[
https://issues.apache.org/jira/browse/TAJO-744?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13995119#comment-13995119
]
Alvin Henrick commented on TAJO-744:
------------------------------------
Hi Hyunsik,
Thank you for the response. What are the use-cases when we
will need dense table ? I am storing the partition values in the respective
columns with types so that we can pass the predicates into the query to
dynamically drop the columns.
e.g. (col_name='JOIN_DATE' AND col_date > '2010-08-10') OR
(col_name='COUNTRY' AND col_text = 'US')
This will drop all the partitions where joining date in greater that 2010-08-10
and country is US and the only join_date and country will be considered when
dropping the partition because the composite count will tell us only 2 columns
are involved.
Thanks!
Warm Regards,
Alvin.
> ALTER TABLE ADD/DROP PARTITION statement
> ----------------------------------------
>
> Key: TAJO-744
> URL: https://issues.apache.org/jira/browse/TAJO-744
> Project: Tajo
> Issue Type: New Feature
> Components: catalog
> Affects Versions: 0.9.0
> Reporter: Hyunsik Choi
> Assignee: Alvin Henrick
> Fix For: 0.9.0
>
> Attachments: TAJO-744.Henrick-140423.01.patch.txt
>
>
> Currently, Tajo does not manage partitioned directly. In Tajo, each partition
> is just a directory. For each query, a logical planner traverses matched
> directories in HDFS according to partition predicates.
> This approach is not efficient especially in the environment where the number
> of partitions are very large. It also makes partition management hard.
> Tajo should manage partitions directly by using ALTER TABLE ADD/DROP
> PARTITION statements. A number of partition entries should be stored in the
> underlying database that catalog uses.
> {code:title=Synopsis of ALTER TABLE ADD/DROP PARTITION}
> ALTER TABLE table_name [IF NOT EXISTS] ADD COLUMN PARTITION (key1 = 'val2',
> key2 = 'val2', ...) WITH ('prop_key' = 'prop_val', ...) LOCATION '...';
> ALTER TABLE table_name [IF EXISTS] DROP COLUMN PARTITION (key1
> [=|<|<=|>|>=|!=] 'val1');
> {code}
--
This message was sent by Atlassian JIRA
(v6.2#6252)
