I need it cached to improve throughput ,only hope it can be refreshed once a 
day not every batch.


> On Nov 13, 2017, at 4:49 PM, Burak Yavuz <brk...@gmail.com> wrote:
> 
> I think if you don't cache the jdbc table, then it should auto-refresh.
> 
> On Mon, Nov 13, 2017 at 1:21 PM, spark receiver <spark.recei...@gmail.com 
> <mailto:spark.recei...@gmail.com>> wrote:
> Hi 
> 
> I’m using struct streaming(spark 2.2)  to receive Kafka msg ,it works great. 
> The thing is I need to join the Kafka message with a relative static table 
> stored in mysql database (let’s call it metadata here).
> 
> So is it possible to reload the metadata table after some time interval(like 
> daily ) without restart running struct streaming?
> 
> Snippet code as following :
> // df_meta contains important information to join with the dataframe read 
> from kafka
> val df_meta = spark.read.format("jdbc").option("url", 
> mysql_url).option("dbtable", "v_entity_ap_rel").load()
> df_meta.cache()
> val df = spark.readStream
>   .format("kafka")
>   .option("kafka.bootstrap.servers", 
> “x.x.x.x:9092").option("fetch.message.max.bytes", 
> "50000000").option("kafka.max.partition.fetch.bytes", "50000000")
>   .option("subscribe", "rawdb.raw_data")
>   .option("failOnDataLoss", true)
>   .option("startingOffsets", "latest")
>   .load()
>   .select($"value".as[Array[Byte]])
>   .map(avroDeserialize(_))
>   .as[ApRawData].select("APMAC", "RSSI", "sourceMacAddress", "updatingTime")
>   .join(df_meta.as <http://df_meta.as/>("b"), $"a.apmac" === $"b.apmac”)
> 
> df.selectExpr("ENTITYID", "CLIENTMAC", "STIME", "case when a.rrssi>=b.rssi 
> then '1' when a.rrssi < b.nearbyrssi then '3' else '2' end FLAG", 
> "substring(stime,1,13) STIME_HOUR")
>   .distinct().writeStream.format("parquet").partitionBy("STIME_HOUR")
>   .option("checkpointLocation", 
> "/user/root/t_cf_table_chpt").trigger(ProcessingTime("5 minutes"))
>   .start("T_CF_TABLE")
>   .awaitTermination()
> 
> Mason
> 

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