Github user ppadma commented on a diff in the pull request:
https://github.com/apache/drill/pull/653#discussion_r88770685
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/store/parquet/Metadata.java
---
@@ -495,31 +499,75 @@ private ParquetFileMetadata_v3
getParquetFileMetadata_v3(ParquetTableMetadata_v3
* @param p
* @throws IOException
*/
- private void writeFile(ParquetTableMetadata_v3 parquetTableMetadata,
Path p) throws IOException {
+ private void writeFile(ParquetTableMetadata_v3 parquetTableMetadata,
String path) throws IOException {
JsonFactory jsonFactory = new JsonFactory();
jsonFactory.configure(Feature.AUTO_CLOSE_TARGET, false);
jsonFactory.configure(JsonParser.Feature.AUTO_CLOSE_SOURCE, false);
ObjectMapper mapper = new ObjectMapper(jsonFactory);
SimpleModule module = new SimpleModule();
module.addSerializer(ColumnMetadata_v3.class, new
ColumnMetadata_v3.Serializer());
mapper.registerModule(module);
- FSDataOutputStream os = fs.create(p);
+
+ // If multiple clients are updating metadata cache file concurrently,
the cache file
+ // can get corrupted. To prevent this, write to a unique temporary
file and then do
+ // atomic rename.
+ UUID randomUUID = UUID.randomUUID();
--- End diff --
Yes, I wanted to use queryId as well. But, it is not easily accessible as
you mentioned. I made the change to use same UUID for METADATA_FILENAME and
METADATA_DIRECTORIES_FILENAME.
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