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ALTER TABLE DROP COLUMN works. Patch by Christopher Kings-Lynne,

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code review by Tom Lane.  Remaining issues: functions that take or
return tuple types are likely to break if one drops (or adds!)
a column in the table defining the type.  Need to think about what
to do here.

Along the way: some code review for recent COPY changes; mark system
columns attnotnull = true where appropriate, per discussion a month ago.
This commit is contained in:
Tom Lane
2002-08-02 18:15:10 +00:00
parent 5e6528adf7
commit 38bb77a5d1
44 changed files with 1823 additions and 891 deletions
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155
src/backend/parser/parse_relation.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/parser/parse_relation.c,v 1.70 2002/06/20 20:29:33 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/parser/parse_relation.c,v 1.71 2002/08/02 18:15:07 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -37,7 +37,9 @@ static Node *scanNameSpaceForRefname(ParseState *pstate, Node *nsnode,
static Node *scanRTEForColumn(ParseState *pstate, RangeTblEntry *rte,
char *colname);
static bool isForUpdate(ParseState *pstate, char *refname);
static int specialAttNum(char *a);
static bool get_rte_attribute_is_dropped(RangeTblEntry *rte,
AttrNumber attnum);
static int specialAttNum(const char *attname);
static void warnAutoRange(ParseState *pstate, RangeVar *relation);
@ -267,12 +269,28 @@ scanRTEForColumn(ParseState *pstate, RangeTblEntry *rte, char *colname)
/*
* Scan the user column names (or aliases) for a match. Complain if
* multiple matches.
*
* Note: because eref->colnames may include names of dropped columns,
* we need to check for non-droppedness before accepting a match.
* This takes an extra cache lookup, but we can skip the lookup most
* of the time by exploiting the knowledge that dropped columns are
* assigned dummy names starting with '.', which is an unusual choice
* for actual column names.
*
* Should the user try to fool us by altering pg_attribute.attname
* for a dropped column, we'll still catch it by virtue of the checks
* in get_rte_attribute_type(), which is called by make_var(). That
* routine has to do a cache lookup anyway, so the check there is
* cheap.
*/
foreach(c, rte->eref->colnames)
{
attnum++;
if (strcmp(strVal(lfirst(c)), colname) == 0)
{
if (colname[0] == '.' && /* see note above */
get_rte_attribute_is_dropped(rte, attnum))
continue;
if (result)
elog(ERROR, "Column reference \"%s\" is ambiguous", colname);
result = (Node *) make_var(pstate, rte, attnum);
@ -962,6 +980,9 @@ expandRTE(ParseState *pstate, RangeTblEntry *rte,
{
Form_pg_attribute attr = rel->rd_att->attrs[varattno];
if (attr->attisdropped)
continue;
if (colnames)
{
char *label;
@ -1051,6 +1072,9 @@ expandRTE(ParseState *pstate, RangeTblEntry *rte,
{
Form_pg_attribute attr = rel->rd_att->attrs[varattno];
if (attr->attisdropped)
continue;
if (colnames)
{
char *label;
@ -1246,9 +1270,16 @@ get_rte_attribute_type(RangeTblEntry *rte, AttrNumber attnum,
0, 0);
/* this shouldn't happen... */
if (!HeapTupleIsValid(tp))
elog(ERROR, "Relation %s does not have attribute %d",
elog(ERROR, "Relation \"%s\" does not have attribute %d",
get_rel_name(rte->relid), attnum);
att_tup = (Form_pg_attribute) GETSTRUCT(tp);
/*
* If dropped column, pretend it ain't there. See notes
* in scanRTEForColumn.
*/
if (att_tup->attisdropped)
elog(ERROR, "Relation \"%s\" has no column \"%s\"",
get_rel_name(rte->relid), NameStr(att_tup->attname));
*vartype = att_tup->atttypid;
*vartypmod = att_tup->atttypmod;
ReleaseSysCache(tp);
@ -1298,6 +1329,14 @@ get_rte_attribute_type(RangeTblEntry *rte, AttrNumber attnum,
elog(ERROR, "Relation %s does not have attribute %d",
get_rel_name(funcrelid), attnum);
att_tup = (Form_pg_attribute) GETSTRUCT(tp);
/*
* If dropped column, pretend it ain't there. See notes
* in scanRTEForColumn.
