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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-3089) Create a volume chooser that makes decisions based on table attributes
Date Fri, 26 Sep 2014 12:03:34 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-3089?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14149071#comment-14149071
] 

ASF GitHub Bot commented on ACCUMULO-3089:
------------------------------------------

Github user ctubbsii commented on a diff in the pull request:

    https://github.com/apache/accumulo/pull/16#discussion_r18085325
  
    --- Diff: core/src/main/java/org/apache/accumulo/core/client/admin/TableOperations.java
---
    @@ -103,6 +103,25 @@
       void create(String tableName, boolean versioningIter, TimeType timeType) throws AccumuloException,
AccumuloSecurityException, TableExistsException;
     
       /**
    +   * @param tableName
    +   *          the name of the table
    +   * @param limitVersion
    +   *          Enables/disables the versioning iterator, which will limit the number of
Key versions kept.
    +   * @param timeType
    +   *          specifies logical or real-time based time recording for entries in the
table
    +   * @param properties
    +   *          initial table properties the user wants
    +   * @throws AccumuloException
    +   *           if a general error occurs
    +   * @throws AccumuloSecurityException
    +   *           if the user does not have permission
    +   * @throws TableExistsException
    +   *           if the table already exists
    +   */
    +  void create(String tableName, boolean limitVersion, TimeType timeType, Map<String,String>
properties) throws AccumuloException, AccumuloSecurityException,
    --- End diff --
    
    The problem is that volumes are chosen once per tablet. So, if you are using the GeneralVolumeChooser
provided (which is really a per-table volume chooser), there is no ability to set the chooser
for this specific table until after the default one (the RandomVolumeChooser) has already
made a permanent decision for the default tablet. So, one could never write a volume chooser
that said "*Only* use this specific volume for this table." So, this feature is absolutely
essential if you want to implement a per-table volume chooser. I suppose it could be extracted
as a separate issue, which is an explicit prerequisite of this one, though.


> Create a volume chooser that makes decisions based on table attributes
> ----------------------------------------------------------------------
>
>                 Key: ACCUMULO-3089
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-3089
>             Project: Accumulo
>          Issue Type: Improvement
>            Reporter: Christopher Tubbs
>            Assignee: Jenna Huston
>
> Use case:
> User provisions multiple volumes, some with tmpfs drives, some with SSDs, some with traditional
magnetic spindle hard drives. A volume chooser could use attribute information on tables (ACCUMULO-2841)
to decide which volume to choose when creating new tablets.



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