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Commit6d0d15c

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committed
Make the world at least somewhat safe for zero-column tables, and
remove the special case in ALTER DROP COLUMN to prohibit dropping atable's last column.
1 parent23616b4 commit6d0d15c

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6 files changed

+64
-81
lines changed

6 files changed

+64
-81
lines changed

‎src/backend/access/common/tupdesc.c‎

Lines changed: 39 additions & 26 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/access/common/tupdesc.c,v 1.90 2002/09/22 19:42:50 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/access/common/tupdesc.c,v 1.91 2002/09/28 20:00:18 tgl Exp $
1212
*
1313
* NOTES
1414
* some of the executor utility code such as "ExecTypeFromTL" should be
@@ -39,28 +39,34 @@
3939
TupleDesc
4040
CreateTemplateTupleDesc(intnatts,boolhasoid)
4141
{
42-
uint32size;
4342
TupleDescdesc;
4443

4544
/*
4645
* sanity checks
4746
*/
48-
AssertArg(natts >=1);
47+
AssertArg(natts >=0);
4948

5049
/*
5150
* allocate enough memory for the tuple descriptor and zero it as
5251
* TupleDescInitEntry assumes that the descriptor is filled with NULL
5352
* pointers.
5453
*/
55-
size=natts*sizeof(Form_pg_attribute);
5654
desc= (TupleDesc)palloc(sizeof(structtupleDesc));
57-
desc->attrs= (Form_pg_attribute*)palloc(size);
58-
desc->constr=NULL;
59-
MemSet(desc->attrs,0,size);
6055

6156
desc->natts=natts;
6257
desc->tdhasoid=hasoid;
6358

59+
if (natts>0)
60+
{
61+
uint32size=natts*sizeof(Form_pg_attribute);
62+
63+
desc->attrs= (Form_pg_attribute*)palloc(size);
64+
MemSet(desc->attrs,0,size);
65+
}
66+
else
67+
desc->attrs=NULL;
68+
desc->constr=NULL;
69+
6470
returndesc;
6571
}
6672

@@ -79,7 +85,7 @@ CreateTupleDesc(int natts, bool hasoid, Form_pg_attribute *attrs)
7985
/*
8086
* sanity checks
8187
*/
82-
AssertArg(natts >=1);
88+
AssertArg(natts >=0);
8389

8490
desc= (TupleDesc)palloc(sizeof(structtupleDesc));
8591
desc->attrs=attrs;
@@ -108,17 +114,20 @@ CreateTupleDescCopy(TupleDesc tupdesc)
108114

109115
desc= (TupleDesc)palloc(sizeof(structtupleDesc));
110116
desc->natts=tupdesc->natts;
111-
size=desc->natts*sizeof(Form_pg_attribute);
112-
desc->attrs= (Form_pg_attribute*)palloc(size);
113-
for (i=0;i<desc->natts;i++)
117+
if (desc->natts>0)
114118
{
115-
desc->attrs[i]= (Form_pg_attribute)palloc(ATTRIBUTE_TUPLE_SIZE);
116-
memcpy(desc->attrs[i],
117-
tupdesc->attrs[i],
118-
ATTRIBUTE_TUPLE_SIZE);
119-
desc->attrs[i]->attnotnull= false;
120-
desc->attrs[i]->atthasdef= false;
119+
size=desc->natts*sizeof(Form_pg_attribute);
120+
desc->attrs= (Form_pg_attribute*)palloc(size);
121+
for (i=0;i<desc->natts;i++)
122+
{
123+
desc->attrs[i]= (Form_pg_attribute)palloc(ATTRIBUTE_TUPLE_SIZE);
124+
memcpy(desc->attrs[i],tupdesc->attrs[i],ATTRIBUTE_TUPLE_SIZE);
125+
desc->attrs[i]->attnotnull= false;
126+
desc->attrs[i]->atthasdef= false;
127+
}
121128
}
129+
else
130+
desc->attrs=NULL;
122131
desc->constr=NULL;
123132
desc->tdhasoid=tupdesc->tdhasoid;
124133

