func (s *session) flushMemdb(rec *sessionRecord, mdb *memdb.DB, maxLevel int) (int, error) {
// Create sorted table.
iter := mdb.NewIterator(nil)
defer iter.Release()
t, n, err := s.tops.createFrom(iter)
if err != nil {
return 0, err
}
// Pick level other than zero can cause compaction issue with large
// bulk insert and delete on strictly incrementing key-space. The
// problem is that the small deletion markers trapped at lower level,
// while key/value entries keep growing at higher level. Since the
// key-space is strictly incrementing it will not overlaps with
// higher level, thus maximum possible level is always picked, while
// overlapping deletion marker pushed into lower level.
// See: https://github.com/pingcap/goleveldb/issues/127.
flushLevel := s.pickMemdbLevel(t.imin.ukey(), t.imax.ukey(), maxLevel)
rec.addTableFile(flushLevel, t)
s.logf("memdb@flush created L%d@%d N·%d S·%s %q:%q", flushLevel, t.fd.Num, n, shortenb(int(t.size)), t.imin, t.imax)
return flushLevel, nil
}
func isMemOverlaps(icmp *iComparer, mem *memdb.DB, min, max []byte) bool {
iter := mem.NewIterator(nil)
defer iter.Release()
return (max == nil || (iter.First() && icmp.uCompare(max, internalKey(iter.Key()).ukey()) >= 0)) &&
(min == nil || (iter.Last() && icmp.uCompare(min, internalKey(iter.Key()).ukey()) <= 0))
}