Github user liancheng commented on a diff in the pull request:
https://github.com/apache/spark/pull/7154#discussion_r35197961
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/parquet/newParquet.scala ---
@@ -345,14 +345,23 @@ private[sql] class ParquetRelation2(
// Schema of the whole table, including partition columns.
var schema: StructType = _
+ // Cached leaves
+ val cachedLeaves: mutable.Map[Path, FileStatus] = new
mutable.HashMap[Path, FileStatus]()
+
/**
* Refreshes `FileStatus`es, footers, partition spec, and table schema.
*/
def refresh(): Unit = {
// Lists `FileStatus`es of all leaf nodes (files) under all base
directories.
+ // We only care about new FileStatus and updated FileStatus.
val leaves = cachedLeafStatuses().filter { f =>
- isSummaryFile(f.getPath) ||
- !(f.getPath.getName.startsWith("_") ||
f.getPath.getName.startsWith("."))
+ (isSummaryFile(f.getPath) ||
+ !(f.getPath.getName.startsWith("_") ||
f.getPath.getName.startsWith("."))) &&
+ (!cachedLeaves.contains(f.getPath) ||
+ cachedLeaves(f.getPath).getModificationTime <
f.getModificationTime)
+ }.map { f =>
+ cachedLeaves += (f.getPath -> f)
+ f
--- End diff --
Unfortunately there's still a bug here :) We also need to remove those
files that only exist in the old cache (namely removed files). This happens
when an existing directory is overwritten.
I think we can first keep both the old cache and the result of
`cachedLeafStatuses()`, then filter out updated and new files, and at last
update the old `FileStatus` cache.
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