Hi Henry,
Both sql output incrementally.
However there are some problems if you use retract sink. You have to pay
attention to the timestamp field since each time the value is different.
For example, if the value is updated from 1 to 2,
previous row: add (a, 1, 2018-08-20 20:18:10.286)
retract row: delete (a, 1, 2018-08-20 20:18:10.386)
new row: add (a, 2, 2018-08-20 20:18:10.486)
The retract row is different from the previous row because of the time
field.
Of course, this problem should be fixed later.
Best, Hequn
On Mon, Aug 20, 2018 at 6:43 PM, 徐涛 <happydexu...@gmail.com> wrote:
> Hi All,
> Like the following code,If I use retract stream, I think Flink is able to
> know which item is modified( if praise has 10000 items now, when one item
> comes to the stream, only very small amount of data is write to sink)
>
> var praiseAggr = tableEnv.sqlQuery(*s"SELECT article_id,hll(uid) as PU
> FROM praise group by article_id**”* )
>
> tableEnv.registerTable("finalTable", praiseAggr)
>
> tableEnv.sqlUpdate(s"insert into sinkTableName SELECT * from
> finalTable")
>
>
> But if I use the following sql, by adding a dynamic timestamp
> field:
> var praiseAggr = tableEnv.sqlQuery(s"SELECT article_id,hll(uid) as
> PU,LOCALTIMESTAMP
> as update_timestamp* FROM praise group by article_id**”* )
> Is the whole table flush to the sink? Or only the incremental value
> will flush to the sink? Why?
>
> Thanks,
> Henry
>
>
