Github user hotou commented on a diff in the pull request:
https://github.com/apache/spark/pull/4701#discussion_r25074390
--- Diff: core/src/main/scala/org/apache/spark/rdd/JdbcRDD.scala ---
@@ -64,8 +64,8 @@ class JdbcRDD[T: ClassTag](
// bounds are inclusive, hence the + 1 here and - 1 on end
val length = 1 + upperBound - lowerBound
(0 until numPartitions).map(i => {
- val start = lowerBound + ((i * length) / numPartitions).toLong
- val end = lowerBound + (((i + 1) * length) / numPartitions).toLong -
1
+ val start = lowerBound + ((BigDecimal(i) * length) /
numPartitions).toLong
--- End diff --
@srowen
1. BigInt in scala actually works, I should change to that.
2. The overflow is not necessary to be only the last partition, in my test
case it was the last 4 partitions
3. I think the current algo give us better partitions than the fix interval
algo, for the reason in above comment, would you agree with that ?
4. The current algo does +1 on the length and -1 on the end of each
interval, I think that works fine.
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