@@ -142,15 +151,18 @@ CreateTupleDescCopyConstr(TupleDesc tupdesc)
142151

143152
desc= (TupleDesc)palloc(sizeof(structtupleDesc));
144153
desc->natts=tupdesc->natts;
145-
size=desc->natts*sizeof(Form_pg_attribute);
146-
desc->attrs= (Form_pg_attribute*)palloc(size);
147-
for (i=0;i<desc->natts;i++)
154+
if (desc->natts>0)
148155
{
149-
desc->attrs[i]= (Form_pg_attribute)palloc(ATTRIBUTE_TUPLE_SIZE);
150-
memcpy(desc->attrs[i],
151-
tupdesc->attrs[i],
152-
ATTRIBUTE_TUPLE_SIZE);
156+
size=desc->natts*sizeof(Form_pg_attribute);
157+
desc->attrs= (Form_pg_attribute*)palloc(size);
158+
for (i=0;i<desc->natts;i++)
159+
{
160+
desc->attrs[i]= (Form_pg_attribute)palloc(ATTRIBUTE_TUPLE_SIZE);
161+
memcpy(desc->attrs[i],tupdesc->attrs[i],ATTRIBUTE_TUPLE_SIZE);
162+
}
153163
}
164+
else
165+
desc->attrs=NULL;
154166
if (constr)
155167
{
156168
TupleConstr*cpy= (TupleConstr*)palloc(sizeof(TupleConstr));
@@ -197,7 +209,8 @@ FreeTupleDesc(TupleDesc tupdesc)
197209

198210
for (i=0;i<tupdesc->natts;i++)
199211
pfree(tupdesc->attrs[i]);
200-
pfree(tupdesc->attrs);
212+
if (tupdesc->attrs)
213+
pfree(tupdesc->attrs);
201214
if (tupdesc->constr)
202215
{
203216
if (tupdesc->constr->num_defval>0)
@@ -228,7 +241,6 @@ FreeTupleDesc(TupleDesc tupdesc)
228241
}
229242

230243
pfree(tupdesc);
231-
232244
}
233245

234246
/*
@@ -361,6 +373,7 @@ TupleDescInitEntry(TupleDesc desc,
361373
*/
362374
AssertArg(PointerIsValid(desc));
363375
AssertArg(attributeNumber >=1);
376+
AssertArg(attributeNumber <=desc->natts);
364377

365378
/*
366379
* attributeName's are sometimes NULL, from resdom's. I don't know

‎src/backend/commands/tablecmds.c‎

Lines changed: 3 additions & 26 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v 1.44 2002/09/23 20:43:40 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v 1.45 2002/09/28 20:00:19 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -2331,9 +2331,7 @@ AlterTableDropColumn(Oid myrelid, bool recurse, bool recursing,
23312331
{
23322332
Relationrel;
23332333
AttrNumberattnum;
2334-
AttrNumbern;
23352334
TupleDesctupleDesc;
2336-
boolsuccess;
23372335
ObjectAddressobject;
23382336

23392337
rel=heap_open(myrelid,AccessExclusiveLock);
@@ -2359,34 +2357,13 @@ AlterTableDropColumn(Oid myrelid, bool recurse, bool recursing,
23592357
RelationGetRelationName(rel),colName);
23602358

23612359
/* Can't drop a system attribute */
2360+
/* XXX perhaps someday allow dropping OID? */
23622361
if (attnum<0)
23632362
elog(ERROR,"ALTER TABLE: Cannot drop system attribute \"%s\"",
23642363
colName);
23652364

2366-
/*
2367-
* Make sure there will be at least one user column left in the
2368-
* relation after we drop this one. Zero-length tuples tend to
2369-
* confuse us.
2370-
*/
2371-
tupleDesc=RelationGetDescr(rel);
2372-
2373-
success= false;
2374-
for (n=1;n <=tupleDesc->natts;n++)
2375-
{
2376-
Form_pg_attributeattribute=tupleDesc->attrs[n-1];
2377-
2378-
if (!attribute->attisdropped&&n!=attnum)
2379-
{
2380-
success= true;
2381-
break;
2382-
}
2383-
}
2384-
2385-
if (!success)
2386-
elog(ERROR,"ALTER TABLE: Cannot drop last column from table \"%s\"",
2387-
RelationGetRelationName(rel));
2388-
23892365
/* Don't drop inherited columns */
2366+
tupleDesc=RelationGetDescr(rel);
23902367
if (tupleDesc->attrs[attnum-1]->attinhcount>0&& !recursing)
23912368
elog(ERROR,"ALTER TABLE: Cannot drop inherited column \"%s\"",
23922369
colName);

‎src/backend/executor/execTuples.c‎

Lines changed: 5 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -15,7 +15,7 @@
1515
*
1616
*
1717
* IDENTIFICATION
18-
* $Header: /cvsroot/pgsql/src/backend/executor/execTuples.c,v 1.59 2002/09/04 20:31:17 momjian Exp $
18+
* $Header: /cvsroot/pgsql/src/backend/executor/execTuples.c,v 1.60 2002/09/28 20:00:19 tgl Exp $
1919
*
2020
*-------------------------------------------------------------------------
2121
*/
@@ -560,23 +560,14 @@ ExecInitNullTupleSlot(EState *estate, TupleDesc tupType)
560560
TupleDesc
561561
ExecTypeFromTL(List*targetList,boolhasoid)
562562
{
563-
List*tlitem;
564563
TupleDesctypeInfo;
565-
Resdom*resdom;
566-
Oidrestype;
564+
List*tlitem;
567565
intlen;
568566

