Function EncodeUniqueIndexValuesForKey

pkg/planner/core/util.go:369–414

EncodeUniqueIndexValuesForKey encodes unique index values for a key.

(ctx sessionctx.Context, tblInfo *model.TableInfo, idxInfo *model.IndexInfo, idxVals []types.Datum)

// EncodeUniqueIndexValuesForKey encodes unique index values for a key.
func EncodeUniqueIndexValuesForKey(ctx sessionctx.Context, tblInfo *model.TableInfo, idxInfo *model.IndexInfo, idxVals []types.Datum) (_ []byte, err error) {
	sc := ctx.GetSessionVars().StmtCtx
	for i := range idxVals {
		colInfo := tblInfo.Columns[idxInfo.Columns[i].Offset]
		// table.CastValue will append 0x0 if the string value's length is smaller than the BINARY column's length.
		// So we don't use CastValue for string value for now.
		// TODO: The first if branch should have been removed, because the functionality of set the collation of the datum
		// have been moved to util/ranger (normal path) and getNameValuePairs/getPointGetValue (fast path). But this change
		// will be cherry-picked to a hotfix, so we choose to be a bit conservative and keep this for now.
		if colInfo.GetType() == mysql.TypeString || colInfo.GetType() == mysql.TypeVarString || colInfo.GetType() == mysql.TypeVarchar {
			var str string
			str, err = idxVals[i].ToString()
			idxVals[i].SetString(str, idxVals[i].Collation())
		} else if colInfo.GetType() == mysql.TypeEnum && (idxVals[i].Kind() == types.KindString || idxVals[i].Kind() == types.KindBytes || idxVals[i].Kind() == types.KindBinaryLiteral) {
			var str string
			var e types.Enum
			str, err = idxVals[i].ToString()
			if err != nil {
				return nil, kv.ErrNotExist
			}
			e, err = types.ParseEnumName(colInfo.FieldType.GetElems(), str, colInfo.FieldType.GetCollate())
			if err != nil {
				return nil, kv.ErrNotExist
			}
			idxVals[i].SetMysqlEnum(e, colInfo.FieldType.GetCollate())
		} else {
			// If a truncated error or an overflow error is thrown when converting the type of `idxVal[i]` to
			// the type of `colInfo`, the `idxVal` does not exist in the `idxInfo` for sure.
			idxVals[i], err = table.CastValue(ctx, idxVals[i], colInfo, true, false)
			if types.ErrOverflow.Equal(err) || types.ErrDataTooLong.Equal(err) ||
				types.ErrTruncated.Equal(err) || types.ErrTruncatedWrongVal.Equal(err) {
				return nil, kv.ErrNotExist
			}
		}
		if err != nil {
			return nil, err
		}
	}

	encodedIdxVals, err := codec.EncodeKey(sc.TimeZone(), nil, idxVals...)
	err = sc.HandleError(err)
	if err != nil {
		return nil, err
	}
	return encodedIdxVals, nil
}

func getLowerDB(dbName pmodel.CIStr, vars *variable.SessionVars) string {
	dbNameL := dbName.L