Hi,
The semantics of a query do not depend on the way that it is used.
praiseAggr is a table that grows by one row per second and article_id. If
you use that table in a join, the join will fully materialize the table.
This is a special case because the same row is added multiple times, so the
state won't grow that quickly, but the performance will decrease because
for each row from article will join with multiple (a growing number) of
rows from praiseAggr.
Best, Fabian
2018-08-21 12:19 GMT+02:00 徐涛 <happydexu...@gmail.com>:
> Hi All,
> var praiseAggr = tableEnv.sqlQuery(s"SELECT article_id FROM praise GROUP
> BY HOP(updated_time, INTERVAL '1' SECOND,INTERVAL '3' MINUTE) , article_id"
> )
> tableEnv.registerTable("praiseAggr", praiseAggr)
>
> var finalTable = tableEnv.sqlQuery(*s**”**SELECT 1 FROM article a join
> praiseAggr p on a.article_id=p.article_id" *)
> tableEnv.registerTable("finalTable", finalTable)
>
> I know that praiseAggr, if written to sink, is append mode , so if a
> table joins praiseAggr, what the table “see”, is a table contains the
> latest value, or a table that grows larger and larger? If it is the later,
> will it introduce performance problem?
> Thanks a lot.
>
>
> Best,
> Henry
>