569-
/*
570-
* examine targetlist - if empty then return NULL
571-
*/
572-
len=ExecTargetListLength(targetList);
573-
574-
if (len==0)
575-
returnNULL;
576-
577567
/*
578568
* allocate a new typeInfo
579569
*/
570+
len=ExecTargetListLength(targetList);
580571
typeInfo=CreateTemplateTupleDesc(len,hasoid);
581572

582573
/*
@@ -585,6 +576,8 @@ ExecTypeFromTL(List *targetList, bool hasoid)
585576
foreach(tlitem,targetList)
586577
{
587578
TargetEntry*tle=lfirst(tlitem);
579+
Resdom*resdom;
580+
Oidrestype;
588581

589582
if (tle->resdom!=NULL)
590583
{

‎src/backend/executor/nodeAgg.c‎

Lines changed: 11 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -46,7 +46,7 @@
4646
* Portions Copyright (c) 1994, Regents of the University of California
4747
*
4848
* IDENTIFICATION
49-
* $Header: /cvsroot/pgsql/src/backend/executor/nodeAgg.c,v 1.87 2002/09/18 21:35:20 tgl Exp $
49+
* $Header: /cvsroot/pgsql/src/backend/executor/nodeAgg.c,v 1.88 2002/09/28 20:00:19 tgl Exp $
5050
*
5151
*-------------------------------------------------------------------------
5252
*/
@@ -658,20 +658,20 @@ ExecAgg(Agg *node)
658658
if (inputTuple==NULL)
659659
{
660660
TupleDesctupType;
661-
Datum*tupValue;
662-
char*null_array;
663-
AttrNumberattnum;
661+
Datum*dvalues;
662+
char*dnulls;
664663

665664
tupType=aggstate->csstate.css_ScanTupleSlot->ttc_tupleDescriptor;
666-
tupValue=projInfo->pi_tupValue;
667665
/* watch out for null input tuples, though... */
668-
if (tupType&&tupValue)
666+
if (tupType&&tupType->natts>0)
669667
{
670-
null_array= (char*)palloc(sizeof(char)*tupType->natts);
671-
for (attnum=0;attnum<tupType->natts;attnum++)
672-
null_array[attnum]='n';
673-
inputTuple=heap_formtuple(tupType,tupValue,null_array);
674-
pfree(null_array);
668+
dvalues= (Datum*)palloc(sizeof(Datum)*tupType->natts);
669+
dnulls= (char*)palloc(sizeof(char)*tupType->natts);
670+
MemSet(dvalues,0,sizeof(Datum)*tupType->natts);
671+
MemSet(dnulls,'n',sizeof(char)*tupType->natts);
672+
inputTuple=heap_formtuple(tupType,dvalues,dnulls);
673+
pfree(dvalues);
674+
pfree(dnulls);
675675
}
676676
}
677677
}

‎src/backend/parser/parse_target.c‎

Lines changed: 4 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/parser/parse_target.c,v 1.90 2002/09/18 21:35:22 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/parser/parse_target.c,v 1.91 2002/09/28 20:00:19 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -386,6 +386,7 @@ static List *
386386
ExpandAllTables(ParseState*pstate)
387387
{
388388
List*target=NIL;
389+
boolfound_table= false;
389390
List*ns;
390391

391392
foreach(ns,pstate->p_namespace)
@@ -413,11 +414,12 @@ ExpandAllTables(ParseState *pstate)
413414
if (!rte->inFromCl)
414415
continue;
415416

417+
found_table= true;
416418
target=nconc(target,expandRelAttrs(pstate,rte));
417419
}
418420

419421
/* Check for SELECT *; */
420-
if (target==NIL)
422+
if (!found_table)
421423
elog(ERROR,"Wildcard with no tables specified not allowed");
422424

423425
returntarget;

‎src/test/regress/expected/alter_table.out‎

Lines changed: 2 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -939,11 +939,9 @@ drop table test2;
939939
alter table atacc1 drop c;
940940
alter table atacc1 drop d;
941941
alter table atacc1 drop b;
942-
ERROR: ALTER TABLE: Cannot drop last column from table "atacc1"
943942
select * from atacc1;
944-
b
945-
----
946-
21
943+
944+
--
947945
(1 row)
948946

949947
drop table atacc1;

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