overwrite panic during recovery

Panic message: attempt to overwrite compacted entries in xx.

This panic should be elided during parallel recovery. Consider this case:

file A: [index=1][index=2] file B: [index=3][index=2][index=3]

It would raise a false panic if we recovery file B alone and try to merge it with file A afterwards.

Workaround:

Disable parallel recovery by setting recovery_threads to 1
Repair the log files with this script:

fn filter_append(id, first, count, rewrite_count, queue, ifirst, ilast) {
  if id == rid && first + count - 1 >= ifirst {
    return 2;  // discard existing
  }
  0
}
fn filter_compact(id, first, count, rewrite_count, queue, compact_to) {
  0
}
fn filter_clean(id, first, count, rewrite_count, queue) {
  0
}

tikv / raft-engine

overwrite panic during recovery #250