update cloud env (#1057)

Co-authored-by: François Massot <[email protected]>

Author: PSeitz

docs/administration/cloud-env.md

@@ -1,25 +1,40 @@
 ---
-title: Operating in the cloud
+title: Cloud operation costs
 sidebar_position: 1
 ---
 
-Quickwit has only been tested on AWS S3. This page sums up what we have learned from that.
+Quickwit has been tested on Amazon S3. This page sums up what we have learned from that experience.
 
 ## Data transfers costs and latency
 
-Cloud providers charge for data transfers in and out of their networks. In addition, querying an index from a remote machine adds some extra latency. For those reasons, we recommend that you test and use the Quickwit from an instance located within your cloud provider's network.
+Cloud providers charge for data transfers in and out of their networks. In addition, querying an index from a remote machine adds some extra latency.
+For those reasons, we recommend that you test and use the Quickwit from an instance located within your cloud provider's network.
 
 ## Optimizing bandwidth with wisely chosen instances
 
-To get the best performance out of Quickwit search from object storage, we recommend picking an instance with high network bandwidth.
-In our experience, `c5n.2xlarge` instances offer the bigger bang for your buck.
+We recommend picking instances with high network performance to allow faster downloads from Amazon S3. In our experience, `c5n.2xlarge` instances offer the best bang for your buck.
 
-## GET/PUT requests costs
+## Requests cost
 
-A final note on object storage requests costs. These are [quite low](https://aws.amazon.com/s3/pricing/) actually, $0,0004 / 1000 requests for GET and $0.005 / 1000 requests for PUT on AWS S3, so you don't need to worry too much about it.
+A final note on object storage requests costs. These are [quite low](https://aws.amazon.com/s3/pricing/) actually, $0,0004 / 1000 requests for GET and $0.005 / 1000 requests for PUT on AWS S3.
 
-Indeed when indexing, Quickwit generates [splits](../overview/architecture.md#splits) of 5 millions documents each and then
-upload them. As they are composed of 9 files, this generates 9 PUT requests per split. When querying one term, Quickwit only needs to make 3 GET requests per split.
+### PUT requests
 
-Of course, these requests could add up quickly if you have a large amount of requests.
+During indexing, Quickwit uploads new splits on Amazon S3 and progressively merges them until they reach 10 million documents that we call “mature splits”. Such splits have a typical size between 1GB and 10GB and will usually require 2 PUT requests to be uploaded (1 PUT request / 5GB).
+
+With default indexing parameters `commit_timeout_secs` of 60 seconds and `merge_policy.merge_factor` of 10 and assuming you want to ingest 1 million documents every minute, this will cost you less than $1 / month.
+
+### GET requests
+
+When querying, Quickwit needs to make multiple GET requests:
+
+```jsx
+#num requests = #num splits * ((#num search fields * #num terms * 3) + #num fast fields)
+```
+
+The above formula assumes that the hotcache is cached, which will be loaded after the first query for every split.
+
+When positions are not enabled, only 2 GET requests will be executed per term.
+
+These requests costs could add up quickly if you have a high number of splits or QPS > 10.
 Don't hesitate to [contact us](mailto:[email protected]) if this is the case :).