DOYUNG YOON created S2GRAPH-213:
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Summary: Abstract Query/Mutation from Storage.
Key: S2GRAPH-213
URL: https://issues.apache.org/jira/browse/S2GRAPH-213
Project: S2Graph
Issue Type: Improvement
Components: s2core
Reporter: DOYUNG YOON
Currently, Storage has many components to implement, and most of them are very
specific to HBase storage backend(ex: WriteWriteConflictResolver).
Even though it is possible to add new storage backend using current
abstraction, Storage, there are too many works which is not common to all
storage backend
I am suggesting following simple interface which is all common for any storage
backend to be integrated with.
{noformat}
trait Fetcher {
def init(config: Config)(implicit ec: ExecutionContext): Future[Fetcher] =
Future.successful(this)
def fetches(queryRequests: Seq[QueryRequest],
prevStepEdges: Map[VertexId, Seq[EdgeWithScore]])(implicit ec:
ExecutionContext): Future[Seq[StepResult]]
def close(): Unit = {}
}
{noformat}
{noformat}
trait Mutator {
def mutateVertex(zkQuorum: String, vertex: S2VertexLike, withWait:
Boolean)(implicit ec: ExecutionContext): Future[MutateResponse]
def mutateStrongEdges(zkQuorum: String, _edges: Seq[S2EdgeLike], withWait:
Boolean)(implicit ec: ExecutionContext): Future[Seq[Boolean]]
def mutateWeakEdges(zkQuorum: String, _edges: Seq[S2EdgeLike], withWait:
Boolean)(implicit ec: ExecutionContext): Future[Seq[(Int, Boolean)]]
def incrementCounts(zkQuorum: String, edges: Seq[S2EdgeLike], withWait:
Boolean)(implicit ec: ExecutionContext): Future[Seq[MutateResponse]]
def updateDegree(zkQuorum: String, edge: S2EdgeLike, degreeVal: Long =
0)(implicit ec: ExecutionContext): Future[MutateResponse]
def deleteAllFetchedEdgesAsyncOld(stepInnerResult: StepResult,
requestTs: Long,
retryNum: Int)(implicit ec: ExecutionContext): Future[Boolean]
}
{noformat}
By abstracting query/mutation as above interface, it is possible to implement
JDBCFetcher and JDBCMutator that read/write vertex and edge into any JDBC
enabled storage only implementing above interfaces.
One thing to discuss is how we are going to maintain the information about what
ServiceColumn/Label use which storage implementation.
The naive solution would be store configuration for storage backend into
ServiceColumn/Label's options field, which accepts JSON, and make S2Graph
instance to maintain the mapping of what ServiceColumn/Label use which storage
implementation.
I think above abstraction make it possible to use different implementation per
each ServiceColumn/Label, and more importantly, the user can provide their own
implementation.
For example, storing `User` vertex into Postgresql and `Friends` edges into
HBase can be possible. Also, users who do not want to use S2Graph for vertex,
do not need to store vertex at all, but by implementing `Fetcher` interface
they can still traverse vertex as they are stored in S2Graph.
Come up with this suggestion while working on S2GRAPH-206, since model serving
requires different implementation for `Fetcher` per model.
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