Info

I have created a collection having a compound index, as : db.ConnectedobjectValue.getIndexes()[{ "v" : 2, "key" : { "entryDate" : -1, "idParameter" : -1, "idConnectedobject" : -1 }, "name" : "entryDate_-1_idParameter_-1_idConnectedobject_-1", "ns" : "DB.ConnectedobjectValue", "background" : true }] Then I tried to perform a simple find using this compound index : db.ConnectedobjectValue.find({}).hint({ entryDate: -1, idConnectedobject: -1, idParameter: -1 }) And I got the following error : Error: error: {Error: error: { "ok" : 0, "errmsg" : "error processing query: ns=ELIOT.ConnectedobjectValueTree: $and\nSort: {}\nProj: {}\n planner returned error: bad hint", "code" : 2, "codeName" : "BadValue"} I have found that changing the order of the names in my find request make it to work : db.ConnectedobjectValue.find({}).hint({ entryDate: -1, idParameter: -1, idConnectedobject: -1 }) Which is non sense considering that json do not guarantee keys order.

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daniel.hatcher commented on Mon, 29 Jul 2019 19:08:56 +0000: To follow up orelsanpls, you could have also resolved this issue by using a Map rather than an Object. As you mentioned, JSON does not preserve order. NODE-578 provided the option to use a Map instead so that the ordering is consistent every time. As this is a known fix for the issue, I'm going to close this ticket. eric.sedor commented on Wed, 10 Jul 2019 21:21:07 +0000: Thanks orelsanpls, we are going to attempt a reproduction of this and will update this ticket if we have additional questions. orelsanpls commented on Wed, 10 Jul 2019 09:25:43 +0000: I'm using : mongodb v4.0.3 node.js v8.9.4 mongoose@5.6.3 which use the npm packages : - "mongodb": "3.2.7" - "mongodb-core": "3.2.7" orelsanpls commented on Wed, 10 Jul 2019 09:17:09 +0000: Hello, thank you for replying to this ticket. Yes { idConnectedobject: -1, idParameter: -1, entryDate: -1 } resulted in bad hint. Now that I've restarted my program, I do not reproduce, so I strongly guess that the keys that was given for the hint got transmitted to mongodb in the wrong order. Mongoose node.js package is relying on mongodb-native package which just pass the hint option to mongodb (here is what I've found on theirs githubs) : https://github.com/mongodb/node-mongodb-native/blob/master/lib/utils.js Line 165 /** * @ignore */ var normalizeHintField = function normalizeHintField(hint) { var finalHint = null; if (typeof hint === 'string') { finalHint = hint; } else if (Array.isArray(hint)) { finalHint = {}; hint.forEach(function(param) { finalHint[param] = 1; }); } else if (hint != null && typeof hint === 'object') { finalHint = {}; for (var name in hint) { finalHint[name] = hint[name]; } } return finalHint; }; About the `for ... in` implementation, there are this stack overflow answer https://stackoverflow.com/questions/280713/elements-order-in-a-for-in-loop The behavior of `for ... in` could be specific to the node.js version PS: I didn't knew I could pass the name of the index, thank you for the input, I do use this method now and it works well! eric.sedor commented on Tue, 9 Jul 2019 23:46:40 +0000: Hi orelsanpls, To hint to the index { "entryDate" : -1, "idParameter" : -1, "idConnectedobject" : -1 } you should be able to pass { "entryDate" : -1, "idParameter" : -1, "idConnectedobject" : -1 } (the key specification) or "entryDate_-1_idParameter_-1_idConnectedobject_-1", the index name. So your original description sounds like what should be expected. For your follow-up comment can you please clarify: Are you saying that { idConnectedobject: -1, idParameter: -1, entryDate: -1 } results in a bad hint even though an index exists on { idConnectedobject: -1, idParameter: -1, entryDate: -1 }? orelsanpls commented on Tue, 9 Jul 2019 10:01:21 +0000: Actually I saw that the compound index key order is important as specified in the documentation https://docs.mongodb.com/manual/core/index-compound/ I think it's more of a node.js issue. Because in node.js the order of the keys are not guaranteed which leads to possible issues. My program is in `node.js` using `npm` package `mongoose`, even providing the indexes in the correct order, I get a bad hint : stringError: 'MongoError: error processing query: ns=DB.ConnectedobjectValue limit=80Tree: $and\n idParameter $eq ObjectId(\'b00060300000000000000046\')\n entryDate $lte new Date(1562663058593)\nSort: { entryDate: -1 }\nProj: { _id: 1, entryDate: 1, idConnectedobject: 1, idParameter: 1, value: 1 }\n planner returned error: bad hint\n at Connection. (/x/node_modules/mongodb-core/lib/connection/pool.js:443:61)\n at emitTwo (events.js:126:13)\n at Connection.emit (events.js:214:7)\n at processMessage (/x/node_modules/mongodb-core/lib/connection/connection.js:364:10)\n at Socket. (/x/node_modules/mongodb-core/lib/connection/connection.js:533:15)\n at emitOne (events.js:116:13)\n at Socket.emit (events.js:211:7)\n at addChunk (_stream_readable.js:263:12)\n at readableAddChunk (_stream_readable.js:250:11)\n at Socket.Readable.push (_stream_readable.js:208:10)\n at TCP.onread (net.js:594:20)' Order I set in my code : {  idConnectedobject: -1, idParameter: -1, entryDate: -1, } The indexes list :

Steps to Reproduce