Nested match_recognize query not supported in flink SQL? - apache-flink

Question

I am using flink 1.11 and trying nested query where match_recognize is inside, as shown below :
select * from events where id = (SELECT * FROM events MATCH_RECOGNIZE (PARTITION BY org_id ORDER BY proctime MEASURES A.id AS startId ONE ROW PER MATCH PATTERN (A C* B) DEFINE A AS A.tag = 'tag1', C AS C.tag <> 'tag2', B AS B.tag = 'tag2'));
And I am getting an error as : org.apache.calcite.sql.validate.SqlValidatorException: Table 'A' not found
Is this not supported ? If not what's the alternative ?

Answer 1

I was able to get something working by doing this:
Table events = tableEnv.fromDataStream(input,
$("sensorId"),
$("ts").rowtime(),
$("kwh"));
tableEnv.createTemporaryView("events", events);
Table matches = tableEnv.sqlQuery(
"SELECT id " +
"FROM events " +
"MATCH_RECOGNIZE ( " +
"PARTITION BY sensorId " +
"ORDER BY ts " +
"MEASURES " +
"this_step.sensorId AS id " +
"AFTER MATCH SKIP TO NEXT ROW " +
"PATTERN (this_step next_step) " +
"DEFINE " +
"this_step AS TRUE, " +
"next_step AS TRUE " +
")"
);
tableEnv.createTemporaryView("mmm", matches);
Table results = tableEnv.sqlQuery(
"SELECT * FROM events WHERE events.sensorId IN (select * from mmm)");
tableEnv
.toAppendStream(results, Row.class)
.print();
For some reason, I couldn't get it to work without defining a view. I kept getting Calcite errors.
I guess you are trying to avoid enumerating all of the columns from A in the MEASURES clause of the MATCH_RECOGNIZE. You may want to compare the resulting execution plans to see if there's any significant difference.