[GitHub] [incubator-pinot] mcvsubbu commented on issue #5751: Support Serving Latest Offline Segments Immediately

[GitBox <gi...@apache.org>]

mcvsubbu commented on issue #5751:
URL: https://github.com/apache/incubator-pinot/issues/5751#issuecomment-663679922


   Here is my suggested approach.
   1. Create a config in table that indicates that for a table we need the time boundary to be next unit up. (i.e. if daily push, next day, if hourly the next hour. etc.)
   2. Change the time boundary code to move up the time boundary when new segments are added to the table.
   
   In this case, there is no new API, but for use cases that have multiple segments, the time boundary will be advanced when the first segment is pushed. This will lead to inconsistency. 
   
   Pinot currently has the inconsistency problem only if RT is not there, but we will be introducing a new one now.
   
   We can, however, introduce an API as well, which can send out a message to the brokers to advnce time bondary. This API will be invoked by the push job when all segments are pushed. This iwll reduce the inconsistency window to some narrow cases such as:
   (1)  Three segments are being pushed. After the first one, a broker restarts, and lokoing at the table config, and the recent timestamp, advances the boundary. Since the other two segments are not pushed yet, the broker has no way of knowing that a message is going to come by later. Corner case, but maybe we can leave that for the day when we support "atomic" push of data.
   (2). Three segments are being pushed. The push complets, but the external view is not yet updated (slow server, slow helix, whatever). The broker meanwhile gets the message to move time boundary. 
   
   The second one is more likely to happen, but either one is a bad experience for the application. 
   
   Some mitigation may be to include the segment names in the controller api and the controller waits for the EV of these segments to be ONLINE before issuing a message, but that is also not complete. Broker may still not see the new EV
   
   Ideas?


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