNumber, 0, -1, -1, - true, 'p', false, 'i', true, false + true, 'p', false, 'i', true, false, false }; static FormData_pg_attribute a6 = { 0, {"cmax"}, CIDOID, 0, sizeof(CommandId), MaxCommandIdAttributeNumber, 0, -1, -1, - true, 'p', false, 'i', true, false + true, 'p', false, 'i', true, false, false }; /* @@ -139,7 +139,7 @@ static FormData_pg_attribute a6 = { static FormData_pg_attribute a7 = { 0, {"tableoid"}, OIDOID, 0, sizeof(Oid), TableOidAttributeNumber, 0, -1, -1, - true, 'p', false, 'i', true, false + true, 'p', false, 'i', true, false, false }; static Form_pg_attribute SysAtt[] = {&a1, &a2, &a3, &a4, &a5, &a6, &a7}; @@ -893,6 +893,78 @@ DeleteAttributeTuples(Oid relid) } /* + * RemoveAttributeById + * + * This is the guts of ALTER TABLE DROP COLUMN: actually mark the attribute + * deleted in pg_attribute. (Everything else needed, such as getting rid + * of any pg_attrdef entry, is handled by dependency.c.) + */ +void +RemoveAttributeById(Oid relid, AttrNumber attnum) +{ + Relation rel; + Relation attr_rel; + HeapTuple tuple; + Form_pg_attribute attStruct; + char newattname[NAMEDATALEN]; + + /* + * Grab an exclusive lock on the target table, which we will NOT + * release until end of transaction. (In the simple case where + * we are directly dropping this column, AlterTableDropColumn already + * did this ... but when cascading from a drop of some other object, + * we may not have any lock.) + */ + rel = heap_open(relid, AccessExclusiveLock); + + attr_rel = heap_openr(AttributeRelationName, RowExclusiveLock); + + tuple = SearchSysCacheCopy(ATTNUM, + ObjectIdGetDatum(relid), + Int16GetDatum(attnum), + 0, 0); + if (!HeapTupleIsValid(tuple)) /* shouldn't happen */ + elog(ERROR, "RemoveAttributeById: Failed to find attribute %d in relation %u", + attnum, relid); + attStruct = (Form_pg_attribute) GETSTRUCT(tuple); + + /* Mark the attribute as dropped */ + attStruct->attisdropped = true; + + /* Remove any NOT NULL constraint the column may have */ + attStruct->attnotnull = false; + + /* We don't want to keep stats for it anymore */ + attStruct->attstattarget = 0; + + /* Change the column name to something that isn't likely to conflict */ + snprintf(newattname, NAMEDATALEN, "........pg.dropped.%d........", attnum); + namestrcpy(&(attStruct->attname), newattname); + + simple_heap_update(attr_rel, &tuple->t_self, tuple); + + /* keep the system catalog indices current */ + if (RelationGetForm(attr_rel)->relhasindex) + { + Relation idescs[Num_pg_attr_indices]; + + CatalogOpenIndices(Num_pg_attr_indices, Name_pg_attr_indices, idescs); + CatalogIndexInsert(idescs, Num_pg_attr_indices, attr_rel, tuple); + CatalogCloseIndices(Num_pg_attr_indices, idescs); + } + + /* + * Because updating the pg_attribute row will trigger a relcache flush + * for the target relation, we need not do anything else to notify + * other backends of the change. + */ + + heap_close(attr_rel, RowExclusiveLock); + + heap_close(rel, NoLock); +} + +/* * RemoveAttrDefault * * If the specified relation/attribute has a default, remove it. |