Hi everyone, Flink's CEP library is a great library for complex event processing, more and more customers are expressing their interests in it. But it also has some limitations that users usually have to write a lot of code even for a very simple pattern match use case as it currently only supports the Java API. We have investigated some popular CEP products such as esper [1] and siddhi [2] and found that most of these CEP products support SQL-like expressions such as EPL to describe the match pattern. But these solutions also have the drawbacks that the pattern match languages are not standard SQL, the learn curve is steep for users and it's impossible to integrate them into the Flink Table API & SQL. We find that Oracle's CEP solution CQL [3] supports a new pattern recognition clause match_recognize which is a pattern recognition clause proposed in this paper [4]. It proposes a set of new syntaxes to define match pattern in sql expression. Calcite already supports part of this standard [5]. I think it will be of great value to support expressing pattern recognition clause with match_recognize clause by integrating it with Flink Table API & SQL and the Flink CEP library. Any thoughts?
[1] http://www.espertech.com [2] https://github.com/wso2/siddhi [3] https://docs.oracle.com/middleware/1213/eventprocessing/cql-reference/GUID-34D4968E-C55A-4BC7-B1CE-C84B202217BD.htm#CQLLR1531 [4] http://web.cs.ucla.edu/classes/winter17/cs240B/notes/row-pattern-recogniton-11.pdf [5] https://issues.apache.org/jira/browse/CALCITE-1570 Best Regards, Dian
