MongoDB Sizing

Overview

The aggregate record size depends on the number of APIs and Keys you have. Each counter size ~50b, and every aggregated value has its own counter.

So an hourly aggregate record is computed like this: 50 * active_apis + 50 * api_versions + 50 * active_api_keys + 50 * oauth_keys, etc.

The average aggregate record size (created hourly) on our cloud is about ~ 40KB (a single record includes all the aggregate stats mentioned above).

So for 1 million requests per day, it will generate 1KB * 1M request stats (1GB) + 24 * 40KB aggregate stats (~1MB).

Per month: 30GB request logs + 30MB aggregate logs

MongoDB Working Data

Working data in terms of MongoDB is the data you query most often. The graphs displayed on the Tyk Dashboard, except for the Log browser, use aggregated data.

So if you rely only on this kind of analytic data, you will not experience issues with working data and memory issues. It is literally hundreds of MBs.

Even if you use the Log browser, its usage access is usually quite random, and it is unlikely that you check requests for every request. So it can’t be called working data. And it is ok to store it on disk, and allow MongoDB to do the disk lookups to fetch the data.

Note, that in order to do fast queries, even from the disk, MongoDB uses indexes. MongoDB recommends that indexes should fit into memory, and be considered working data, but only the part of the index which is commonly used. For example the last month of data.

For an aggregate collection, the average index size is 6% from the overall collection. For requests stats it is around 30%.

Example

If you serve 1 million requests per day, and require fast access to the last seven days of request logs (usually way less, and the performance of the log viewer is not a concern), with 3 months of aggregated logs, the memory requirements for MongoDB can be as follows:

Request_logs_index ( 30% * (1GB * 7) ) + aggregated(3month * 30MB) ~= 2.1GB + 90MB = ~ 2.2GB

In addition to storing working data in memory, MongoDB also requires space for some internal data structures. In general multiplying the resulting number by 2x should be enough. In the above example, your MongoDB server should have around 4.4GB of available memory.

MongoDB Database Storage Calculator

You can calculate your MongoDB storage requirements by entering your known values in the middle section of the calculator settings below: