[jira] [Updated] (TAJO-1809) Change default value of several configurations

["Jihoon Son (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/TAJO-1809?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jihoon Son updated TAJO-1809:
-----------------------------
    Attachment: TAJO-1809.patch

> Change default value of several configurations
> ----------------------------------------------
>
>                 Key: TAJO-1809
>                 URL: https://issues.apache.org/jira/browse/TAJO-1809
>             Project: Tajo
>          Issue Type: Task
>          Components: conf and scripts
>            Reporter: Jihoon Son
>            Assignee: Jihoon Son
>             Fix For: 0.11.0
>
>         Attachments: TAJO-1809.patch
>
>
> Tajo has many configurations. For the sake of user convenience, they all have some default value. Most of default values make sense, but some are not. Here is my idea.
> * Tajo can choose hash-based algorithm and disk-based algorithm according to the remaining resource and query workload. Here, users can give a hint using session variables whose name is HASH_*_SIZE_LIMIT. Their current default value is 256 MB, but it's too large thereby incurring GC so often, and even OOM sometimes.
> * Query cache should be disabled by default. It will not be commonly used.
> * Configurations for broadcast join should accept numbers in MB. 
> * Some configurations allow different unit in tajo-site.xml and session variable. This must be consistent.



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