assert docID == it.docBase;
// no need to decompress, just copy data
indexWriter.writeIndex(it.chunkDocs, fieldsStream.getFilePointer());
writeHeader(this.docBase, it.chunkDocs, it.numStoredFields, it.lengths);
it.copyCompressedData(fieldsStream);
this.docBase += it.chunkDocs;
docID = nextLiveDoc(it.docBase + it.chunkDocs, liveDocs, maxDoc);
docCount += it.chunkDocs;
mergeState.checkAbort.work(300 * it.chunkDocs);
} else {