// DecodeIndexKey decodes the values that are a part of the specified index
// key. ValTypes is a slice returned from makeKeyVals. The remaining bytes in the
// index key are returned which will either be an encoded column ID for the
// primary key index, the primary key suffix for non-unique secondary indexes
// or unique secondary indexes containing NULL or empty. If the given descriptor
// does not match the key, false is returned with no error.
func DecodeIndexKey(
a *DatumAlloc,
desc *TableDescriptor,
indexID IndexID,
valTypes []parser.Type,
vals []parser.Datum,
colDirs []encoding.Direction,
key []byte,
) ([]byte, bool, error) {
var decodedTableID ID
var decodedIndexID IndexID
var err error
if index, err := desc.FindIndexByID(indexID); err == nil && len(index.Interleave.Ancestors) > 0 {
for _, ancestor := range index.Interleave.Ancestors {
key, decodedTableID, decodedIndexID, err = DecodeTableIDIndexID(key)
if err != nil {
return nil, false, err
}
if decodedTableID != ancestor.TableID || decodedIndexID != ancestor.IndexID {
return nil, false, nil
}
length := int(ancestor.SharedPrefixLen)
key, err = DecodeKeyVals(a, valTypes[:length], vals[:length], colDirs[:length], key)
if err != nil {
return nil, false, err
}
valTypes, vals, colDirs = valTypes[length:], vals[length:], colDirs[length:]
// We reuse NotNullDescending as the interleave sentinel, consume it.
var ok bool
key, ok = encoding.DecodeIfNotNull(key)
if !ok {
return nil, false, nil
}
}
}
key, decodedTableID, decodedIndexID, err = DecodeTableIDIndexID(key)
if err != nil {
return nil, false, err
}
if decodedTableID != desc.ID || decodedIndexID != indexID {
return nil, false, nil
}
key, err = DecodeKeyVals(a, valTypes, vals, colDirs, key)
if err != nil {
return nil, false, err
}
// We're expecting a column family id next (a varint). If descNotNull is
// actually next, then this key is for a child table.
if _, ok := encoding.DecodeIfNotNull(key); ok {
return nil, false, nil
}
return key, true, nil
}
// DecodeIndexKeyPrefix decodes the prefix of an index key and returns the
// index id and a slice for the rest of the key.
//
// Don't use this function in the scan "hot path".
func DecodeIndexKeyPrefix(
a *DatumAlloc, desc *TableDescriptor, key []byte,
) (indexID IndexID, remaining []byte, err error) {
// TODO(dan): This whole operation is n^2 because of the interleaves
// bookkeeping. We could improve it to n with a prefix tree of components.
interleaves := append([]IndexDescriptor{desc.PrimaryIndex}, desc.Indexes...)
for component := 0; ; component++ {
var tableID ID
key, tableID, indexID, err = DecodeTableIDIndexID(key)
if err != nil {
return 0, nil, err
}
if tableID == desc.ID {
// Once desc's table id has been decoded, there can be no more
// interleaves.
break
}
for i := len(interleaves) - 1; i >= 0; i-- {
if len(interleaves[i].Interleave.Ancestors) <= component ||
interleaves[i].Interleave.Ancestors[component].TableID != tableID ||
interleaves[i].Interleave.Ancestors[component].IndexID != indexID {
// This component, and thus this interleave, doesn't match what was
// decoded, remove it.
copy(interleaves[i:], interleaves[i+1:])
interleaves = interleaves[:len(interleaves)-1]
}
}
// The decoded key doesn't many any known interleaves
if len(interleaves) == 0 {
return 0, nil, errors.Errorf("no known interleaves for key")
}
// Anything left has the same SharedPrefixLen at index `component`, so just
// use the first one.
for i := uint32(0); i < interleaves[0].Interleave.Ancestors[component].SharedPrefixLen; i++ {
l, err := encoding.PeekLength(key)
if err != nil {
return 0, nil, err
}
key = key[l:]
}
// We reuse NotNullDescending as the interleave sentinel, consume it.
var ok bool
key, ok = encoding.DecodeIfNotNull(key)
if !ok {
return 0, nil, errors.Errorf("invalid interleave key")
}
}
return indexID, key, err
}
