// ScanIndexData scans the index handles and values in a limited number, according to the index information.
// It returns data and the next startVals until it doesn't have data, then returns data is nil and
// the next startVals is the values which can't get data. If startVals = nil and limit = -1,
// it returns the index data of the whole.
func ScanIndexData(txn kv.Transaction, kvIndex kv.Index, startVals []interface{}, limit int64) (
[]*RecordData, []interface{}, error) {
it, _, err := kvIndex.Seek(txn, startVals)
if err != nil {
return nil, nil, errors.Trace(err)
}
defer it.Close()
var idxRows []*RecordData
var curVals []interface{}
for limit != 0 {
val, h, err1 := it.Next()
if terror.ErrorEqual(err1, io.EOF) {
return idxRows, nextIndexVals(curVals), nil
} else if err1 != nil {
return nil, nil, errors.Trace(err1)
}
idxRows = append(idxRows, &RecordData{Handle: h, Values: val})
limit--
curVals = val
}
nextVals, _, err := it.Next()
if terror.ErrorEqual(err, io.EOF) {
return idxRows, nextIndexVals(curVals), nil
} else if err != nil {
return nil, nil, errors.Trace(err)
}
return idxRows, nextVals, nil
}
// GetIndexRecordsCount returns the total number of the index records from startVals.
// If startVals = nil, returns the total number of the index records.
func GetIndexRecordsCount(txn kv.Transaction, kvIndex kv.Index, startVals []interface{}) (int64, error) {
it, _, err := kvIndex.Seek(txn, startVals)
if err != nil {
return 0, errors.Trace(err)
}
defer it.Close()
var cnt int64
for {
_, _, err := it.Next()
if terror.ErrorEqual(err, io.EOF) {
break
} else if err != nil {
return 0, errors.Trace(err)
}
cnt++
}
return cnt, nil
}