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https://issues.apache.org/jira/browse/CALCITE-4712?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17391776#comment-17391776
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Julian Hyde commented on CALCITE-4712:
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Makes sense. A few comments:
* Would this be a class that implements {{interface RelDistribution}}? If so,
would you use {{RelDistribution.Type.HASH_DISTRIBUTED}} or add a new enum
constant?
* I'd rename "bucketNum" to "bucketCount" ("num" can sometimes mean "ordinal"
rather than "cardinality");
* I'd rename "hashFunc" to "hashFunctionName" (no point in abbreviation);
* Consider changing the type of "keys" to "ImmutableList<Integer>" (see [why we
changed the type of
AggregateCall.argList|https://github.com/apache/calcite/blob/4bc916619fd286b2c0cc4d5c653c96a68801d74e/core/src/main/java/org/apache/calcite/rel/core/AggregateCall.java#L55]);
* an example of "equivKeys" would be useful;
* if {{nullsColocated}}, would you store (1, null) in the same bucket as (null,
'a')?
> Add RelHashDistribution
> -----------------------
>
> Key: CALCITE-4712
> URL: https://issues.apache.org/jira/browse/CALCITE-4712
> Project: Calcite
> Issue Type: Bug
> Components: core
> Reporter: Haisheng Yuan
> Priority: Major
>
> Add RelHashDistribution. The hash distribution should have the following
> properties:
> {code:java}
> 1. ImmutableIntList keys; // distribution keys
> 2. ImmutableList<ImmutableBitSet> equivKeys; // equivalent keys for each
> distribution key
> 3. int bucketNum; // number of buckets or shards
> 4. boolean nullsColocated; // are NULLS colocated?
> 5. String hashFunc; // name or identity of hash function
> {code}
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