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Make the world at least somewhat safe for zero-column tables, and

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remove the special case in ALTER DROP COLUMN to prohibit dropping a
table's last column.
REL7_3_STABLE
Tom Lane 23 years ago
parent 23616b47d5
commit 6d0d15c451
6 changed files with 64 additions and 81 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 43
      src/backend/access/common/tupdesc.c
  2. 29
      src/backend/commands/tablecmds.c
  3. 17
      src/backend/executor/execTuples.c
  4. 22
      src/backend/executor/nodeAgg.c
  5. 6
      src/backend/parser/parse_target.c
  6. 6
      src/test/regress/expected/alter_table.out

43
src/backend/access/common/tupdesc.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/access/common/tupdesc.c,v 1.90 2002/09/22 19:42:50 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/access/common/tupdesc.c,v 1.91 2002/09/28 20:00:18 tgl Exp $
*
* NOTES
* some of the executor utility code such as "ExecTypeFromTL" should be
@ -39,28 +39,34 @@
TupleDesc
CreateTemplateTupleDesc(int natts, bool hasoid)
{
uint32 size;
TupleDesc desc;
/*
* sanity checks
*/
AssertArg(natts >= 1);
AssertArg(natts >= 0);
/*
* allocate enough memory for the tuple descriptor and zero it as
* TupleDescInitEntry assumes that the descriptor is filled with NULL
* pointers.
*/
size = natts * sizeof(Form_pg_attribute);
desc = (TupleDesc) palloc(sizeof(struct tupleDesc));
desc->attrs = (Form_pg_attribute *) palloc(size);
desc->constr = NULL;
MemSet(desc->attrs, 0, size);
desc->natts = natts;
desc->tdhasoid = hasoid;
if (natts > 0)
{
uint32 size = natts * sizeof(Form_pg_attribute);
desc->attrs = (Form_pg_attribute *) palloc(size);
MemSet(desc->attrs, 0, size);
}
else
desc->attrs = NULL;
desc->constr = NULL;
return desc;
}
@ -79,7 +85,7 @@ CreateTupleDesc(int natts, bool hasoid, Form_pg_attribute *attrs)
/*
* sanity checks
*/
AssertArg(natts >= 1);
AssertArg(natts >= 0);
desc = (TupleDesc) palloc(sizeof(struct tupleDesc));
desc->attrs = attrs;
@ -108,17 +114,20 @@ CreateTupleDescCopy(TupleDesc tupdesc)
desc = (TupleDesc) palloc(sizeof(struct tupleDesc));
desc->natts = tupdesc->natts;
if (desc->natts > 0)
{
size = desc->natts * sizeof(Form_pg_attribute);
desc->attrs = (Form_pg_attribute *) palloc(size);
for (i = 0; i < desc->natts; i++)
{
desc->attrs[i] = (Form_pg_attribute) palloc(ATTRIBUTE_TUPLE_SIZE);
memcpy(desc->attrs[i],
tupdesc->attrs[i],
ATTRIBUTE_TUPLE_SIZE);
memcpy(desc->attrs[i], tupdesc->attrs[i], ATTRIBUTE_TUPLE_SIZE);
desc->attrs[i]->attnotnull = false;
desc->attrs[i]->atthasdef = false;
}
}
else
desc->attrs = NULL;
desc->constr = NULL;
desc->tdhasoid = tupdesc->tdhasoid;
@ -142,15 +151,18 @@ CreateTupleDescCopyConstr(TupleDesc tupdesc)
desc = (TupleDesc) palloc(sizeof(struct tupleDesc));
desc->natts = tupdesc->natts;
if (desc->natts > 0)
{
size = desc->natts * sizeof(Form_pg_attribute);
desc->attrs = (Form_pg_attribute *) palloc(size);
for (i = 0; i < desc->natts; i++)
{
desc->attrs[i] = (Form_pg_attribute) palloc(ATTRIBUTE_TUPLE_SIZE);
memcpy(desc->attrs[i],
tupdesc->attrs[i],
ATTRIBUTE_TUPLE_SIZE);
memcpy(desc->attrs[i], tupdesc->attrs[i], ATTRIBUTE_TUPLE_SIZE);
}
}
else
desc->attrs = NULL;
if (constr)
{
TupleConstr *cpy = (TupleConstr *) palloc(sizeof(TupleConstr));
@ -197,6 +209,7 @@ FreeTupleDesc(TupleDesc tupdesc)
for (i = 0; i < tupdesc->natts; i++)
pfree(tupdesc->attrs[i]);
if (tupdesc->attrs)
pfree(tupdesc->attrs);
if (tupdesc->constr)
{
@ -228,7 +241,6 @@ FreeTupleDesc(TupleDesc tupdesc)
}
pfree(tupdesc);
}
/*
@ -361,6 +373,7 @@ TupleDescInitEntry(TupleDesc desc,
*/
AssertArg(PointerIsValid(desc));
AssertArg(attributeNumber >= 1);
AssertArg(attributeNumber <= desc->natts);
/*
* attributeName's are sometimes NULL, from resdom's. I don't know

