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trying to drop the config database in mongodb 4.0.0-rc0 fails with following exception: com.mongodb.MongoCommandException: Command failed with error 40528: 'Direct writes against config.transactions cannot be performed using a transaction or on a session.' on server 127.0.0.1:27500. The full response is { "ok" : 0.0, "errmsg" : "Direct writes against config.transactions cannot be performed using a transaction or on a session.", "code" : 40528, "codeName" : "Location40528" } at com.mongodb.connection.ProtocolHelper.getCommandFailureException(ProtocolHelper.java:164) at com.mongodb.connection.InternalStreamConnection.receiveCommandMessageResponse(InternalStreamConnection.java:295) at com.mongodb.connection.InternalStreamConnection.sendAndReceive(InternalStreamConnection.java:255) at com.mongodb.connection.UsageTrackingInternalConnection.sendAndReceive(UsageTrackingInternalConnection.java:98) at com.mongodb.connection.DefaultConnectionPool$PooledConnection.sendAndReceive(DefaultConnectionPool.java:441) at com.mongodb.connection.CommandProtocolImpl.execute(CommandProtocolImpl.java:80) at com.mongodb.connection.DefaultServer$DefaultServerProtocolExecutor.execute(DefaultServer.java:189) at com.mongodb.connection.DefaultServerConnection.executeProtocol(DefaultServerConnection.java:264) at com.mongodb.connection.DefaultServerConnection.command(DefaultServerConnection.java:126) at com.mongodb.connection.DefaultServerConnection.command(DefaultServerConnection.java:118) at com.mongodb.operation.CommandOperationHelper.executeWrappedCommandProtocol(CommandOperationHelper.java:226) at com.mongodb.operation.CommandOperationHelper.executeWrappedCommandProtocol(CommandOperationHelper.java:217) at com.mongodb.operation.CommandOperationHelper.executeWrappedCommandProtocol(CommandOperationHelper.java:154) at com.mongodb.operation.CommandOperationHelper.executeWrappedCommandProtocol(CommandOperationHelper.java:147) at com.mongodb.operation.DropDatabaseOperation$1.call(DropDatabaseOperation.java:89) at com.mongodb.operation.DropDatabaseOperation$1.call(DropDatabaseOperation.java:86) at com.mongodb.operation.OperationHelper.withConnectionSource(OperationHelper.java:462) at com.mongodb.operation.OperationHelper.withConnection(OperationHelper.java:424) at com.mongodb.operation.DropDatabaseOperation.execute(DropDatabaseOperation.java:86) at com.mongodb.operation.DropDatabaseOperation.execute(DropDatabaseOperation.java:45) at com.mongodb.Mongo$3.execute(Mongo.java:837) at com.mongodb.Mongo$3.execute(Mongo.java:818) at com.mongodb.DB.dropDatabase(DB.java:227)

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kaloian.manassiev commented on Thu, 31 May 2018 14:17:47 +0000: Ah yes - this was introduced in 3.6 as part of retryable writes, so that problem would exist in 3.6 as well. ankur.srivastava, are you hitting this now because you started using the 3.6 drivers, which start sessions implicitly? tess.avitabile commented on Thu, 31 May 2018 13:51:34 +0000: Okay, great, I'm glad they have a workaround. Sure, that change sounds fine to me. The check is part of the session catalog maintenance, so I think it makes more sense for this work to be done by the Sharding team. kaloian.manassiev commented on Thu, 31 May 2018 13:45:35 +0000: I spoke with Ankur yesterday and they could live without dropping the config database because dropping the individual collections still succeeds. So as far as their use case is concerned, they can work around it. However given that they are running in standalone mode I don't think the drop should be failing. Can you just make the lsid check conditional on whether it is a replica-set or not? tess.avitabile commented on Wed, 30 May 2018 21:18:26 +0000: ankur.srivastava, is it okay to close this ticket, since we've diagnosed the issue? Can you follow up separately with kaloian.manassiev about when backup should be dropping the config database? kaloian.manassiev commented on Wed, 30 May 2018 14:08:28 +0000: While this particular error while dropping the config/admin databases seems to be something unintended, I actually prefer that it