Quotas

Logs API limits are applied per API key. This means that limits for “App 1” do not affect limits for “App 2”.

After sending the request, Logs API queues it for further processing. The maximum acceptable number of request in a queue per API key is 3. If you have exceeded the limit, the Logs API returns:

HTTP/1.1 429 Too Many Requests
Content-Type: text/plain

There are already 3 enqueued queries for given application_id. Wait until they are completed.
Note. The time to wait depends on the current server load and the amount of data your app has to process.