JingsongLi commented on a change in pull request #10756:
[FLINK-15465][FLINK-11964][table-runtime-blink] Fix hash table bugs
URL: https://github.com/apache/flink/pull/10756#discussion_r363143078
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File path:
flink-table/flink-table-runtime-blink/src/main/java/org/apache/flink/table/runtime/hashtable/BaseHybridHashTable.java
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@@ -516,4 +511,10 @@ public static int hash(int hashCode, int level) {
return code >= 0 ? code : -(code + 1);
}
+ /**
+ * Partition level hash again, for avoid two layer hash conflict.
+ */
+ static int partitionLevelHash(int hash) {
+ return hash ^ (hash >>> 16);
+ }
Review comment:
Thanks for involving this.
> with most high bits equal to 0
Good point, but it should not.
- In `BinaryHashTable`: HashCode is from murmurhash, it is good.
- In `LongHybridHashTable`: HashCode is from `hashLong`, it is good too.
`hash ^ (hash >>> 16)` is just from `HashMap.hash`, I think it is OK.
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