Current commit introduces distributed SQL in picodata (we use
'sbroad' library). Now it is possible to execute cluster-wide
SQL with 'pico.sql([[query]], {params})' lua method.

Current limitations:
1. DDL is still not implemented in picodata, so space sharding
   is mocked by '_pico_space' space (we'll remove it later).
2. We still have duplicating symbols of the Tarantool module in
   sbroad and in picodata rlibs.
3. We need to reuse piocdata's sharding functions and handle the
   case when different spaces in the query have different sharding
   functions.

Co-authored-by: Georgy Moshkin <gmoshkin@picodata.io>

Yaroslav Dynnikov authored 1 year ago and Yaroslav Dynnikov committed 1 year ago

Adopted styleguide is "actual == expected", not vice versa.

NOTE: there's still a bug, because we set each new replicaset's weight
to 1 (even ones which don't satisfy replication factor)
before the bucket distribution is bootstrapped. But there must be at
least one replicaset with non zero weight in order for vshard.*.cfg to
work.

A potential solution would be to only configure vshard once a replicaset
is filled up.

Georgy Moshkin authored 2 years ago and Yaroslav Dynnikov committed 2 years ago

Tarantool synchronous replication is broken in such a way, that local
& asynchronous transactions get rolled back upon synchronous
transaction rollback. This is critical for us, because we use local
spaces for the raft log, which should be orthogonal to synchronous
business spaces, but is not due to this behavior. Until it is fixed, we
will not use synchronous replication.

See https://github.com/tarantool/tarantool/issues/7903