[ https://issues.apache.org/jira/browse/SPARK-18124?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Michael Armbrust reassigned SPARK-18124: ---------------------------------------- Assignee: Michael Armbrust (was: Tathagata Das) > Implement watermarking for handling late data > --------------------------------------------- > > Key: SPARK-18124 > URL: https://issues.apache.org/jira/browse/SPARK-18124 > Project: Spark > Issue Type: Sub-task > Components: SQL, Streaming > Reporter: Tathagata Das > Assignee: Michael Armbrust > > Whenever we aggregate data by event time, we want to consider data is late > and out-of-order in terms of its event time. Since we keep aggregate keyed by > the time as state, the state will grow unbounded if we keep around all old > aggregates in an attempt consider arbitrarily late data. Since the state is a > store in-memory, we have to prevent building up of this unbounded state. > Hence, we need a watermarking mechanism by which we will mark data that is > older beyond a threshold as “too late”, and stop updating the aggregates with > them. This would allow us to remove old aggregates that are never going to be > updated, thus bounding the size of the state. > Here is the design doc - > https://docs.google.com/document/d/1z-Pazs5v4rA31azvmYhu4I5xwqaNQl6ZLIS03xhkfCQ/edit?usp=sharing -- This message was sent by Atlassian JIRA (v6.3.4#6332) --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org