Fix array slicing of int2vector and oidvector values.

The previous coding labeled expressions such as pg_index.indkey[1:3] as
being of int2vector type; which is not right because the subscript bounds
of such a result don't, in general, satisfy the restrictions of int2vector.
To fix, implicitly promote the result of slicing int2vector to int2[],
or oidvector to oid[].  This is similar to what we've done with domains
over arrays, which is a good analogy because these types are very much
like restricted domains of the corresponding regular-array types.

A side-effect is that we now also forbid array-element updates on such
columns, eg while "update pg_index set indkey[4] = 42" would have worked
before if you were superuser (and corrupted your catalogs irretrievably,
no doubt) it's now disallowed.  This seems like a good thing since, again,
some choices of subscripting would've led to results not satisfying the
restrictions of int2vector.  The case of an array-slice update was
rejected before, though with a different error message than you get now.
We could make these cases work in future if we added a cast from int2[]
to int2vector (with a cast function checking the subscript restrictions)
but it seems unlikely that there's any value in that.

Per report from Ronan Dunklau.  Back-patch to all supported branches
because of the crash risks involved.

diff --git a/src/backend/parser/parse_node.c b/src/backend/parser/parse_node.c
index 6ffbd76727519da5416f153ccd605be69e48c6a6..e0ea43a8104285274cbf81bf38369322d36c938a 100644 (file)
--- a/src/backend/parser/parse_node.c
+++ b/src/backend/parser/parse_node.c
@@ -226,6 +226,18 @@ transformArrayType(Oid *arrayType, int32 *arrayTypmod)
         */
        *arrayType = getBaseTypeAndTypmod(*arrayType, arrayTypmod);
 
+       /*
+        * We treat int2vector and oidvector as though they were domains over
+        * int2[] and oid[].  This is needed because array slicing could create an
+        * array that doesn't satisfy the dimensionality constraints of the
+        * xxxvector type; so we want the result of a slice operation to be
+        * considered to be of the more general type.
+        */
+       if (*arrayType == INT2VECTOROID)
+               *arrayType = INT2ARRAYOID;
+       else if (*arrayType == OIDVECTOROID)
+               *arrayType = OIDARRAYOID;
+
        /* Get the type tuple for the array */
        type_tuple_array = SearchSysCache1(TYPEOID, ObjectIdGetDatum(*arrayType));
        if (!HeapTupleIsValid(type_tuple_array))
@@ -263,6 +275,7 @@ transformArrayType(Oid *arrayType, int32 *arrayTypmod)
  * For both cases, if the source array is of a domain-over-array type,
  * the result is of the base array type or its element type; essentially,
  * we must fold a domain to its base type before applying subscripting.
+ * (Note that int2vector and oidvector are treated as domains here.)
  *
  * pstate              Parse state
  * arrayBase   Already-transformed expression for the array as a whole

diff --git a/src/backend/parser/parse_target.c b/src/backend/parser/parse_target.c
index 9c6c202c8e6ef16a981fdafa8945741ca70cd709..d56e00ffde6617a4d00f5c94d228d4018ab4f56a 100644 (file)
--- a/src/backend/parser/parse_target.c
+++ b/src/backend/parser/parse_target.c
@@ -839,18 +839,20 @@ transformAssignmentSubscripts(ParseState *pstate,
        /* If target was a domain over array, need to coerce up to the domain */
        if (arrayType != targetTypeId)
        {
+               Oid                     resulttype = exprType(result);
+
                result = coerce_to_target_type(pstate,
-                                                                          result, exprType(result),
+                                                                          result, resulttype,
                                                                           targetTypeId, targetTypMod,
                                                                           COERCION_ASSIGNMENT,
                                                                           COERCE_IMPLICIT_CAST,
                                                                           -1);
-               /* probably shouldn't fail, but check */
+               /* can fail if we had int2vector/oidvector, but not for true domains */
                if (result == NULL)
                        ereport(ERROR,
                                        (errcode(ERRCODE_CANNOT_COERCE),
                                         errmsg("cannot cast type %s to %s",
-                                                       format_type_be(exprType(result)),
+                                                       format_type_be(resulttype),
                                                        format_type_be(targetTypeId)),
                                         parser_errposition(pstate, location)));
        }

diff --git a/src/include/catalog/pg_type.h b/src/include/catalog/pg_type.h
index 20813125ab22ae349eee5077057aeb3e9556ac0d..a2be2c404b1589b95bfb5a37f25a8f3035b3b9c6 100644 (file)
--- a/src/include/catalog/pg_type.h
+++ b/src/include/catalog/pg_type.h
@@ -446,6 +446,7 @@ DATA(insert OID = 1001 (  _bytea     PGNSP PGUID -1 f b A f t \054 0        17 0 array_in
 DATA(insert OID = 1002 (  _char                 PGNSP PGUID -1 f b A f t \054 0        18 0 array_in array_out array_recv array_send - - array_typanalyze i x f 0 -1 0 0 _null_ _null_ _null_ ));
 DATA(insert OID = 1003 (  _name                 PGNSP PGUID -1 f b A f t \054 0        19 0 array_in array_out array_recv array_send - - array_typanalyze i x f 0 -1 0 0 _null_ _null_ _null_ ));
 DATA(insert OID = 1005 (  _int2                 PGNSP PGUID -1 f b A f t \054 0        21 0 array_in array_out array_recv array_send - - array_typanalyze i x f 0 -1 0 0 _null_ _null_ _null_ ));
+#define INT2ARRAYOID           1005
 DATA(insert OID = 1006 (  _int2vector PGNSP PGUID -1 f b A f t \054 0  22 0 array_in array_out array_recv array_send - - array_typanalyze i x f 0 -1 0 0 _null_ _null_ _null_ ));
 DATA(insert OID = 1007 (  _int4                 PGNSP PGUID -1 f b A f t \054 0        23 0 array_in array_out array_recv array_send - - array_typanalyze i x f 0 -1 0 0 _null_ _null_ _null_ ));
 #define INT4ARRAYOID           1007
@@ -453,6 +454,7 @@ DATA(insert OID = 1008 (  _regproc   PGNSP PGUID -1 f b A f t \054 0        24 0 array_i
 DATA(insert OID = 1009 (  _text                 PGNSP PGUID -1 f b A f t \054 0        25 0 array_in array_out array_recv array_send - - array_typanalyze i x f 0 -1 0 100 _null_ _null_ _null_ ));
 #define TEXTARRAYOID           1009
 DATA(insert OID = 1028 (  _oid          PGNSP PGUID -1 f b A f t \054 0        26 0 array_in array_out array_recv array_send - - array_typanalyze i x f 0 -1 0 0 _null_ _null_ _null_ ));
+#define OIDARRAYOID                    1028
 DATA(insert OID = 1010 (  _tid          PGNSP PGUID -1 f b A f t \054 0        27 0 array_in array_out array_recv array_send - - array_typanalyze i x f 0 -1 0 0 _null_ _null_ _null_ ));
 DATA(insert OID = 1011 (  _xid          PGNSP PGUID -1 f b A f t \054 0        28 0 array_in array_out array_recv array_send - - array_typanalyze i x f 0 -1 0 0 _null_ _null_ _null_ ));
 DATA(insert OID = 1012 (  _cid          PGNSP PGUID -1 f b A f t \054 0        29 0 array_in array_out array_recv array_send - - array_typanalyze i x f 0 -1 0 0 _null_ _null_ _null_ ));