29
src/backend/commands/tablecmds.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v 1.44 2002/09/23 20:43:40 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v 1.45 2002/09/28 20:00:19 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -2331,9 +2331,7 @@ AlterTableDropColumn(Oid myrelid, bool recurse, bool recursing,
{
Relation rel;
AttrNumber attnum;
AttrNumber n;
TupleDesc tupleDesc;
bool success;
ObjectAddress object;
rel = heap_open(myrelid, AccessExclusiveLock);
@ -2359,34 +2357,13 @@ AlterTableDropColumn(Oid myrelid, bool recurse, bool recursing,
RelationGetRelationName(rel), colName);
/* Can't drop a system attribute */
/* XXX perhaps someday allow dropping OID? */
if (attnum < 0)
elog(ERROR, "ALTER TABLE: Cannot drop system attribute \"%s\"",
colName);
/*
* Make sure there will be at least one user column left in the
* relation after we drop this one. Zero-length tuples tend to
* confuse us.
*/
tupleDesc = RelationGetDescr(rel);
success = false;
for (n = 1; n <= tupleDesc->natts; n++)
{
Form_pg_attribute attribute = tupleDesc->attrs[n - 1];
if (!attribute->attisdropped && n != attnum)
{
success = true;
break;
}
}
if (!success)
elog(ERROR, "ALTER TABLE: Cannot drop last column from table \"%s\"",
RelationGetRelationName(rel));
/* Don't drop inherited columns */
tupleDesc = RelationGetDescr(rel);
if (tupleDesc->attrs[attnum - 1]->attinhcount > 0 && !recursing)
elog(ERROR, "ALTER TABLE: Cannot drop inherited column \"%s\"",
colName);

17
src/backend/executor/execTuples.c
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@ -15,7 +15,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/executor/execTuples.c,v 1.59 2002/09/04 20:31:17 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/executor/execTuples.c,v 1.60 2002/09/28 20:00:19 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -560,23 +560,14 @@ ExecInitNullTupleSlot(EState *estate, TupleDesc tupType)
TupleDesc
ExecTypeFromTL(List *targetList, bool hasoid)
{
List *tlitem;
TupleDesc typeInfo;
Resdom *resdom;
Oid restype;
List *tlitem;
int len;
/*
* examine targetlist - if empty then return NULL
*/
len = ExecTargetListLength(targetList);
if (len == 0)
return NULL;
/*
* allocate a new typeInfo
*/
len = ExecTargetListLength(targetList);
typeInfo = CreateTemplateTupleDesc(len, hasoid);
/*
@ -585,6 +576,8 @@ ExecTypeFromTL(List *targetList, bool hasoid)
foreach(tlitem, targetList)
{
TargetEntry *tle = lfirst(tlitem);
Resdom *resdom;
Oid restype;
if (tle->resdom != NULL)
{

22
src/backend/executor/nodeAgg.c
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@ -46,7 +46,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/executor/nodeAgg.c,v 1.87 2002/09/18 21:35:20 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/executor/nodeAgg.c,v 1.88 2002/09/28 20:00:19 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -658,20 +658,20 @@ ExecAgg(Agg *node)
if (inputTuple == NULL)
{
TupleDesc tupType;
Datum *tupValue;
char *null_array;
AttrNumber attnum;
Datum *dvalues;
char *dnulls;
tupType = aggstate->csstate.css_ScanTupleSlot->ttc_tupleDescriptor;
tupValue = projInfo->pi_tupValue;
/* watch out for null input tuples, though... */
if (tupType && tupValue)
if (tupType && tupType->natts > 0)
{
null_array = (char *) palloc(sizeof(char) * tupType->natts);
for (attnum = 0; attnum < tupType->natts; attnum++)
null_array[attnum] = 'n';
inputTuple = heap_formtuple(tupType, tupValue, null_array);
pfree(null_array);
dvalues = (Datum *) palloc(sizeof(Datum) * tupType->natts);
dnulls = (char *) palloc(sizeof(char) * tupType->natts);
MemSet(dvalues, 0, sizeof(Datum) * tupType->natts);
MemSet(dnulls, 'n', sizeof(char) * tupType->natts);
inputTuple = heap_formtuple(tupType, dvalues, dnulls);
pfree(dvalues);
pfree(dnulls);
}
}
}

6
src/backend/parser/parse_target.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/parser/parse_target.c,v 1.90 2002/09/18 21:35:22 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/parser/parse_target.c,v 1.91 2002/09/28 20:00:19 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -386,6 +386,7 @@ static List *
ExpandAllTables(ParseState *pstate)
{
List *target = NIL;
bool found_table = false;
List *ns;
foreach(ns, pstate->p_namespace)
@ -413,11 +414,12 @@ ExpandAllTables(ParseState *pstate)
if (!rte->inFromCl)
continue;
found_table = true;
target = nconc(target, expandRelAttrs(pstate, rte));
}
/* Check for SELECT *; */
if (target == NIL)
if (!found_table)
elog(ERROR, "Wildcard with no tables specified not allowed");
return target;

6
src/test/regress/expected/alter_table.out
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@ -939,11 +939,9 @@ drop table test2;
alter table atacc1 drop c;
alter table atacc1 drop d;
alter table atacc1 drop b;
ERROR: ALTER TABLE: Cannot drop last column from table "atacc1"
select * from atacc1;
b
----
21
--
(1 row)
drop table atacc1;

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