修剪mongo对象大小

Question

This is my document:

{
    "_id": {
        "$oid": "58e9a13999447d65550f4dd6"
    },
    "prices": {
        "20170409": 701.09,
        "20170408": 700.07
    },
    "stock": {
        "20170409": 0,
        "20170408": 0
    }
}

I append a lot of fields in document objects (prices, stock) but over time it ends up being huge, and thats just one document. I have 200k documents and each have prices and stock objects.

Wondering if there's any way I could keep those object size to 30 fields max, that is, older entries purged on reaching the limit?

Answer 1

Take a look here! You can do it with a combination of $push and $slice, the example on the link sort the array too, don't know if that is your need, but I think you will have a good start from there.