Ted Yu created KYLIN-3398:
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Summary: Inaccurate arithmetic operation in
LookupTableToHFileJob#calculateShardNum
Key: KYLIN-3398
URL: https://issues.apache.org/jira/browse/KYLIN-3398
Project: Kylin
Issue Type: Bug
Reporter: Ted Yu
There're two issues with the following code:
{code}
private int calculateShardNum(KylinConfig kylinConfig, long dataSize) {
long shardSize = kylinConfig.getExtTableSnapshotShardingMB() * 1024 *
1024;
return dataSize < shardSize ? 1 : (int) (Math.ceil(dataSize /
shardSize));
{code}
getExtTableSnapshotShardingMB returns an int. The multiplication is done using
32-bit arithmetic, and then used in a context that expects an expression of
type "long".
Second, Math.ceil expects a double. The integer division would lose some
precision.
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