[jira] [Commented] (TAJO-1493) Add a method to get partition directories with filter conditions.

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TAJO-1493?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14651081#comment-14651081 ] 

ASF GitHub Bot commented on TAJO-1493:
--------------------------------------

Github user blrunner commented on the pull request:

    https://github.com/apache/tajo/pull/624#issuecomment-127042279
  
    I implemented CatalogStore::getPartitionsByDirectSql which execute a select statement to CatalogStore for searching right partition directories. But current tajo testing cluster use MemStore for default CatalogStore and I couldn't execute the select statement because MemStore just retain all catalog informations to HashMap. If you want to verify this patch, you can test as following:
    
    ```
    mvn clean install -Pparallel-test -DLOG_LEVEL=WARN -Dmaven.fork.count=2 -Dtajo.catalog.store.class=org.apache.tajo.catalog.store.DerbyStore
    ```



> Add a method to get partition directories with filter conditions.
> -----------------------------------------------------------------
>
>                 Key: TAJO-1493
>                 URL: https://issues.apache.org/jira/browse/TAJO-1493
>             Project: Tajo
>          Issue Type: Sub-task
>          Components: Catalog
>            Reporter: Jaehwa Jung
>            Assignee: Jaehwa Jung
>
> Currently, PartitionedTableRewriter take a look into partition directories for rewriting filter conditions. It get all sub directories of table path because catalog doesn’t provide partition directories. But if there are lots of sub directories on HDFS, such as, more than 10,000 directories, it might be cause overload to NameNode. Thus, CatalogStore need to provide partition directories for specified filter conditions. I designed new method to CatalogStore as follows:
> * method name: getPartitionsWithConditionFilters
> * first parameter: database name
> * second parameter: table name
> * third parameter: where clause (included target column name and partition value)
> * return values: List<org.apache.tajo.catalog.proto.CatalogProtos.TablePartitionProto>
> * description: It scan right partition directories on CatalogStore with where caluse. 
>   For examples, users set parameters as following:
> ** first parameter: default
> ** second parameter: table1
> ** third parameter: COLUMN_NAME = 'col1' AND PARTITION_VALUE = '3
> In the previous cases, this method will create select clause as follows.
> {code:xml}
> SELECT DISTINCT A.PATH
> FROM PARTITIONS A, (
>   SELECT B.PARTITION_ID
>   FROM PARTITION_KEYS B
>   WHERE B.PARTITION_ID > 0 
>   AND (
>     COLUMN_NAME = 'col1' AND PARTITION_VALUE = '3'
>   )
> ) B
> WHERE A.PARTITION_ID > 0
> AND A.TID = ${table_id}
> AND A.PARTITION_ID = B.PARTITION_ID
> {code}
> At the first time, I considered to use EvalNode instead of where clause. But I can’t use it because of recursive related problems between tajo-catalog module and tajo-plan module. So, I’ll implement utility class to convert EvalNode to SQL.



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