clintropolis commented on a change in pull request #7133: Time Ordering On Scans URL: https://github.com/apache/incubator-druid/pull/7133#discussion_r270205022
########## File path: docs/content/querying/scan-query.md ########## @@ -24,7 +24,16 @@ title: "Scan query" # Scan query -Scan query returns raw Druid rows in streaming mode. +The Scan query returns raw Druid rows in streaming mode. The biggest difference between the Select query and the Scan +query is that the Scan query does not retain all the returned rows in memory before they are returned to the client. +The Select query _will_ retain the rows in memory, causing memory pressure if too many rows are returned. +The Scan query can return all the rows without issuing another pagination query. + +In addition to straightforward usage where a Scan query is issued to the Broker, the Scan query can also be issued Review comment: I think it's probably ok, i think it just flows strange for me when I read the section. It's because the things aren't really related but don't really feel separated. For future work it might be nice to overhaul the scan query documentation, maybe drop mention of the legacy mode and the `valueVector` result format and maybe re-arrange some things. I still feel querying a historical directly is less important than describing the scan query itself, and should be pushed to the end of the docs into an 'advanced' section that describes using the scan query as a means of parallel export into another query system or whatever, but all of this can be done in a future PR ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
