Add support for range deletion when user timestamps are not persisted

[jowlyzhang]

For the user defined timestamps in memtable only feature, some special handling for range deletion blocks are needed since both the key (start_key) and the value (end_key) of a range tombstone can contain user-defined timestamps. Handling for the key is taken care of in the same way as the other data blocks in the block based table. This PR adds the special handling needed for the value (end_key) part. This includes:

1. On the write path, when L0 SST files are first created from flush, user-defined timestamps are removed from an end key of a range tombstone. There are places where it's logically removed (replaced with a min timestamp) because there is still logic with the running comparator that expects a user key that contains timestamp. And in the block based builder, it is eventually physically removed before persisted in a block.

2. On the read path, when range deletion block is being read, we artificially pad a min timestamp to the end key of a range tombstone in BlockBasedTableReader.

3. For file boundary FileMetaData.largest, we artificially pad a max timestamp to it if it contains a range deletion sentinel. Anytime when range deletion end_key is used to update file boundaries, it's using max timestamp instead of the range tombstone's actual timestamp to mark it as an exclusive end.

   rocksdb/db/dbformat.h

   Lines 923 to 935 in d69628e

   	InternalKey SerializeEndKey() const {
   	if (!ts_.empty()) {
   	static constexpr char kTsMax[] = "\xff\xff\xff\xff\xff\xff\xff\xff\xff";
   	if (ts_.size() <= strlen(kTsMax)) {
   	return InternalKey(end_key_, kMaxSequenceNumber, kTypeRangeDeletion,
   	Slice(kTsMax, ts_.size()));
   	} else {
   	return InternalKey(end_key_, kMaxSequenceNumber, kTypeRangeDeletion,
   	std::string(ts_.size(), '\xff'));
   	}
   	}
   	return InternalKey(end_key_, kMaxSequenceNumber, kTypeRangeDeletion);
   	}

   
   This max timestamp is removed when in memory FileMetaData.largest is persisted into Manifest, we pad it back when it's read from Manifest while handling related VersionEdit in VersionEditHandler.

Test Plan:
Added unit test and enabled this feature combination's stress test.

[facebook-github-bot]

@jowlyzhang has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[cbi42]

LGTM! Left some non-blocking comments.

[cbi42]

I suggest run stress test with a high delrangepercent and/or different range_deletion_width for test plan.

[facebook-github-bot]

@jowlyzhang has updated the pull request. You must reimport the pull request before landing.

[facebook-github-bot]

@jowlyzhang has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[facebook-github-bot]

@jowlyzhang merged this pull request in 071a146.