be explicitly disallowed unless the server is running in standalone mode (i.e., for some form of recovery). There is a lot of critical state stored in the config/admin databases and there should never be a reason for a user to drop them. tess.avitabile commented on Tue, 29 May 2018 15:40:32 +0000: Ah, thanks for explaining that the difference is due to the creation of the config database at startup. I spoke with jeff.yemin, and all 3.6 drivers use "implicit sessions" even when the user does not explicitly start a session: https://github.com/mongodb/specifications/blob/master/source/sessions/driver-sessions.rst#explicit-vs-implicit-sessions. So what you are seeing is expected. Please let me know if it's important to be able to drop the config database in your tests, and we can discuss possible workarounds. ankur.srivastava commented on Tue, 29 May 2018 15:00:44 +0000: I noticed that our tests are failing because config db is not created on fresh start of mongodb 3.7.9, but it is being created on mongodb 4.0.0-rc0. Even though sessions are not being used. Following is the code which does not uses sessions and throws exception on mongodb 4.0.0-rc0: import com.mongodb.MongoClient; import com.mongodb.DB; import java.util.List; import java.util.ArrayList; import java.util.Set; public class Test { public static void main(String[] args) { MongoClient client = new MongoClient("localhost", Integer.parseInt(args[0])); apply(client); } public static void apply(MongoClient mongo) { List dbNames = mongo.listDatabaseNames().into(new ArrayList()); for (String dbName : dbNames) { DB db = mongo.getDB(dbName); Set collectionNames = db.getCollectionNames(); for (String collectionName : collectionNames) { // Can't drop system collections. if (collectionName.indexOf("system.") == 0) { continue; } db.getCollection(collectionName).drop(); } if (!"admin".equals(dbName)) { System.out.println("Dropping db: " + dbName); db.dropDatabase(); System.out.println("Dropped db: " + dbName); } } } } output with 3.7.9: May 29, 2018 10:52:27 AM com.mongodb.diagnostics.logging.JULLogger log INFO: Cluster created with settings {hosts=[localhost:32000], mode=SINGLE, requiredClusterType=UNKNOWN, serverSelectionTimeout='30000 ms', maxWaitQueueSize=500} May 29, 2018 10:52:27 AM com.mongodb.diagnostics.logging.JULLogger log INFO: Cluster description not yet available. Waiting for 30000 ms before timing out May 29, 2018 10:52:27 AM com.mongodb.diagnostics.logging.JULLogger log INFO: Opened connection [connectionId{localValue:1, serverValue:3}] to localhost:32000 May 29, 2018 10:52:27 AM com.mongodb.diagnostics.logging.JULLogger log INFO: Monitor thread successfully connected to server with description ServerDescription{address=localhost:32000, type=STANDALONE, state=CONNECTED, ok=true, version=ServerVersion{versionList=[3, 7, 9]}, minWireVersion=0, maxWireVersion=7, maxDocumentSize=16777216, logicalSessionTimeoutMinutes=30, roundTripTimeNanos=1721083} May 29, 2018 10:52:27 AM com.mongodb.diagnostics.logging.JULLogger log INFO: Opened connection [connectionId{localValue:2, serverValue:4}] to localhost:32000 output with 4.0.0-rc0 May 29, 2018 10:48:21 AM com.mongodb.diagnostics.logging.JULLogger log INFO: Cluster created with settings {hosts=[localhost:31000], mode=SINGLE, requiredClusterType=UNKNOWN, serverSelectionTimeout='30000 ms', maxWaitQueueSize=500} May 29, 2018 10:48:21 AM com.mongodb.diagnostics.logging.JULLogger log INFO: Cluster description not yet available. Waiting for 30000 ms before timing out May 29, 2018 10:48:21 AM com.mongodb.diagnostics.logging.JULLogger log INFO: Opened connection [connectionId{localValue:1, serverValue:1}] to localhost:31000 May 29, 2018 10:48:21 AM com.mongodb.diagnostics.logging.JULLogger log INFO: Monitor thread successfully connected to server with description ServerDescription{address=localhost:31000, type=STANDALONE, state=CONNECTED, ok=true, version=ServerVersion{versionList=[4, 0, 0]}, minWireVersion=0, maxWireVersion=7, maxDocumentSize=16777216, logicalSessionTimeoutMinutes=30, roundTripTimeNanos=1694757} May 29, 2018 10:48:21 AM com.mongodb.diagnostics.logging.JULLogger log INFO: