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https://issues.apache.org/jira/browse/DRILL-4589?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15230778#comment-15230778
]
ASF GitHub Bot commented on DRILL-4589:
---------------------------------------
Github user amansinha100 commented on a diff in the pull request:
https://github.com/apache/drill/pull/468#discussion_r58921685
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/planner/FileSystemPartitionDescriptor.java
---
@@ -148,13 +139,41 @@ public String getName(int index) {
return partitionLabel + index;
}
- private String getBaseTableLocation() {
+ protected String getBaseTableLocation() {
final FormatSelection origSelection = (FormatSelection)
table.getSelection();
return origSelection.getSelection().selectionRoot;
}
@Override
protected void createPartitionSublists() {
+ final Collection<String> fileLocations = getFileLocations();
+ List<PartitionLocation> locations = new LinkedList<>();
+
+ final String selectionRoot = getBaseTableLocation();
+
+ HashMap<List<String>, List<PartitionLocation>> dirToFileMap = new
HashMap<>();
--- End diff --
Can you add a comment here with an example <key, value> pair ?
> 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
> Assignee: 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.
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