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https://issues.apache.org/jira/browse/TAJO-1493?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14736010#comment-14736010
 ] 

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

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

    https://github.com/apache/tajo/pull/624#discussion_r39001856
  
    --- Diff: 
tajo-catalog/tajo-catalog-client/src/main/java/org/apache/tajo/catalog/AbstractCatalogClient.java
 ---
    @@ -446,6 +450,52 @@ public final PartitionDescProto getPartition(final 
String databaseName, final St
       }
     
       @Override
    +  public boolean existPartitions(String databaseName, String tableName) {
    +    try {
    +      final BlockingInterface stub = getStub();
    +      final TableIdentifierProto request = 
buildTableIdentifier(databaseName, tableName);
    +      return isSuccess(stub.existPartitionsByTableName(null, request));
    --- End diff --
    
    Even through this API is checking if the table exists, it potentially 
returns unexpected exception. If you check only its success, it may return a 
wrong result.
    
    So, you should return true or false depending on only both its success and 
UNDEFINED_PARTITION_METHODS. You can find the similar code pattern from 
``existPartitionMethod`` method in this class.


> 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
>             Fix For: 0.11.0, 0.12.0
>
>         Attachments: TAJO-1493.patch, TAJO-1493_2.patch, TAJO-1493_3.patch, 
> TAJO-1493_4.patch
>
>
> 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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