func (c *index) Exist(rm kv.RetrieverMutator, indexedValues []types.Datum, h int64) (bool, int64, error) {
key, distinct, err := c.GenIndexKey(indexedValues, h)
if err != nil {
return false, 0, errors.Trace(err)
}
value, err := rm.Get(key)
if kv.IsErrNotFound(err) {
return false, 0, nil
}
if err != nil {
return false, 0, errors.Trace(err)
}
// For distinct index, the value of key is handle.
if distinct {
handle, err := decodeHandle(value)
if err != nil {
return false, 0, errors.Trace(err)
}
if handle != h {
return true, handle, errors.Trace(kv.ErrKeyExists)
}
return true, handle, nil
}
return true, h, nil
}
// Create creates a new entry in the kvIndex data.
// If the index is unique and there is an existing entry with the same key, Create will return ErrKeyExists.
func (c *index) Create(rm kv.RetrieverMutator, indexedValues []types.Datum, h int64) error {
key, distinct, err := c.GenIndexKey(indexedValues, h)
if err != nil {
return errors.Trace(err)
}
if !distinct {
// TODO: reconsider value
err = rm.Set(key, []byte("timestamp?"))
return errors.Trace(err)
}
_, err = rm.Get(key)
if kv.IsErrNotFound(err) {
err = rm.Set(key, encodeHandle(h))
return errors.Trace(err)
}
return errors.Trace(kv.ErrKeyExists)
}
// Create creates a new entry in the kvIndex data.
// If the index is unique and there is an existing entry with the same key,
// Create will return the existing entry's handle as the first return value, ErrKeyExists as the second return value.
func (c *index) Create(rm kv.RetrieverMutator, indexedValues []types.Datum, h int64) (int64, error) {
key, distinct, err := c.GenIndexKey(indexedValues, h)
if err != nil {
return 0, errors.Trace(err)
}
if !distinct {
// non-unique index doesn't need store value, write a '0' to reduce space
err = rm.Set(key, []byte{'0'})
return 0, errors.Trace(err)
}
value, err := rm.Get(key)
if kv.IsErrNotFound(err) {
err = rm.Set(key, encodeHandle(h))
return 0, errors.Trace(err)
}
handle, err := decodeHandle(value)
if err != nil {
return 0, errors.Trace(err)
}
return handle, errors.Trace(kv.ErrKeyExists)
}