Create a MongoCompoundKeyShardedPartitioner.

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Was: MongoShardedPartitioner does not support Compound shard keys

MongoShardedPartitioner does not seem to support compound shard keys
I am trying to use MongoShardedPartitioner with my SPARK job, to read data from MONGO but unable to make it work.

My Compound Shard Key ==>
"key" :

{ "shardkey_type" : 1, "shardkey_value" : 1 }

,

Now what should i pass to shardKey partitionerOptions in ReadConfig?
Looking at the source code's generatePartitions method, it expects a shardKey and use it to generate a boundary query but in case of compound query am unable to make it work and believe (based on the source code) it doesn't support COMPOUND SHARD KEYs ==>

private[partitioner] def generatePartitions(chunks: Seq[BsonDocument], shardKey: String, shardsMap: Map[String, Seq[String]]): Array[MongoPartition] = {
chunks.zipWithIndex.map(

{ case (chunk: BsonDocument, i: Int) => MongoPartition( i, PartitionerHelper.createBoundaryQuery( shardKey, chunk.getDocument("min").get(shardKey), chunk.getDocument("max").get(shardKey) ), shardsMap.getOrElse(chunk.getString("shard").getValue, Nil) ) }

).toArray
}

def createBoundaryQuery(key: String, lower: BsonValue, upper: BsonValue): BsonDocument =
new BsonDocument(key, new BsonDocument("$gte", lower).append("$lt", upper))

Please advise and help.