When searching or indexing, you might run into an error stating
The Acquia Search flood control mechanism has blocked a Solr query due to API usage limits
This is due to the default flood control limitations that come pre-shipped with Acquia Search. Fortunately those configurations can be changed.
Following the below instructions and overriding the limits to a high value may result in your application's usage exceeding your contractual limits. If this happens you may contacted by our Account Management/Sales team, or in extreme cases, your shared Search service could be temporarily disabled to keep platform integrity. See our Acquia Search Product Guide: Entitlements and Acquia Search Documentation: Staying under limits pages or more information.
Depending on the scenario where you encounter this error, you might want to tackle this issue in different ways.
The "catch-all" way of dealing with this issue would be to increase those flood control limit values. However, there is a different configuration for each type of query. That means that /select queries can have a different value with regards to flood control limits compared to /update queries.
If you are running into the error while searching, then you would want to increase the /select limit as such, "200" being an example value
drush --uri=www.example.com cset acquia_search.settings flood_limit.select.limit 200
If on the other hand you are running into the error while indexing, you could either increase the flood control limit for update requests - again "1000" is an example value
drush --uri=www.example.com cset acquia_search.settings flood_limit.update.limit 1000
... or, for this scenario, you could also increase the amount of entities processed in each batch, thus making the requests less frequent, but with a larger payload; If you do that you might not have to tweak the flood control limitation.
When using drush to index you can use --batch-size to achieve that
# Index in batches of 500. Note: if you run out of memory, use smaller batches. drush --uri=www.example.com search-api:index --batch-size=500
See our Acquia Search Documentation: Staying under limits document page.