@Override
  public void updateLowestUnflushedSequenceIdInWAL(boolean onlyIfGreater) {
    long minSequenceId = pipeline.getMinSequenceId();
    if (minSequenceId != Long.MAX_VALUE) {
      byte[] encodedRegionName = getRegionServices().getRegionInfo().getEncodedNameAsBytes();
      byte[] familyName = getFamilyNameInBytes();
      WAL WAL = getRegionServices().getWAL();
      if (WAL != null) {
        WAL.updateStore(encodedRegionName, familyName, minSequenceId, onlyIfGreater);
      }
    }
  }
Push the current active memstore segment into the pipeline and create a snapshot of the tail of
current compaction pipeline Snapshot must be cleared by call to {@link #clearSnapshot}.
{@link #clearSnapshot(long)}.
@return {@link MemStoreSnapshot}
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/CompactingMemStore.java