Features:

Add command for manager user check @@metadata. For more details, see:check @@metadata
Improve performance of initializing metadata #700 . You can use old logic by setting useOldMetaInit in server.xml
New check item in Dryrun #712
Add RocksDB support for cache using FST for serializer #691. For more details, see:cache_setting (thanks @runfriends)

Bug-fixes:

Join Error when the join Key contain value null #681
Derived subquery should be optimized if it is an ER/Global JOIN #685 #701
Client get lost connection when try to load data local for a empty file #683
Close backend connection asynchronously
Charset of group_concat is not correct #679
Treat single node sharding table as no-sharding table #687 #692
Union with duplicate constant in select error #671
Union more than 3 resultSet and with function exec get Error #678
Charset set in server.xml works on backend connection #689
Hint logic fix #670 #669 #649 #696 #697 #698
Sub query logic fix when tmp results contains null #715 #716 #719 #722 #720 #724 #725 #729 #730 #731 #736 #737 #741 #742
select * from a left join b on a.col1=b.col1 where b.col1 is null" can't filter out expect line #717
load data bugs #703 #772 #774
Hang when execute DDL on dble cluster manager by ZK #732
multi-query with ddl may need sync context resolve verified #743
'reload' hang until tcp is completed, when the backend node is broken network resolve verified #739
MaxCon do not work when the concurrent number increase rapidly #745
If slow query log size larger than 64M,log file roll over failed #751
Multiple statements add view create/drop support and ErrorPacket packetId fix #746
"select id, -sum(c_decimal) [as] c2 from aly_test group by id order by c2 desc;" got "field not found:-SUM(c_decimal)" #758