CODEWITHSUNDEEP
node.jsmongodbmongoose
Mike P
Mike P

Reputation: 2877

Mongo Date or Number (epoch) as index?

I have a query I run often where I use the Date to sort by. Basically I want to grab the next user due for some "processing" based on the last time they were processed, but I don't want to process users more often than every X minutes.

I have this query;

Users.findOne({'status':'active',  'lastCheck': {"$lt": sinceTime}).sort({"lastCheck": "ascending"}).exec(callback);

I know that for this to work I need to set lastCheck as an index, but this is a Date. Is it better to store that as a Number or Date?

Maybe there is a better way to do this altogether?

Thanks in advance

Upvotes: 0

Views: 652

Answers (1)

yǝsʞǝla
yǝsʞǝla

Reputation: 16422

From here: "BSON Date is a 64-bit integer that represents the number of milliseconds since the Unix epoch (Jan 1, 1970).". So if you store it as millis you would not get any benefits really. I think it's better to store it as Date because you get all kinds of data integrity checks and conversions in your stack. Using $lt is absolutely appropriate with dates.

As for the index you'll have to pick carefully. MongoDB can use only one index in the query condition. Here you are querying by 2 fields, so maybe a compound index would be better - depends on your data. Perhaps I would even create only 1 index on lastCheck. You can use that same index in the sort since you are sorting by that field. Mongo is able to use another index for sorting purposes.

Upvotes: 1

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