Function TestUniqueGlobalIndexKeyWithNullValues

pkg/tablecodec/tablecodec_test.go:826–975

TestUniqueGlobalIndexKeyWithNullValues tests that for unique global indexes on non-clustered tables: - Non-NULL values do NOT have partition ID in the key (distinct = true) - NULL values DO have partition ID in the key (distinct = false) - Partition ID is always in the value for global indexes This

(t *testing.T)

// - Partition ID is always in the value for global indexes
// This is critical after EXCHANGE PARTITION where duplicate _tidb_rowid values can exist.
func TestUniqueGlobalIndexKeyWithNullValues(t *testing.T) {
	tableID := int64(100)
	partitionID := int64(42)
	handleID := int64(999)

	// Build a simple TableInfo and IndexInfo for a unique global index
	// on a non-clustered table (no clustered index)
	tblInfo := &model.TableInfo{
		ID:   tableID,
		Name: pmodel.NewCIStr("test_table"),
		Columns: []*model.ColumnInfo{
			{
				ID:        1,
				Name:      pmodel.NewCIStr("a"),
				Offset:    0,
				FieldType: *types.NewFieldType(mysql.TypeLong),
			},
			{
				ID:        2,
				Name:      pmodel.NewCIStr("b"),
				Offset:    1,
				FieldType: *types.NewFieldType(mysql.TypeLong),
			},
		},
		// Non-clustered table (PKIsHandle = false, IsCommonHandle = false)
		PKIsHandle:     false,
		IsCommonHandle: false,
	}

	idxInfo := &model.IndexInfo{
		ID:   1,
		Name: pmodel.NewCIStr("idx_b"),
		Columns: []*model.IndexColumn{
			{
				Name:   pmodel.NewCIStr("b"),
				Offset: 1,
				Length: types.UnspecifiedLength,
			},
		},
		Unique:             true,
		Global:             true,
		GlobalIndexVersion: model.GlobalIndexVersionV1,
		State:              model.StatePublic,
	}

	loc := time.UTC

	// For unique index with non-NULL values, distinct = true,
	// so the handle is NOT encoded in the key at all.
	indexedValues := []types.Datum{types.NewIntDatum(123)}
	handle := kv.NewPartitionHandle(partitionID, kv.IntHandle(handleID))

	key, distinct, err := GenIndexKey(loc, tblInfo, idxInfo, tableID, indexedValues, handle, nil)
	require.NoError(t, err)
	require.True(t, distinct, "unique index with non-NULL value should be distinct")

	// The key should NOT contain the partition ID flag since distinct = true
	// means no handle (and thus no partition ID) is encoded in the key