From 6d0d15c451739396851d3f93f81c63a47535bf1e Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sat, 28 Sep 2002 20:00:19 +0000
Subject: [PATCH] Make the world at least somewhat safe for zero-column tables,
and remove the special case in ALTER DROP COLUMN to prohibit dropping a
table's last column.
---
src/backend/access/common/tupdesc.c | 65 ++++++++++++++---------
src/backend/commands/tablecmds.c | 29 ++--------
src/backend/executor/execTuples.c | 17 ++----
src/backend/executor/nodeAgg.c | 22 ++++----
src/backend/parser/parse_target.c | 6 ++-
src/test/regress/expected/alter_table.out | 6 +--
6 files changed, 64 insertions(+), 81 deletions(-)
diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index 5a1b912b379..f1f92af4725 100644
--- a/src/backend/access/common/tupdesc.c
+++ b/src/backend/access/common/tupdesc.c
@@ -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;
- size = desc->natts * sizeof(Form_pg_attribute);
- desc->attrs = (Form_pg_attribute *) palloc(size);
- for (i = 0; i < desc->natts; i++)
+ if (desc->natts > 0)
{
- desc->attrs[i] = (Form_pg_attribute) palloc(ATTRIBUTE_TUPLE_SIZE);
- memcpy(desc->attrs[i],
- tupdesc->attrs[i],
- ATTRIBUTE_TUPLE_SIZE);
- desc->attrs[i]->attnotnull = false;
- desc->attrs[i]->atthasdef = false;
+ 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);
+ 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;
- size = desc->natts * sizeof(Form_pg_attribute);
- desc->attrs = (Form_pg_attribute *) palloc(size);
- for (i = 0; i < desc->natts; i++)
+ if (desc->natts > 0)
{
- desc->attrs[i] = (Form_pg_attribute) palloc(ATTRIBUTE_TUPLE_SIZE);
- memcpy(desc->attrs[i],
- tupdesc->attrs[i],
- ATTRIBUTE_TUPLE_SIZE);
+ 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);
+ }
}
+ else
+ desc->attrs = NULL;
if (constr)
{
TupleConstr *cpy = (TupleConstr *) palloc(sizeof(TupleConstr));
@@ -197,7 +209,8 @@ FreeTupleDesc(TupleDesc tupdesc)
for (i = 0; i < tupdesc->natts; i++)
pfree(tupdesc->attrs[i]);
- pfree(tupdesc->attrs);
+ if (tupdesc->attrs)
+ pfree(tupdesc->attrs);
if (tupdesc->constr)
{
if (tupdesc->constr->num_defval > 0)
@@ -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
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 0934a274c7a..14d82630c8a 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -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);
diff --git a/src/backend/executor/execTuples.c b/src/backend/executor/execTuples.c
index 1a5f835be1d..7b0df664c74 100644
--- a/src/backend/executor/execTuples.c
+++ b/src/backend/executor/execTuples.c
@@ -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)
{
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index 898ca62a600..0ebf2f7151e 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -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);
}
}
}
diff --git a/src/backend/parser/parse_target.c b/src/backend/parser/parse_target.c
index 18d11cc7f5a..c03db4f8b4b 100644
--- a/src/backend/parser/parse_target.c
+++ b/src/backend/parser/parse_target.c
@@ -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;
diff --git a/src/test/regress/expected/alter_table.out b/src/test/regress/expected/alter_table.out
index de2e4a29757..f604c1c0dd0 100644
--- a/src/test/regress/expected/alter_table.out
+++ b/src/test/regress/expected/alter_table.out
@@ -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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