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#mongodb logs for Thursday the 4th of February, 2016
[01:30:21] <Boomtime> it sounds like what you're asking about is a mongoose 'feature' - presumably mongoose blindly ensures indexes that you define whenever it starts up or something like that
[01:31:01] <Boomtime> if that's true, then that would be a disaster waiting to happen on a production system since an index build (in the foreground at least) will block access to the affected collection while the index is built
[01:31:50] <Boomtime> building an index in the background will maintain access, but it's hardly cheap, it can have a serious impact still
[01:34:35] <bros> so, having 12 microservices ensuring indexes every time they restart, even in the background
[03:38:05] <Lope> I'm developing a mongoDB application, and it would greatly speed up my dev time if I can take a snapshot my DB, then run some crazy code on it, change the code, then revert the DB back to the snapshot, and do it again?
[03:40:35] <Lonesoldier728> Member.find({}).where({sent: false, group: "events"}).exec(function (err, members) {
[03:40:38] <Lonesoldier728> Hey anyone know why I get a type error path where has to be a string for this query...
[07:36:02] <msn> is it possible to exclude a databse from a replication set member which is hidden and has 0 priority
[11:00:05] <okdamn> Hi why does if i want to insert a date in a Date() field mongo insert that with timezone ?
[11:45:31] <shortCircuit__> okdamn you could do object { date, month, year} or set the type to string
[13:04:27] <sandstrom> Are there any issues/risks with using `mongoexport` on a running instance (a read-replica instance)?
[13:29:20] <gabrielsch> can I query with two different orders? example: order by newest products and availables first
[14:06:59] <CustosLimen> https://docs.mongodb.org/v3.0/reference/configuration-options/#sharding.clusterRole
[14:15:03] <Ange7> i try to aggregate data with in key a date column : 'date' => ['$dateToString' => [ 'format' => '%Y-%m-%d', 'date' => '$date' ] but my «date» is NumberLong (timestamp) so i have error that $date is not a date..
[14:37:13] <Ange7> aggregate.... : ['$group' => [ '_id' => ['date' => ['$dateToString' => [ 'format' => '%Y-%m-%d', 'date' => new MongoDate('$date') ] ] ], 'count' => [ '$sum' => 1] ] ],
[15:03:34] <Ange7> I'm using PHP to create my Pipeline. $dateToString => [ 'date' => new MongoDate( HERE_MY_DATE_COLUMN) ]
[15:16:25] <Ange7> is it possible to declare one temporary variable in $project for example ? $project : { 'myTemporaryField' : { '$type': 'timestamp', 'value': $date } } and in my pipeline i using $myTemporaryField ?
[16:13:01] <GothAlice> Ange7: When in doubt, try it out! > db.foo.aggregate([{$project: {newField: {$literal: 27}}}]) → { "_id" : ObjectId("56b376ed7b48fcbccd26afe9"), "newField" : 27 }
[16:13:19] <GothAlice> > db.foo.aggregate([{$project: {newField: {$literal: new Date()}}}]) → { "_id" : ObjectId("56b376ed7b48fcbccd26afe9"), "newField" : ISODate("2016-02-04T16:07:02.655Z") }
[16:17:02] <Ange7> GothAlice: cause i need to use one date column in LongNumber to $dateToString who accepte only Date Object
[16:18:26] <Ange7> db.foo.aggregate([{$project: {newField: {$literal: new Date( $myColumnLongNumber )}}}])
[16:20:26] <GothAlice> In the long term, it might be a good idea to fix your data so your dates are actually dates and not numbers – everywhere. A UNIX timestamp is not generally a useful thing, except for some very, very specific situations.
[16:29:31] <zylo4747> anyone know how to persistently set the blockdev in centos7? i added it to rc.local and it's not applying after reboot. if i run blockdev --setra 256 /my/device it works just fine at the command line
[16:33:37] <GothAlice> Ange7: I'm very sorry, but I'm not fully understanding what you are trying to do. And as I mentioned, I can't help with PHP; it's a language I avoid for several thousand reasons.
[16:35:08] <Ange7> db.myCollection.aggregate([{$project: { newField: "$date" }}]); → { "_id" : ObjectId("568fe38c33381222108b4567"), "newField" : NumberLong(1452270476) }
[16:35:54] <Ange7> db.myCollection..aggregate([{$project: { newField: Date("$date") }}]); → 2016-02-04T17:29:13.123+0100 E QUERY [thread1] Error: command failed: {
[16:35:55] <GothAlice> Except now that it's a number, you literally can't _do_ anything with it: https://docs.mongodb.org/manual/meta/aggregation-quick-reference/#date-expressions
[16:36:14] <GothAlice> Ange7: Why are you wrapping Date() around the second one when you weren't in the first?
