lidavidm commented on code in PR #318:
URL: https://github.com/apache/arrow-cookbook/pull/318#discussion_r1300419197
##########
java/source/data.rst:
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@@ -23,6 +23,85 @@ Recipes related to compare, filtering or transforming data.
.. contents::
+Append VectorSchemaRoots
+========================
+
+In some cases, VectorSchemaRoot needs to be modeled as a container. To
accomplish
+this, you can use ``VectorSchemaRootAppender.append``. The following code
reads a
+Parquet file with three row groups, gets the three vectors separately, and then
+appends the three vectors together:
+
+.. testcode::
+
+ import java.io.IOException;
+
+ import org.apache.arrow.dataset.file.FileFormat;
+ import org.apache.arrow.dataset.file.FileSystemDatasetFactory;
+ import org.apache.arrow.dataset.jni.NativeMemoryPool;
+ import org.apache.arrow.dataset.scanner.ScanOptions;
+ import org.apache.arrow.dataset.scanner.Scanner;
+ import org.apache.arrow.dataset.source.Dataset;
+ import org.apache.arrow.dataset.source.DatasetFactory;
+ import org.apache.arrow.memory.BufferAllocator;
+ import org.apache.arrow.memory.RootAllocator;
+ import org.apache.arrow.vector.VectorSchemaRoot;
+ import org.apache.arrow.vector.ipc.ArrowReader;
+ import org.apache.arrow.vector.util.VectorSchemaRootAppender;
+
+ VectorSchemaRoot appendVectorSchemaRootAsOne(BufferAllocator allocator) {
Review Comment:
I think it would be clearer if we just constructed the vectors in-memory
instead of having to pull in dataset for this
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