pisa support database sharding strategy and distributed transactions

[lzbjut]

Feature Request

Is your feature request related to a problem? Please describe:

when mysql data amount and throughout grows，the sharding strategy is not limited in one database ,in some key scene ,the data is distributed in several databases and tables

Describe the feature you'd like:

databases and tables sharding strategy support ,with usual algorithms .such as :
hashcodes
crc32
surplus
substring

support distributed transactions

Describe alternatives you've considered:

support databases and table sharding strategy configured in traffic strategy configuration
support Local Transaction,2PC Transaction and BASE Transaction

Teachability, Documentation, Adoption, Migration Strategy:

multiple shardng database ,tables routing
cross database transaction

[mlycore]

This is a very important feature request. That's from the real business scenes.

[mlycore]

I'd like to take this issue into discussion in the following community calls. Thanks @lzbjut