*/
if (att_tup->attisdropped)
elog(ERROR, "Relation \"%s\" has no column \"%s\"",
get_rel_name(funcrelid),
NameStr(att_tup->attname));
*vartype = att_tup->atttypid;
*vartypmod = att_tup->atttypmod;
ReleaseSysCache(tp);
@ -1329,6 +1368,86 @@ get_rte_attribute_type(RangeTblEntry *rte, AttrNumber attnum,
}
}
/*
* get_rte_attribute_is_dropped
* Check whether attempted attribute ref is to a dropped column
*/
static bool
get_rte_attribute_is_dropped(RangeTblEntry *rte, AttrNumber attnum)
{
bool result;
switch (rte->rtekind)
{
case RTE_RELATION:
{
/* Plain relation RTE --- get the attribute's type info */
HeapTuple tp;
Form_pg_attribute att_tup;
tp = SearchSysCache(ATTNUM,
ObjectIdGetDatum(rte->relid),
Int16GetDatum(attnum),
0, 0);
/* this shouldn't happen... */
if (!HeapTupleIsValid(tp))
elog(ERROR, "Relation \"%s\" does not have attribute %d",
get_rel_name(rte->relid), attnum);
att_tup = (Form_pg_attribute) GETSTRUCT(tp);
result = att_tup->attisdropped;
ReleaseSysCache(tp);
}
break;
case RTE_SUBQUERY:
case RTE_JOIN:
/* Subselect and join RTEs never have dropped columns */
result = false;
break;
case RTE_FUNCTION:
{
/* Function RTE */
Oid funcrettype = exprType(rte->funcexpr);
Oid funcrelid = typeidTypeRelid(funcrettype);
if (OidIsValid(funcrelid))
{
/*
* Composite data type, i.e. a table's row type
* Same as ordinary relation RTE
*/
HeapTuple tp;
Form_pg_attribute att_tup;
tp = SearchSysCache(ATTNUM,
ObjectIdGetDatum(funcrelid),
Int16GetDatum(attnum),
0, 0);
/* this shouldn't happen... */
if (!HeapTupleIsValid(tp))
elog(ERROR, "Relation %s does not have attribute %d",
get_rel_name(funcrelid), attnum);
att_tup = (Form_pg_attribute) GETSTRUCT(tp);
result = att_tup->attisdropped;
ReleaseSysCache(tp);
}
else
{
/*
* Must be a base data type, i.e. scalar
*/
result = false;
}
}
break;
default:
elog(ERROR, "get_rte_attribute_is_dropped: unsupported RTE kind %d",
(int) rte->rtekind);
result = false; /* keep compiler quiet */
}
return result;
}
/*
* given relation and att name, return id of variable
*
@ -1337,23 +1456,30 @@ get_rte_attribute_type(RangeTblEntry *rte, AttrNumber attnum,
* for access to non-opened relations.
*/
int
attnameAttNum(Relation rd, char *a)
attnameAttNum(Relation rd, const char *attname, bool sysColOK)
{
int i;
for (i = 0; i < rd->rd_rel->relnatts; i++)
if (namestrcmp(&(rd->rd_att->attrs[i]->attname), a) == 0)
return i + 1;
if ((i = specialAttNum(a)) != InvalidAttrNumber)
{
if (i != ObjectIdAttributeNumber || rd->rd_rel->relhasoids)
return i;
Form_pg_attribute att = rd->rd_att->attrs[i];
if (namestrcmp(&(att->attname), attname) == 0 && !att->attisdropped)
return i + 1;
}
if (sysColOK)
{
if ((i = specialAttNum(attname)) != InvalidAttrNumber)
{
if (i != ObjectIdAttributeNumber || rd->rd_rel->relhasoids)
return i;
}
}
/* on failure */
elog(ERROR, "Relation '%s' does not have attribute '%s'",
RelationGetRelationName(rd), a);
elog(ERROR, "Relation \"%s\" has no column \"%s\"",
RelationGetRelationName(rd), attname);
return InvalidAttrNumber; /* lint */
}
@ -1367,11 +1493,12 @@ attnameAttNum(Relation rd, char *a)
* at least in the case of "oid", which is now optional.
*/
static int
specialAttNum(char *a)
specialAttNum(const char *attname)
{
Form_pg_attribute sysatt;
sysatt = SystemAttributeByName(a, true /* "oid" will be accepted */ );
sysatt = SystemAttributeByName(attname,
true /* "oid" will be accepted */ );
if (sysatt != NULL)
return sysatt->attnum;
return InvalidAttrNumber;