[APEXMALHAR-2244] Optimize WindowedStorage and Spillable data structures for time series

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 3.6.0
• Assignee: Siyuan Hua
• Reporter: David Yan
• Created: 19/Sep/16 23:36
• Updated: 02/Dec/16 21:12
• Resolved: 31/Oct/16 19:36

Description

The spillable data structures currently does not make any assumption about the key that is used in Managed State, and as a result, it uses ManagedStateImpl to interface with Managed State and uses time buckets that are based on the apex window id. But for WindowedStorage used by WindowedOperator, the key to the storage is a window, which is event time based. Using the default ManagedStateImpl would be very inefficient for event time based keys, since it would write data that would belong to the same window to different time buckets.

On a high level, the below summarizes roughly what needs to be done:

1. a way to tell the spillable data structures to use the ManagedTimeUnifiedStateImpl
2. a way to tell the spillable data structures how to extract the timestamp from the key. Note that in the case of WindowedOperator, the timestamp should be the end timestamp of the window (beginTimeMillis + durationMillis), not the begin timestamp.
3. a way to tell the spillable data structures how to assign the time bucket given that timestamp
4. with point 3, the spillable implementations of WindowedStorage will need to take a config parameter that says how much time (in millis) is each time bucket
5. only purge a time bucket when all keys that belong to that time bucket are removed and the apex window id of the first window in which the keys are all removed has been committed

Issue Links

• is related to: APEXMALHAR-2271 Special SpillableSetMultimap<K, Window.SessionWindow<K>> handling in ManagedState in SpillableSessionWindowedStorage
• relates to: APEXMALHAR-2252 Document AbstractManagedStateImpl subclasses
• links to: GitHub Pull Request #434