Mongoose .save very slow large sub-document

Question

We are facing a very annoying issue with Mongoose. The save method takes around 500 / 600ms and it is very CPU consuming.

We have a sub-document with 50000 array elements which gets a new element (history) every each update using push.

Here is the code:

..... very large function 

variable.value = parseFloat(value);
variable.history.push([{
        value: parseFloat(value),
        timestamp: dateNow
}]);
await variable.save(); 
..... end function

I have indexes on history and _id.

Any hint on why this is taking so long and consuming 60%...80% CPU ?

Thanks

xiaolin xiaolin · Accepted Answer · 2019-11-08T04:36:40

I had a similar issue and looked all over and there doesn't seem to be a reasonable solution other than modifying your schema.

My save function would take very long after the document had a large sub-document array with over 100K entries.

I removed the array from the document and created a new schema. Instead of pushing to the sub-document array, I create a new one.

Mongoose .save very slow large sub-document

1 Answers