drill-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Jinfeng Ni (JIRA)" <j...@apache.org>
Subject [jira] [Created] (DRILL-4589) Reduce planning time for file system partition pruning by reducing filter evaluation overhead
Date Wed, 06 Apr 2016 21:02:25 GMT
Jinfeng Ni created DRILL-4589:
---------------------------------

             Summary: Reduce planning time for file system partition pruning by reducing filter
evaluation overhead
                 Key: DRILL-4589
                 URL: https://issues.apache.org/jira/browse/DRILL-4589
             Project: Apache Drill
          Issue Type: Bug
          Components: Query Planning & Optimization
            Reporter: Jinfeng Ni


When Drill is used to query hundreds of thousands, or even millions of files organized into
multi-level directories, user typically will provide a partition filter like  : dir0 = something
and dir1 = something2 and .. .  

For such queries, we saw the query planning time could be unacceptable long, due to three
main overheads: 1) to expand and get the list of files, 2) to evaluate the partition filter,
3) to get the metadata, in the case of parquet files for which metadata cache file is not
available. 

DRILL-2517 targets at the 3rd part of overhead. As a follow-up work after DRILL-2517, we plan
to reduce the filter evaluation overhead. For now, the partition filter evaluation is applied
to file level. In many cases, we saw that the number of leaf subdirectories is significantly
lower than that of files. Since all the files under the same leaf subdirecctory share the
same directory metadata, we should apply the filter evaluation at the leaf subdirectory. By
doing that, we could reduce the cpu overhead to evaluate the filter, and the memory overhead
as well.








--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

Mime
View raw message