I think start is userkey here!

[zgcbj]

rocksdb/db/compaction/compaction.cc

Line 549 in ce0ea61

(start == nullptr) ? GetSmallestUserKey() : ExtractUserKey(*start);

ExtractUserKey(*start) will assert false!

same to ExtractUserKey(*end)

Am I right?

[tabokie]

Nice catch! Our unit tests didn't catch it because it will only be non-null when sub-compaction is involved.

The start is set here:

rocksdb/db/compaction/compaction_job.cc

Lines 542 to 550 in ce0ea61

	if (c->ShouldFormSubcompactions()) {
	{
	StopWatch sw(db_options_.clock, stats_, SUBCOMPACTION_SETUP_TIME);
	GenSubcompactionBoundaries();
	}
	assert(sizes_.size() == boundaries_.size() + 1);
	for (size_t i = 0; i <= boundaries_.size(); i++) {
	Slice* start = i == 0 ? nullptr : &boundaries_[i - 1];

And the boundaries_ is set here:

rocksdb/db/compaction/compaction_job.cc

Line 691 in ce0ea61

boundaries_.emplace_back(ExtractUserKey(ranges[i].range.limit));

You're welcome to send us a fix~