I'm aware that the Mongo "ObjectId" has the method "getTimestamp()" , which works like
ObjectId("507f191e810c19729de860ea").getTimestamp()
And also I'm aware that it can be sorted based on built-in 'timestamp'
db.collection.find().sort({'timestamp': -1})
I know I can create a new field "created_time" in each document by converting ObjectId to created_time, then query based on this new field.
I've also read this post which converts the date range to ObjectId and then directly compare the ObjectId, but this method I'm worried about the other bytes which is not for time but for machine and process.
My question is, is there a way to directly query documents in a date range using Mongo built-in 'timestamp'? without extra field or extra effort.
something like below (but I tried below command and not working), which can directly query Mongo using its built-in timestamp.
db.collection.find({'timestamp':{$gt: new Date(ISODate("2015-08-14T14:00:00Z"))}})
Related
I have a collection list such:
{username: 'somename',
friendId: '57d725d6b8b144044602bf74' <-- This a reference objectId to another doc
}
When I query docs in my collection with criteria {friendId : '57d725d6b8b144044602bf74'} I get no results back .
Any other field query works fine.
I tried to convert the value to ObjectId('57d725d6b8b144044602bf74') even though the value is just a string, still no go.
Why am I failing to search for by that type of string ?
you are trying to achieve 'self-join' in mongoDB and you seems to rely on the _id field generated by mongodb.
i would suggest you to supply custom _ID fields to the document.
eg:
{_id:"alex", name:"alex", friendID:""}
{_id"john", name"john", friendID:"alex"}
and then you can execute your queries with ease on friendID field. Give it a shot and see if this make sense for your requirement.
I am trying to query dates in mongodb.
The dates are stored as ISODate("2015-10-08T05:48:55.778+0000").
Now how should i do query like $gte or $lte.
I have been using Play plugin for reactive mongo
To query from the mongo shell, I would need to query with=>
{"endDateTime":{"$eq": new Date("2017-10-08T05:48:55.778+0000")}
OR,
{"endDateTime":{"$eq": ISODate("2017-10-08T05:48:55.778+0000")}
So, what should I do to query it using play reactive mongo. I have been using JodaTime. I am generating the Json Object of the query, and feeding to the find() api straightaway.
*Yes there a lot suggestion in SO, about the topic, but none of them seem to help me in this case. I could give more info if needed.
Update Answer:
Seems like I had some confusion, when converting the dates.
When I tried converting the String Date to Joda DateTime , the result when I print it in console, it would be shown as timestamp,but when I sent it to reactive mongo find it would convert to some form of string date "2015-10-08T05:48:55.778+0000".
So, I had to retrieve the millisecond conversion and send it to the respective api, and mongo would process without any issues.
I need monitor the time of the records been created, for further query and modify.
first thing flashed in my mind is give the document a "createDateTime" field, with the default value of "new Date()", but Mongodb said the document _id has a timestamp embedded with, and the id was generated when the document was created, so it sounds dummy to add a new field for that.
for too many times, I've seen people set a "createDateTime" for their data, and I don't know if they know about the details of mongodb's _id.
I want know should I use the _id as a "createDateTime" field? what is the best practice?
and the pros and cons.
thanks for any tips.
I'd actually say it depends on how you want to use the date.
For example, it's not actionable using the aggregation framework Date operators.
This will fail for example:
db.test.aggregate( { $group : { _id: { $year: "$_id" } } })
The following error occurs:
"errmsg" : "exception: can't convert from BSON type OID to Date"
(The date cannot be extracted from the ObjectId.)
So, operations that are normally simple date operations become much more complex if you wanted to do any sort of date math in an aggregation. It would be far easier to have a createDateTime stamp. Counting the number of documents created in a particular year and month would be simple using aggregation with a distinct createdDateTime field.
You can sort on an ObjectId, to some degree. The remaining 8 bytes of the ObjectId aren't sortable in a meaningful way. Most MongoDB drivers default to creating the ObjectId within the driver and not on the database. So, if you've got multiple clients (like web servers for example) creating new documents (and new ObjectIds), the time stamps will only be as accurate as the various servers.
Also, depending the precision you'd need, an ISODate value is stored using 8 bytes, rather than the 4 used in an ObjectId.
Yes, you should. There is no reason not to do, besides the human readability while directly looking into the database. See also here and here.
If you want to use the aggregation framework to group by the date within _id, this is not possible yet as WiredPrairie correctly said. There is an open jira ticket for that, you might watch. But of course you can do this with Map-Reduce and ObjectID.getTimestamp(). An example for that can be found here.
I have activities that I should add to mongodb, activities have, dates and times, I should sort them, What I want, is not to have another field for timestamp and index that field also, I don't want the time when the document is created, I want to embed that activitie's timestamp to mongoid, I searched and tried this one but did not work,
"_id" => new MongoId($stamp)
Is there a chance, that I can embed future timestamp to mongoid ? thank you :)
It is possible, but not directly through the driver. I have written an example at Create MongoDB ObjectID from date in the past using PHP driver that shows you how to do this.
I am trying to use mongodb's ObjectID to do a range query on the insertion time of a given collection. I can't really find any documentation that this is possible, except for this blog entry: http://mongotips.com/b/a-few-objectid-tricks/ .
I want to fetch all documents created after a given timestamp. Using the nodejs driver, this is what I have:
var timeId = ObjectId.createFromTime(timestamp);
var query = {
localUser: userId,
_id: {$gte: timeId}
};
var cursor = collection.find(query).sort({_id: 1});
I always get the same amount of records (19 in a collection of 27), independent of the timestamp. I noticed that createFromTime only fills the bytes in the objectid related to time, the other ones are left at 0 (like this: 4f6198be0000000000000000).
The reason that I try to use an ObjectID for this, is that I need the timestamp when inserting the document on the mongodb server, not when passing the document to the mongodb driver in node.
Anyone knows how to make this work, or has another idea how to generate and query insertion times that were generated on the mongodb server?
Not sure about nodejs driver in ruby, you can simply apply range queries like this.
jan_id = BSON::ObjectId.from_time(Time.utc(2012, 1, 1))
feb_id = BSON::ObjectId.from_time(Time.utc(2012, 2, 1))
#users.find({'_id' => {'$gte' => jan_id, '$lt' => feb_id}})
make sure
var timeId = ObjectId.createFromTime(timestamp) is creating an ObjectId.
Also try query without localuser