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https://issues.apache.org/jira/browse/DRILL-4905?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15534211#comment-15534211
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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_r81245030
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/store/parquet/ParquetGroupScan.java
---
@@ -864,6 +872,14 @@ public String getDigest() {
return toString();
}
+ public void setCacheFileRoot(String cacheFileRoot) {
+ this.cacheFileRoot = cacheFileRoot;
+ }
+
+ public void setBatchSize(long batchSize) {
+ this.recommendedBatchSize = batchSize;
--- End diff --
I feel it's fine we do not have such check. Max value for option is
checked when users tries "alter session set" command.
For "limit n" query where n is > max value, ParquetRecordReader would pick
min of two values, essentially ignore this recommendedBatchSize (?).
> 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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