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https://issues.apache.org/jira/browse/DRILL-4589?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15231195#comment-15231195
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ASF GitHub Bot commented on DRILL-4589:
---------------------------------------
Github user jinfengni commented on a diff in the pull request:
https://github.com/apache/drill/pull/468#discussion_r58953148
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/planner/DFSDirPartitionLocation.java
---
@@ -0,0 +1,70 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Class defines a single partition corresponding to a directory in a DFS
table.
+ */
+package org.apache.drill.exec.planner;
+
+
+import com.google.common.collect.Lists;
+
+import java.util.Collection;
+import java.util.List;
+
+public class DFSDirPartitionLocation implements PartitionLocation {
+ private final Collection<PartitionLocation> subPartitions;
+ private final String[] dirs;
+
+ public DFSDirPartitionLocation(String[] dirs,
Collection<PartitionLocation> subPartitions) {
+ this.subPartitions = subPartitions;
+ this.dirs = dirs;
+ }
+
+ @Override
+ public String getPartitionValue(int index) {
+ assert index < dirs.length;
+ return dirs[index];
+ }
+
+ @Override
+ public String getEntirePartitionLocation() {
+ throw new UnsupportedOperationException("Should not call
getEntirePartitionLocation for composite partition location!");
+ }
+
+ @Override
+ public List<PartitionLocation> getPartitionLocationRecursive() {
--- End diff --
I changed this method, such that now it returns list of
SimplePartitionLocation. This method would return all SimplePartitionLocation
it consists of. In your example, it would return 4 DFSFilePartitionLocations,
if it's called at the DFSDirPartitionLocation corresponding to '2016'. This
method is used when we construct a GroupScan after pruning, since only
SimplePartitionLocation keeps track the entire path, which is required by a
groupscan specification.
The file partition location keeps track of full path (which would be used
when created groupscan) and the partition keys. The dir keeps track the nested
partition, and the common partition keys.
> 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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