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https://issues.apache.org/jira/browse/DRILL-4905?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15573624#comment-15573624
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ASF GitHub Bot commented on DRILL-4905:
---------------------------------------
Github user jinfengni commented on a diff in the pull request:
https://github.com/apache/drill/pull/597#discussion_r83335163
--- Diff:
exec/java-exec/src/test/java/org/apache/drill/exec/store/parquet/ParquetRecordReaderTest.java
---
@@ -637,7 +637,7 @@ public void testPerformance(@Injectable final
DrillbitContext bitContext,
final FileSystem fs = new CachedSingleFileSystem(fileName);
final BufferAllocator allocator = RootAllocatorFactory.newRoot(c);
for(int i = 0; i < 25; i++) {
- final ParquetRecordReader rr = new ParquetRecordReader(context,
256000, fileName, 0, fs,
+ final ParquetRecordReader rr = new ParquetRecordReader(context,
256000, -1, fileName, 0, fs,
--- End diff --
If no param for "NumRecordsToRead" means rowCount, we do not need to change
here.
> Push down the LIMIT to the parquet reader scan to limit the numbers of
> records read
> -----------------------------------------------------------------------------------
>
> Key: DRILL-4905
> URL: https://issues.apache.org/jira/browse/DRILL-4905
> Project: Apache Drill
> Issue Type: Bug
> Components: Storage - Parquet
> Affects Versions: 1.8.0
> Reporter: Padma Penumarthy
> Assignee: Padma Penumarthy
> Fix For: 1.9.0
>
>
> Limit the number of records read from disk by pushing down the limit to
> parquet reader.
> For queries like
> select * from <table> limit N;
> where N < size of Parquet row group, we are reading 32K/64k rows or entire
> row group. This needs to be optimized to read only N rows.
>
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