rowenc: fix decoding for Canonical types

The definition of a Canonical type is the Canonical type is the type of
the datum that a column decodes into. This was only partially true for
the two canonical types that use the oid wrapper. The citext type was
decoded by the value side decoder, but not the keyside decoder. The name
type was decoded by the key side decoder, but not the value side
decoder.

Release note: none
Epic: CRDB-48647

Author: jeffswenson

pkg/sql/randgen/type.go

@@ -117,6 +117,9 @@ func RandTypeFromSlice(rng *rand.Rand, typs []*types.T) *types.T {
 	case types.BitFamily:
 		return types.MakeBit(int32(rng.Intn(50)))
 	case types.CollatedStringFamily:
+		if typ.Oid() == oidext.T_citext {
+			return types.CIText
+		}
 		return types.MakeCollatedString(types.String, *RandCollationLocale(rng))
 	case types.ArrayFamily:
 		if typ.ArrayContents().Family() == types.AnyFamily {

pkg/sql/rowenc/encoded_datum_test.go

@@ -17,13 +17,15 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/sql/catalog/colinfo"
 	"github.com/cockroachdb/cockroach/pkg/sql/randgen"
 	"github.com/cockroachdb/cockroach/pkg/sql/rowenc"
+	"github.com/cockroachdb/cockroach/pkg/sql/rowenc/keyside"
 	"github.com/cockroachdb/cockroach/pkg/sql/rowenc/valueside"
 	"github.com/cockroachdb/cockroach/pkg/sql/sem/eval"
 	"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
 	"github.com/cockroachdb/cockroach/pkg/sql/types"
 	"github.com/cockroachdb/cockroach/pkg/util/encoding"
 	"github.com/cockroachdb/cockroach/pkg/util/leaktest"
 	"github.com/cockroachdb/cockroach/pkg/util/randutil"
+	"github.com/stretchr/testify/require"
 )
 
 func TestEncDatum(t *testing.T) {
@@ -150,7 +152,6 @@ func TestEncDatumNull(t *testing.T) {
 			}
 		}
 	}
-
 }
 
 // checkEncDatumCmp encodes the given values using the given encodings,
@@ -770,6 +771,41 @@ func TestEncDatumFingerprintMemory(t *testing.T) {
 	}
 }
 
+func TestDecodesToCanonical(t *testing.T) {
+	rng, _ := randutil.NewTestRand()
+	for i := 0; i < 20; i++ {
+		typ := randgen.RandType(rng)
+		datum := randgen.RandDatum(rng, typ, false)
+
+		buf, err := valueside.Encode(nil, valueside.NoColumnID, datum)
+		require.NoError(t, err)
+		decoded, _, err := valueside.Decode(&tree.DatumAlloc{}, typ, buf)
+
+		valueType := decoded.ResolvedType()
+		require.NoError(t, err)
+		require.True(t, valueType.Identical(typ.Canonical()), "value type %+v not identical to canonical type %+v", valueType, typ)
+		require.Equal(t, decoded.ResolvedType().Oid(), typ.Canonical().Oid())
+
+		direction := encoding.Ascending
+		if rng.Int()%2 == 0 {
+			direction = encoding.Descending
+		}
+
+		if colinfo.ColumnTypeIsIndexable(typ) {
+			buf, err = keyside.Encode(nil, datum, direction)
+			require.NoError(t, err)
+
+			decodedKey, _, err := keyside.Decode(&tree.DatumAlloc{}, typ, buf, direction)
+			require.NoError(t, err)
+
+			keyType := decodedKey.ResolvedType()
+			require.NoError(t, err)
+			require.True(t, keyType.Identical(typ.Canonical()), "key type %+v not identical to canonical type %+v", keyType, typ)
+			require.Equal(t, decodedKey.ResolvedType().Oid(), typ.Canonical().Oid())
+		}
+	}
+}
+
 func encDatumFromEncodedWithDatum(
 	enc catenumpb.DatumEncoding, encoded []byte, datum tree.Datum,
 ) rowenc.EncDatum {

pkg/sql/rowenc/keyside/BUILD.bazel

@@ -14,6 +14,7 @@ go_library(
     deps = [
         "//pkg/geo",
         "//pkg/geo/geopb",
+        "//pkg/sql/oidext",
         "//pkg/sql/pgrepl/lsn",
         "//pkg/sql/sem/tree",
         "//pkg/sql/types",

pkg/sql/rowenc/keyside/decode.go

@@ -11,6 +11,7 @@ import (
 	"github.com/cockroachdb/apd/v3"
 	"github.com/cockroachdb/cockroach/pkg/geo"
 	"github.com/cockroachdb/cockroach/pkg/geo/geopb"
+	"github.com/cockroachdb/cockroach/pkg/sql/oidext"
 	"github.com/cockroachdb/cockroach/pkg/sql/pgrepl/lsn"
 	"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
 	"github.com/cockroachdb/cockroach/pkg/sql/types"
@@ -131,6 +132,10 @@ func Decode(
 		if err != nil {
 			return nil, nil, err
 		}
+		if valType.Oid() == oidext.T_citext {
+			d, err := a.NewDCIText(r)
+			return d, rkey, err
+		}
 		d, err := a.NewDCollatedString(r, valType.Locale())
 		return d, rkey, err
 	case types.JsonFamily:

pkg/sql/rowenc/valueside/decode.go

@@ -65,6 +65,9 @@ func DecodeUntaggedDatum(
 		if err != nil {
 			return nil, b, err
 		}
+		if t.Oid() == oid.T_name {
+			return a.NewDName(tree.DString(data)), b, nil
+		}
 		return a.NewDString(tree.DString(data)), b, nil
 	case types.CollatedStringFamily:
 		b, data, err := encoding.DecodeUntaggedBytesValue(buf)