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Date: Fri, 16 Dec 2016 16:01:01 +0000 (UTC)
From: "Ashutosh Chauhan (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (HIVE-15192) Use Calcite to de-correlate and
 plan subqueries
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archived-at: Fri, 16 Dec 2016 16:01:03 -0000


    [ https://issues.apache.org/jira/browse/HIVE-15192?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15754801#comment-15754801 ] 

Ashutosh Chauhan commented on HIVE-15192:
-----------------------------------------

Need to revert default value flip for semijoin conversion in HiveConf. Also, patch doesn't apply cleanly, can you rebase it?

> Use Calcite to de-correlate and plan subqueries
> -----------------------------------------------
>
>                 Key: HIVE-15192
>                 URL: https://issues.apache.org/jira/browse/HIVE-15192
>             Project: Hive
>          Issue Type: Task
>          Components: Logical Optimizer
>            Reporter: Vineet Garg
>            Assignee: Vineet Garg
>              Labels: sub-query
>         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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