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https://issues.apache.org/jira/browse/HIVE-15192?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Vineet Garg updated HIVE-15192:
-------------------------------
Issue Type: Sub-task (was: Task)
Parent: HIVE-15456
> Use Calcite to de-correlate and plan subqueries
> -----------------------------------------------
>
> Key: HIVE-15192
> URL: https://issues.apache.org/jira/browse/HIVE-15192
> Project: Hive
> Issue Type: Sub-task
> Components: Logical Optimizer
> Reporter: Vineet Garg
> Assignee: Vineet Garg
> Labels: sub-query
> Fix For: 2.2.0
>
> Attachments: HIVE-15192.10.patch, HIVE-15192.2.patch,
> HIVE-15192.3.patch, HIVE-15192.4.patch, HIVE-15192.5.patch,
> HIVE-15192.6.patch, HIVE-15192.7.patch, HIVE-15192.8.patch,
> HIVE-15192.9.patch, HIVE-15192.patch
>
>
> HIVE currently tranform subqueries into SEMI-JOIN or LEFT OUTER JOIN. This
> transformation occurs on query AST before generating logical plan. These
> transformations are described at [Link to original spec |
> https://issues.apache.org/jira/secure/attachment/12614003/SubQuerySpec.pdf].
> Such transformations aren't able to handle a lot of subqueries, as a result
> HIVE imposes various restrictions on the type of queries it could handle e.g.
> Hive disallows nested subqueries. All current restrictions are detailed in
> above linked document.
> This patch is 1st phase of getting rid of these transformations and leverage
> Calcite's functionality to plan such queries.
> Next phases will be lifting restrictions one by one.
> Note that this patch already lifts one restriction *Restriction.6.m* (The LHS
> in a SubQuery must have all its Column References be qualified)
> Known issues with this patch are:
> * Return path tests fails for various reasons and are currently disabled. We
> plan to fix and re-enable this later.
> * Semi-join optimization (HIVE-15227) is disabled by default as it doesn't
> work with this patch. We plan to fix this and re-enable it by default.
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