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Prevent division by 0 #15899

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Merged
sopel39 merged 2 commits into from
Jan 31, 2023
Merged

Prevent division by 0 #15899

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18bd09e
Fix formatting
sopel39 Jan 30, 2023
6e1bff2
Prevent division by 0
sopel39 Jan 30, 2023
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15 changes: 9 additions & 6 deletions core/trino-main/src/main/java/io/trino/operator/exchange/UniformPartitionRebalancer.java
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Original file line number Diff line number Diff line change
Expand Up @@ -47,14 +47,14 @@
* Example:
* <p>
* Before: For three writers with skewed partitions
* Writer 1 -> No partition assigned -> 0 bytes
* Writer 2 -> No partition assigned -> 0 bytes
* Writer 3 -> Partition 1 (100MB) + Partition 2 (100MB) + Partition 3 (100MB) -> 300 MB
* Writer 1 -> No partition assigned -> 0 bytes
* Writer 2 -> No partition assigned -> 0 bytes
* Writer 3 -> Partition 1 (100MB) + Partition 2 (100MB) + Partition 3 (100MB) -> 300 MB
* <p>
* After scaling:
* Writer 1 -> Partition 1 (50MB) + Partition 3 (50MB) -> 100 MB
* Writer 2 -> Partition 2 (50MB) -> 50 MB
* Writer 3 -> Partition 1 (150MB) + Partition 2 (150MB) + Partition 3 (150MB) -> 450 MB
* Writer 1 -> Partition 1 (50MB) + Partition 3 (50MB) -> 100 MB
* Writer 2 -> Partition 2 (50MB) -> 50 MB
* Writer 3 -> Partition 1 (150MB) + Partition 2 (150MB) + Partition 3 (150MB) -> 450 MB
*/
@ThreadSafe
public class UniformPartitionRebalancer
Expand Down Expand Up @@ -313,6 +313,9 @@ private boolean isPartitionRebalanced(int partitionId)

private long estimatePartitionWrittenBytesSinceLastRebalance(WriterId writer, long partitionRowCount)
{
if (writerRowCountSinceLastRebalance[writer.id] == 0) {
return 0L;
}
return (writerPhysicalWrittenBytesSinceLastRebalance[writer.id] * partitionRowCount) / writerRowCountSinceLastRebalance[writer.id];
}
}
Expand Down