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https://issues.apache.org/jira/browse/CALCITE-4705?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17564541#comment-17564541
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Jiajun Xie commented on CALCITE-4705:
-------------------------------------
In databricks:
[https://docs.databricks.com/delta/join-performance/skew-join.html]
The hint is named as *skew,* and the options contain string and number,
calcite can't parse it. So I create new Jira ticket to disscuss.
{code:java}
SELECT /*+ SKEW('orders', 'o_custId', 0) */ * FROM orders, customers WHERE
o_custId = c_custId {code}
I only found */*+ skewjoin(a(c0, c1)) */* in MaxCompute:
https://help.aliyun.com/document_detail/203410.html
Any other database support it? [~hyuan]
> Support hints like /*+ skewjoin(a(c0, c1)) */
> ---------------------------------------------
>
> Key: CALCITE-4705
> URL: https://issues.apache.org/jira/browse/CALCITE-4705
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Affects Versions: 1.27.0
> Reporter: jibiyr
> Assignee: jibiyr
> Priority: Minor
>
> Dear community,
> calcite parse support hint now,but it can not parse hint like follow,
> _*select /*+ skewjoin(a(c0, c1)) */ * from T0 a join T1 b on a.c0 = b.c0,*_
> this is the bnf which is calcite supported now,
> {code:java}
> //
> hint:
> hintName
> | hintName '(' hintOptions ')'
> hintOptions:
> hintKVOption [, hintKVOption ]*
> | optionName [, optionName ]*
> | optionValue [, optionValue ]*
> hintKVOption:
> optionName '=' stringLiteral
> | stringLiteral '=' stringLiteral
> optionValue:
> stringLiteral
> | numericLiteral
> {code}
> I think the hintOptions should support the expression pattern,like a(c0,c1).
> And this pattern can be parsed by spark/presto now.
>
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