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https://issues.apache.org/jira/browse/DRILL-4287?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15141554#comment-15141554
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ASF GitHub Bot commented on DRILL-4287:
---------------------------------------
Github user adeneche commented on a diff in the pull request:
https://github.com/apache/drill/pull/345#discussion_r52516038
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/store/parquet/ParquetGroupScan.java
---
@@ -182,10 +183,24 @@ public ParquetGroupScan( //
}
this.selectionRoot = selectionRoot;
- if (selection instanceof ParquetFileSelection) {
- final ParquetFileSelection pfs =
ParquetFileSelection.class.cast(selection);
- this.parquetTableMetadata = pfs.getParquetMetadata();
+
+ FileSelection newSelection = null;
+ if (!selection.isExpanded()) {
+ FileStatus firstPath = selection.getFirstPath(fs);
+ Path p = new Path(firstPath.getPath(), Metadata.METADATA_FILENAME);
+ if (!fs.exists(p)) { // no metadata cache
+ if (selection.checkedForDirectories() &&
selection.hasDirectories()) {
--- End diff --
This won't work if `checkedForDirectories==false`, right ?
`hasDirectories()` already uses `checkedForDirectories` internally, the
following should work:
if (selection.hasDirectories()) {
> Do lazy reading of parquet metadata cache file
> ----------------------------------------------
>
> Key: DRILL-4287
> URL: https://issues.apache.org/jira/browse/DRILL-4287
> Project: Apache Drill
> Issue Type: Bug
> Components: Query Planning & Optimization
> Affects Versions: 1.4.0
> Reporter: Aman Sinha
> Assignee: Jinfeng Ni
>
> Currently, the parquet metadata cache file is read eagerly during creation of
> the DrillTable (as part of ParquetFormatMatcher.isReadable()). This is not
> desirable from performance standpoint since there are scenarios where we want
> to do some up-front optimizations - e.g. directory-based partition pruning
> (see DRILL-2517) or potential limit 0 optimization etc. - and in such
> situations it is better to do lazy reading of the metadata cache file.
> This is a placeholder to perform such delayed reading since it is needed for
> the aforementioned optimizations.
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