Opened connection [connectionId{localValue:2, serverValue:2}] to localhost:31000 Dropping db: config Exception in thread "main" com.mongodb.MongoCommandException: Command failed with error 40528: 'Direct writes against config.transactions cannot be performed using a transaction or on a session.' on server localhost:31000. The full response is { "ok" : 0.0, "errmsg" : "Direct writes against config.transactions cannot be performed using a transaction or on a session.", "code" : 40528, "codeName" : "Location40528" } at com.mongodb.connection.ProtocolHelper.getCommandFailureException(ProtocolHelper.java:164) at com.mongodb.connection.InternalStreamConnection.receiveCommandMessageResponse(InternalStreamConnection.java:295) at com.mongodb.connection.InternalStreamConnection.sendAndReceive(InternalStreamConnection.java:255) at com.mongodb.connection.UsageTrackingInternalConnection.sendAndReceive(UsageTrackingInternalConnection.java:98) at com.mongodb.connection.DefaultConnectionPool$PooledConnection.sendAndReceive(DefaultConnectionPool.java:441) at com.mongodb.connection.CommandProtocolImpl.execute(CommandProtocolImpl.java:80) at com.mongodb.connection.DefaultServer$DefaultServerProtocolExecutor.execute(DefaultServer.java:189) at com.mongodb.connection.DefaultServerConnection.executeProtocol(DefaultServerConnection.java:264) at com.mongodb.connection.DefaultServerConnection.command(DefaultServerConnection.java:126) at com.mongodb.connection.DefaultServerConnection.command(DefaultServerConnection.java:118) at com.mongodb.operation.CommandOperationHelper.executeWrappedCommandProtocol(CommandOperationHelper.java:226) at com.mongodb.operation.CommandOperationHelper.executeWrappedCommandProtocol(CommandOperationHelper.java:217) at com.mongodb.operation.CommandOperationHelper.executeWrappedCommandProtocol(CommandOperationHelper.java:154) at com.mongodb.operation.CommandOperationHelper.executeWrappedCommandProtocol(CommandOperationHelper.java:147) at com.mongodb.operation.DropDatabaseOperation$1.call(DropDatabaseOperation.java:89) at com.mongodb.operation.DropDatabaseOperation$1.call(DropDatabaseOperation.java:86) at com.mongodb.operation.OperationHelper.withConnectionSource(OperationHelper.java:462) at com.mongodb.operation.OperationHelper.withConnection(OperationHelper.java:424) at com.mongodb.operation.DropDatabaseOperation.execute(DropDatabaseOperation.java:86) at com.mongodb.operation.DropDatabaseOperation.execute(DropDatabaseOperation.java:45) at com.mongodb.Mongo$3.execute(Mongo.java:837) at com.mongodb.Mongo$3.execute(Mongo.java:818) at com.mongodb.DB.dropDatabase(DB.java:227) at Test.apply(Test.java:29) at Test.main(Test.java:10) tess.avitabile commented on Tue, 29 May 2018 13:47:21 +0000: That error message would only be generated if the dropDatabase is executed in a session. I tested that it is possible to drop the config database outside of a session in 4.0.0-rc0. Can you please provide a repro script that demonstrates the change in behavior between 3.7.9 and 4.0.0-rc0? ankur.srivastava commented on Tue, 29 May 2018 13:29:44 +0000: dropDatabase is not executed in a session. We are using java driver 3.6.3. Same code runs fine for mongodb 3.6, 3.7.9 but fails on 4.0.0-rc0. tess.avitabile commented on Fri, 25 May 2018 21:04:43 +0000: Is it possible that the dropDatabase is now executed in a session, when it was not before? Possibly due to a change in the driver? It is illegal in both 3.6 and 4.0 to drop the config database inside of a session. That is, the following example fails on both 3.6 and 4.0: (function() { const rst = ReplSetTest({nodes: 1}); rst.startSet(); rst.initiate(); const session = rst.getPrimary().getDB("test").getMongo().startSession({retryWrites: true}); const testDB = session.getDatabase("test"); const configDB = session.getDatabase("config"); assert.writeOK(testDB.c.insert({})); // Fails with "Direct writes against config.transactions cannot be performed using a // transaction or on a session." assert.commandWorked(configDB.dropDatabase()); session.endSession(); rst.stopSet(); }()); CC spencer, kaloian.manassiev

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