MongoDB: Usage of lookup() function throws an exception ------------------------------------------------------- Key: TEIID-2990 URL: https://issues.jboss.org/browse/TEIID-2990 Project: Teiid Issue Type: Bug Security Level: Public(Everyone can see) Components: Misc. Connectors Affects Versions: 8.4.1 Reporter: Filip Elias Assignee: Ramesh Reddy Labels: Beta1 Fix For: 8.7.1, 8.8 Attachments: server.log Exception[1] is thrown when function lookup() is used in SQL query. Mongo translator doesn't support selection of constants only, which causes the exception(select 1, select 'hi' from smalla). {code} [1] 3:59:20,997 ERROR [org.teiid.CONNECTOR] (Worker5_QueryProcessorQueue6) Connector worker process failed for atomic-request=Ef2Z7E0246by.1.5.3: com.mongodb.CommandFailureException: { "serverUsed" : "localhost/127.0.0.1:27017" , "errmsg" : "exception: $projection requires at least one output field" , "code" : 16403 , "ok" : 0.0} at com.mongodb.CommandResult.getException(CommandResult.java:71) {code} Server log is in the attachment. Sample query: {code} SELECT BQT1.SmallA.IntKey FROM BQT1.SmallA, BQT1.SmallB WHERE BQT1.SmallA.IntKey= lookup('BQT1.SmallB', 'IntKey', 'StringKey', BQT1.SmallA.StringKey) ORDER BY IntKey {code} Generated mongo commands: {code} { aggregate: "smalla", pipeline: [ { $project: { _m0: "$INTKEY", _m1: "$STRINGKEY" } } ] } {code} and {code} { aggregate: "smallb", pipeline: [ { $project: {} } ] } {code}