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https://issues.apache.org/jira/browse/DRILL-4905?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15534172#comment-15534172
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ASF GitHub Bot commented on DRILL-4905:
---------------------------------------
Github user gparai commented on a diff in the pull request:
https://github.com/apache/drill/pull/597#discussion_r81242837
--- 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 --
This will check against the current value of the option rather than the max
value? I thought we want to ensure never to exceed the MAX value of
PARQUET_READER_RECORD_BATCH_SIZE - did I misunderstand? I looked into the code
and it seems like we don't have access to the max value - we would need to add
new methods to expose the same OR maybe invoke the validate method?
> 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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