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https://issues.apache.org/jira/browse/CALCITE-4712?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17391828#comment-17391828
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Julian Hyde edited comment on CALCITE-4712 at 8/3/21, 12:19 AM:
----------------------------------------------------------------
{quote}
I see RelDistributionImpl uses ImmutableIntList, should we keep them
consistent?
{quote}
Yes - use ImmutableIntList. (I didn't notice RelDistributionImpl.)
{quote}No, the nullls are in different columns.
{quote}
So, can you give me some examples? Are you saying that {{(1, null)}} would be
in the same bucket as {{(2, null)}}; and {{(null, 'a')}} would be in the same
bucket as {{(null, 'bc')}}; and all rows with key {{(null, null)}} would be in
the same bucket?
If I were designing this, I would say 'null is just a value, and nulls are
equal'. (Which is, incidentally, how nulls behave in {{GROUP BY}}.) But then
there would be no need for a "nullsColocated" flag.
was (Author: julianhyde):
{quote}
I see RelDistributionImpl uses ImmutableIntList, should we keep them
consistent?{quote}
Yes - use ImmutableIntList. (I didn't notice RelDistributionImpl.)
{quote}
No, the nullls are in different columns.
{quote}
So, can you give me some examples? Are you saying that {{(1, null)}} would be
in the same bucket as {{(2, null)}}; and {{(null, 'a')}} would be in the same
bucket as {{(null, 'bc')}} would be in the same bucket, and all rows with key
{{(null, null)}} would be in the same bucket?
If I were designing this, I would say 'null is just a value, and nulls are
equal'. (Which is, incidentally, how nulls behave in {{GROUP BY}}.) But then
there would be no need for a "nullsColocated" flag.
> 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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