Github user paul-rogers commented on a diff in the pull request:
https://github.com/apache/drill/pull/824#discussion_r115105413
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/store/parquet/Metadata.java
---
@@ -526,6 +534,48 @@ private void writeFile(ParquetTableMetadataDirs
parquetTableMetadataDirs, Path p
}
/**
+ * Serializer for ParquetPath. Writes the path relative to the root path
+ */
+ private static class ParquetPathSerializer extends
StdSerializer<ParquetPath> {
+ private final String rootPath;
+
+ ParquetPathSerializer(String rootPath) {
+ super(ParquetPath.class);
+ this.rootPath = rootPath;
+ }
+
+ @Override
+ public void serialize(ParquetPath parquetPath, JsonGenerator
jsonGenerator, SerializerProvider serializerProvider) throws IOException,
JsonGenerationException {
+
Preconditions.checkState(parquetPath.getFullPath().startsWith(rootPath),
String.format("Path %s is not a subpath of %s", parquetPath.getFullPath(),
rootPath));
+ String relativePath =
parquetPath.getFullPath().replaceFirst(rootPath, "");
--- End diff --
Java defines a Path abstraction that will compute relative paths.
An [old fashioned
way](http://stackoverflow.com/questions/204784/how-to-construct-a-relative-path-in-java-from-two-absolute-paths-or-urls):
```
String relative = new File(base).toURI().relativize(new
File(path).toURI()).getPath();
```
From the same post, the Java 7 way:
```
Path pathAbsolute = Paths.get("/var/data/stuff/xyz.dat");
Path pathBase = Paths.get("/var/data");
Path pathRelative = pathBase.relativize(pathAbsolute);
```
Hadoop's path may have something similar.
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