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ASF GitHub Bot commented on DRILL-4530: --------------------------------------- Github user jinfengni commented on a diff in the pull request: https://github.com/apache/drill/pull/519#discussion_r70514381 --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/store/parquet/ParquetGroupScan.java --- @@ -607,7 +607,14 @@ public long getRowCount() { fileSet = Sets.newHashSet(fileNames); } - if (fileNames.isEmpty()) { + List<String> finalFileNames; + if (fileSet != null) { + finalFileNames = Lists.newArrayList(fileSet); --- End diff -- Can we use fileNames only? From Line 589 / 607, seems fileSet is assigned from fileNames; seems they are same under two ELSE branches. > Improve metadata cache performance for queries with single partition > --------------------------------------------------------------------- > > Key: DRILL-4530 > URL: https://issues.apache.org/jira/browse/DRILL-4530 > Project: Apache Drill > Issue Type: Improvement > Components: Query Planning & Optimization > Affects Versions: 1.6.0 > Reporter: Aman Sinha > Assignee: Aman Sinha > Fix For: Future > > > Consider two types of queries which are run with Parquet metadata caching: > {noformat} > query 1: > SELECT col FROM `A/B/C`; > query 2: > SELECT col FROM `A` WHERE dir0 = 'B' AND dir1 = 'C'; > {noformat} > For a certain dataset, the query1 elapsed time is 1 sec whereas query2 > elapsed time is 9 sec even though both are accessing the same amount of data. > The user expectation is that they should perform roughly the same. The main > difference comes from reading the bigger metadata cache file at the root > level 'A' for query2 and then applying the partitioning filter. query1 reads > a much smaller metadata cache file at the subdirectory level. -- This message was sent by Atlassian JIRA (v6.3.4#6332)