caican00 commented on a change in pull request #35764:
URL: https://github.com/apache/spark/pull/35764#discussion_r826614621
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File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/jdbc/JDBCOptions.scala
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@@ -111,6 +111,9 @@ class JDBCOptions(
// the number of partitions
val numPartitions = parameters.get(JDBC_NUM_PARTITIONS).map(_.toInt)
+ // the default number of partitions
+ val defaultNumPartitions = parameters.getOrElse(DEFAULT_NUM_PARTITIONS,
"10").toInt
Review comment:
> Same question here :) Do we really need a default? If the users want
to have multiple partitions, shouldn't they specify this explicitly?
@huaxingao
1. if users want to change partition nums, they only need to specify
`DEFAULT_NUM_PARTITIONS` explicitly and do not need to specify any more
parameters, jdbc will automatically calculate the upper and lower bounds of
partitions using primary key
2. If users do not specify any parameters, then we(jdbc) need a default
value to determine the base number of partitions
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