[16:37:01] <GothAlice> Date() would be executed at the level of your code, in your programming language, not in MongoDB, so does your programming language know what Date("$date") means? (Nope.)
[16:38:22] <GothAlice> Because numbers aren't dates. (Dates have timezones, UNIX timestamps have no way of storing that information, and no expression is provided in MongoDB to convert.)
[16:39:08] <GothAlice> cheeser: Turning a real date into a ts is… accomplishable using the date projections and some math. The reverse is, from what I can tell, impossible.
[16:39:27] <Ange7> GothAlice: Ok but i want aggregate data by date string (id: 2016-02-04) so i need to transform my longNumber to dateToString
[16:40:19] <Ange7> why i can't simply modify longNumber type to Timestamp type with one update for example ?
[16:41:01] <GothAlice> cheeser: That's happening at the client level, but the number is in the documents.
[16:41:47] <GothAlice> Ange7: If instead of using timestamps you were using real dates, what you ask would be utterly trivial. {$project: {myGroupField: {$dateToString: {format: "%Y-%m-%d", date: "$myDateField"}}}}
[16:42:09] <GothAlice> (Or just $group with {$dateToString: {format: "%Y-%m-%d", date: "$myDateField"}} as the _id.)
[16:43:10] <GothAlice> Well, the terminology here is confusing. UNIX timestamps are numbers. You can't convert numbers to real Date objects.
[16:44:08] <GothAlice> Ange7: When storing dates, store them as dates, not as numbers. Then, suddenly, everything works.
[16:44:56] <GothAlice> This is why understanding the tools and designing carefully before starting is important. :(
[16:48:57] <GothAlice> Ange7: https://docs.mongodb.org/manual/meta/aggregation-quick-reference/#date-expressions < all of these work only on Date, not timestamps.
[16:51:51] <tantamount> When aggregating, is it possible to do either of the following: (A) number each document in sequential order, and (B) assign specific values to the first three documents under certain conditions?
[16:53:22] <tantamount> @GothAlice, I believe both A and B require being able to identify the numerical index of the document (after sorting, of course)
[16:54:51] <tantamount> I haven't come across any documentation that suggests a document is ever aware of its position in the collection of documents output at any stage of the pipeline
[16:55:08] <GothAlice> One could fake it using an array that is $push'd to, getting the $size of the array to indicate position.
[16:55:59] <tantamount> How do I only push one thing to the first one, two to the second, and so on?
[16:56:03] <GothAlice> $group on 1, $push each whole document into an array while projecting into the document the current $size of the array.
[16:57:14] <GothAlice> Combines all records into one, giving you the opportunity to $sum, etc. them. We'd $push them to an array because we actually do want all the records, which you can then $unwind to turn back into separate records. Be careful of the 16MB document size limit when doing this, though. ;P
[16:58:24] <tantamount> At this stage in the pipeline I'd never have more than a few hundred documents at the absolute max, each of which only has two fields. I'm pretty safe with that limit
[17:00:58] <StephenLynx> if something seems to be harder to be done on the db than on application code, its better to do it on application code.
[17:02:00] <GothAlice> Turns out the order of operator evaluation makes that hack even more hacky than it should be.
[17:03:04] <StephenLynx> the part of the numerical value for each one you just have to run a for and assign the current iterator value to each document
[17:03:24] <StephenLynx> while you are at that, do the other thing of assigning a value to the first three
[20:44:20] <Frenchiie> anyone know how to make reference to new Date()? https://docs.mongodb.org/manual/reference/bson-types/#date
[20:47:30] <GothAlice> Then use datetime() objects to store dates. (Pro tip: also install pytz and make sure you apply a timezone to your dates.) expireAfterSeconds is simply a number of seconds.
[20:48:52] <Frenchiie> is expireAfterSeconds suppose to be a string? because its in a dict format {}
[20:49:11] <Frenchiie> the tutorial shows db.log_events.createIndex( { "expireAt": 1 }, { expireAfterSeconds: 0 } )
[20:49:22] <GothAlice> Sorry, I'm not following. The second argument to createIndex are the options for the index.
[20:52:54] <GothAlice> The examples in the documentation are for the Mongo shell, thus JavaScript, where quotes around object literal attribute names isn't required.
[20:54:00] <GothAlice> Using the correct documentation for the Python driver indicates that Python uses standard keyword arguments to collection.create_index() instead of an object literal: http://api.mongodb.org/python/current/api/pymongo/collection.html#pymongo.collection.Collection.create_index