GitHub user dongjoon-hyun opened a pull request:
https://github.com/apache/spark/pull/15868
[SPARK-18413][SQL] Control the number of JDBC connections by repartition
with `numPartition` JDBCOption
## What changes were proposed in this pull request?
This PR aims to control the number of JDBC connections by repartition with
`numPartition` (`JDBC_NUM_PARTITIONS` JDBCOption). Currently,
`JDBC_NUM_PARTITIONS` is documented as an optional parameter for only reading.
**Reported Scenario**
For the following cases, the number of connections becomes 200 and database
cannot handle all of them.
```sql
CREATE OR REPLACE TEMPORARY VIEW resultview
USING org.apache.spark.sql.jdbc
OPTIONS (
url "jdbc:oracle:thin:@10.129.10.111:1521:BKDB",
dbtable "result",
user "HIVE",
password "HIVE"
);
-- set spark.sql.shuffle.partitions=200
INSERT OVERWRITE TABLE resultview SELECT g, count(1) AS COUNT FROM
tnet.DT_LIVE_INFO GROUP BY g
```
## How was this patch tested?
Manual by using `Client Connection Tab` of `MySQLWorkbench`. After creating
table t1 by `CREATE TABLE t1 (a INT)` in MySQL, do the following.
```scala
SPARK_HOME=$PWD bin/spark-shell --driver-memory 4G --driver-class-path
mysql-connector-java-5.1.40-bin.jar
scala> sql("CREATE OR REPLACE TEMPORARY VIEW v1 USING
org.apache.spark.sql.jdbc OPTIONS (url 'jdbc:mysql://localhost:3306/t', dbtable
't1', user 'root', password '', numPartitions '1')")
scala> sql("INSERT OVERWRITE TABLE v1 SELECT 1").show
scala> sql("CREATE OR REPLACE TEMPORARY VIEW v1 USING
org.apache.spark.sql.jdbc OPTIONS (url 'jdbc:mysql://localhost:3306/t', dbtable
't1', user 'root', password '', numPartitions '20')")
scala> sql("INSERT OVERWRITE TABLE v1 SELECT 1").show
```
The total connection is increased by 3 and 20, respectively for the first
and second insertion.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/dongjoon-hyun/spark SPARK-18413
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/15868.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #15868
----
commit e29974a08da14b63aec1f6fc9798bac532e4d97f
Author: Dongjoon Hyun <dongj...@apache.org>
Date: 2016-11-13T04:07:39Z
[SPARK-18413][SQL] Control the number of JDBC connections by repartition
with `numPartition` JDBCOption
----
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