Is there a way to query mongodb in such a way that I can retrieve the time?
I often do a check where I check the time the mongodb server is running on before putting data on. I need to know the time on the db server from the point of view of a client.
I'm using the C# .NET wrapper, but if there is a query that can do this on any platform that would be nice too. How would would I get the db time?
I know there are obviously other ways to do this, by synchronizing times. But I need to use this option so there can be no tampering with the local time
db.hostInfo() returns an object where system.currentTime is the current time on the server's host.
I'm not sure what you mean by "from the point of view of a client". But, this might help:
>> db.serverStatus()
returns a big object, which includes the time. Apparently (haven't tested this), for the java driver you can get this with Db.command("serverStatus"), so I would imagine something similar works in C#.
References:
Mongo docs for serverStatus
An answered question about serverStatus in Java
Related
I was wondering if there is something like a script that I can write on the MongoDB side that would do something like delete an item in a list if it is older than a week old etc.
I want to have the DB do this check every day. Are there some kind of automated functions that I can setup on the DB to do this?
I could just write a few small methods to do it on the userside myself, but I remember my old SQL DB having this feature. Any help would be appreciated. Thanks,
If you are using Self-Managed MongoDB, The answer is NO.
Like SQL, MongoDB doesn't support scheduled transactions. However you can run the scheduled jobs in your programming language and perform the operations. For example, https://thecodebarbarian.com/node.js-task-scheduling-with-agenda-and-mongodb
If you are using MongoDB Atlas, Then you need to check this https://docs.mongodb.com/realm/triggers/scheduled-triggers/
Then you might want to check out the MongoDB TTL feature :
https://docs.mongodb.com/manual/tutorial/expire-data/
It won't run every day like a script, but it will automatically remove data after some time.
Hope it can help !
I am going to use SQL terminology because I am new to Parse, apologies if that is confusing. I have a table in an app and in order to introduce new functionality I need to add a new column and set all the records to a default value. In SQL I would just run
update <table> set <column> = <value>;
Parse Server has MongoDB as the back end and I am not clear whether the correct approach is to directly access the MongoDB and run statements through the command line or if this would cause an issue with Parse. I found this helpful link for translating SQL syntax to MongoDB for that, https://docs.mongodb.com/manual/reference/sql-comparison/.
I also noticed that there were some tools, such as studio 3t, but the ones I saw all required expensive licenses. If direct MongoDB access is OK, any help understanding how to get to that would be helpful, I installed parse-server from the Bitnami stack on the AWS marketplace and to date I have only been interacting with it through the provided dashboard which doesn't have an "Update all records" option.
Right now my work around is to write a Swift script that runs the update in a loop, but I have to think that if I had millions or records instead of thousands this would be the incorrect approach. What is the proper environment and code to update my existing Parse server so that I can run something like the SQL above?
I'm trying to set up an app that will act as a front end to an externally updated mongo database. The data will be pushed into the database by another process.
I so far have the app connecting to the external mongo instance and pulling data out with on issues, but its not reactive (not seeing any of the new data going into the mongo database).
I've done some digging and it so far can only find that I might need to set up replica sets and use oplog, is there a way to do this without going to replica sets (or is that the best way anyway)?
The code so far is really simple, a single collection, a single publication (pulling out the last 10 records from the database) and a single template just displaying that data.
No deps that I've written (not sure if that's what I'm missing).
Thanks.
Any reason not to use Oplog? For what I've read it is the recommended approach even if your DB isn't updated by an external process, and a must if it does.
Nevertheless, without Oplog your app should see the changes on the DB made by the external process anyway. It should take longer (up to 10 seconds), but it should update.
The project in which I am working requires synchronization of data between MongoDB and SQL Server, so what is the best way for it? This synchronization should be handled by MongoDB side; does MongoDB support job scheduling?
I am new in MongoDB and I want to know few things about it. I know it is not an RDBMS but in case it is possible, then how?
Like we can write program in Oracle can we write in MongoDB. I mean directly in MongoDB, if no then which client side language can used?
As #Vasanth said, MongoDB has no native job management.
As to which client side language: well that's entirely upto you.
You can always get get a prebuilt replicator like: http://code.google.com/p/tungsten-replicator/ that might do the job for you.
As further reference, this question maybe of help to you: https://softwareengineering.stackexchange.com/questions/125980/can-sql-server-and-mongo-be-used-together
I have some collection and I want to perform action on every insert into that collection. The problem is that the code, that will do this actions is in Java. In Oracle it was possible to wrap Java or even C code into PL/SQL procedure, and then use this procedure in trigger. In CouchDB we could write a view. What would be the closest analog for MongoDB?
The best possibility I can think of is to wrap my code into REST server, and then interact with it using stored javascript.
I've already seen this question, but due to dependency on java libs, I can't use just javascript in my workflow, neither I don't want to run a new heavy service along with mongodb if there is some other way to do this.
There are a number of things to say about your request:
I have some collection and I want to perform action on every insert into that collection.
1) What you're asking for here is not really a "stored procedure", but really is a "database trigger". MongoDB does not provide any sort of "database trigger" functionality.
This is consistent with the general design goals of MongoDB, which is to provide a very fast, scalable data store without the heavy weight of traditional DBMS systems. See this presentation for more details about the design goals of MongoDB: http://www.10gen.com/presentations/mongosf2011/whymongodb
2) If there is some data processing that you'd like to perform on every insert, you'll need to do it on the client side of the MongoDB connection. This will necessarily involve writing some code in your application.
3) I'd suggest that you avoid running JavaScript within the mongod server if at all possible. The JavaScript is interpreted on the server side, so the speed of your queries will be affected. In addition, all JavaScript run in the mongod server is single-threaded, so there is no concurrency of any JavaScript execution.
I wish I had a better answer for you.