gszadovszky commented on code in PR #1018:
URL: https://github.com/apache/parquet-mr/pull/1018#discussion_r1064374553
##########
parquet-hadoop/src/main/java/org/apache/parquet/hadoop/ParquetFileReader.java:
##########
@@ -1038,7 +1044,9 @@ public PageReadStore readNextFilteredRowGroup() throws
IOException {
}
BlockMetaData block = blocks.get(currentBlock);
if (block.getRowCount() == 0L) {
- throw new RuntimeException("Illegal row group of 0 rows");
+ // Skip the empty block
+ advanceToNextBlock();
+ return readNextFilteredRowGroup();
Review Comment:
There is a warning log in case of `readNextRowGroup` but here we don't log
anything.
##########
parquet-hadoop/src/test/java/org/apache/parquet/hadoop/TestParquetReaderEmptyBlock.java:
##########
@@ -0,0 +1,83 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.parquet.hadoop;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.Path;
+import org.apache.parquet.column.page.PageReadStore;
+import org.apache.parquet.hadoop.metadata.ParquetMetadata;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.net.URISyntaxException;
+
+public class TestParquetReaderEmptyBlock {
+
+ private static final Path EMPTY_BLOCK_FILE_1 =
createPathFromCP("/test-empty-row-group_1.parquet");
+
+ private static final Path EMPTY_BLOCK_FILE_2 =
createPathFromCP("/test-empty-row-group_2.parquet");
+
+ private static Path createPathFromCP(String path) {
+ try {
+ return new
Path(TestParquetReaderEmptyBlock.class.getResource(path).toURI());
+ } catch (URISyntaxException e) {
+ throw new RuntimeException(e);
+ }
+ }
+
+ @Test
+ public void testReadOnlyEmptyBlock() throws IOException {
+ Configuration conf = new Configuration();
+ ParquetMetadata readFooter = ParquetFileReader.readFooter(conf,
EMPTY_BLOCK_FILE_1);
+
+ // The parquet file contains only one empty row group
+ Assert.assertEquals(1, readFooter.getBlocks().size());
+
+ // The empty block is skipped
+ try (ParquetFileReader r = new ParquetFileReader(conf, EMPTY_BLOCK_FILE_1,
readFooter)) {
+ Assert.assertNull(r.readNextRowGroup());
+ }
+ }
+
+ @Test
+ public void testSkipEmptyBlock() throws IOException {
+ Configuration conf = new Configuration();
+ ParquetMetadata readFooter = ParquetFileReader.readFooter(conf,
EMPTY_BLOCK_FILE_2);
+
+ // The parquet file contains three row groups, the second one is empty
Review Comment:
I think, it would be nice to test the case of multiple empty row groups next
to each other.
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