Hi, Our company have recently started testing MongoDB services and we did a write operation of about 17.2 GB data with 196.430681 million documents ( 94 bytes per document, therefore approximately 10 documents per write i.e., 1 KB chunk). So, from our understanding only 19.64 million WPU must have been in the billing while we are charged for 196.4 million WPU, we would like to understand this process.
Furthermore, why are we being charged for the data transfer while we have never attempted to transfer any data from MongoDB server. Is this because of using MongoDB compass for importing .csv data? and is there any other alternative for this write to avoid data transfer?
I would greatly appreciate your advice as this will help us have a precise estimate on future projects.
Hi @itscotecgroup_N_A Here are a couple of good resources to better understand Serverless pricing (link1 , link2). In your case since the writes are what drove your invoice, we will dive deeper into that. We calculate WPUs (write processing units) by writes to a document. I.E. for every 1KB written to a document and its corresponding index, we charge the customer 1 WPU. Therefore, WPUs do not depend on the number of write operations but on the number of documents and corresponding indexes that are written to. From link2 (above), we see that 1 Million WPUs are priced between $0.90 and $2.20 depending on the region. Let’s assume the price is $1 per million WPUs. In your case, since each document was less than a kilobyte (94bytes as determined above), each document will cost 1 WPU (assuming each document is under 1KB in size). Therefore, the cost of 196.43 million documents is 196.43 million WPUs. This is in line with the invoice that you see.
Please let me know if you have any further questions.