Hi Dennis,
I would suggest you to look at the logical plan of this query will be generating by running this sql statement 'explain plan without implementation for <Your mongo Join Query'', meanwhile you also define what is the target query you want to get for this join query against mongoDB, then you may create a rule to match the two-way Join pattern by following the example of Calcite's rule JoinPushThroughJoinRule: https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/rel/rules/JoinPushThroughJoinRule.java Hope this helps, Chunhui ________________________________ From: Dennis Knochenwefel <dennis.knochenwe...@reportix.com> Sent: Thursday, December 28, 2017 4:48:29 AM To: dev@drill.apache.org Subject: Implementing inner joins for mongo Hello Drill Dev Pros, I have found the drill mongo store and would like to extend it to push down INNER JOINs. Therefore I would like to rewrite INNER JOINs into the mongo aggregation pipeline. Here is a SQL example: SELECT * FROM `mymongo.db`.`facts` `facts` INNER JOIN `mymongo.db`.`set` `set` ON (`facts`.`group` = `set`.`group`) WHERE ((`set`.`date` = '09.05.2017') AND (`set`.`id` = '1')) Could you give me a hint how to do that? I am familiar with the aggregation pipeline of mongo, but am not sure how to implement the rewrite. I have found the push down of WHERE clauses for mongo [1] But I am still struggling to do the same for inner joins. If I implement "public class MongoPushDownInnerJoinScan extends StoragePluginOptimizerRule" then how would the constructor look like. Which equivalent of MongoGroupScan (AbstractGroupScan) [2] would I have to implement? Any help would be very much appreciated. Thank you and kind regards, Dennis [1] https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_apache_drill_blob_master_contrib_storage-2Dmongo_src_main_java_org_apache_drill_exec_store_mongo_MongoPushDownFilterForScan.java&d=DwIDaQ&c=cskdkSMqhcnjZxdQVpwTXg&r=FCGQb-L4gJ1XbsL1WU2sugDtPvzIxWFzAi5u4TTtxaI&m=AgtqT-QgqWrLpsLSl6rmMe7wlrIS_ZxLsgbN53Dw9UE&s=deXYtgUqGSZXm13dZpenqfHCMpb_H6fL6DVcSHXTMQs&e= [2] https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_apache_drill_blob_master_contrib_storage-2Dmongo_src_main_java_org_apache_drill_exec_store_mongo_MongoGroupScan.java&d=DwIDaQ&c=cskdkSMqhcnjZxdQVpwTXg&r=FCGQb-L4gJ1XbsL1WU2sugDtPvzIxWFzAi5u4TTtxaI&m=AgtqT-QgqWrLpsLSl6rmMe7wlrIS_ZxLsgbN53Dw9UE&s=zuccYRJCUAMkxZwbmaDUWZoUBdvXf8jvkQGQcS3qfZE&e= -- Dennis Knochenwefel Founder Reportix Germany
