[GitHub] [arrow-cookbook] danepitkin commented on a diff in pull request #316: [Java] Document how to convert JDBC Adapter result into a Parquet file

["danepitkin (via GitHub)" <gi...@apache.org>]

danepitkin commented on code in PR #316:
URL: https://github.com/apache/arrow-cookbook/pull/316#discussion_r1325072073


##########
java/source/io.rst:
##########
@@ -263,6 +263,93 @@ Write - Out to Buffer
 
    Number of rows written: 3
 
+Write Parquet Files
+*******************
+
+Let's read an Arrow file and populate that data into a Parquet file.
+
+.. testcode::
+
+    import java.io.IOException;
+    import java.nio.file.DirectoryStream;
+    import java.nio.file.Files;
+    import java.nio.file.Path;
+    import java.nio.file.Paths;
+
+    import org.apache.arrow.dataset.file.DatasetFileWriter;
+    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.ipc.ArrowFileReader;
+    import org.apache.arrow.vector.ipc.ArrowReader;
+    import org.apache.arrow.vector.ipc.SeekableReadChannel;
+    import org.apache.arrow.vector.util.ByteArrayReadableSeekableByteChannel;
+
+    // read arrow demo data
+    Path uriRead = Paths.get("./thirdpartydeps/arrowfiles/random_access.arrow");

Review Comment:
   Should we add a comment describing what's in this file? Looks like it's three row groups of 3 rows each based on the output.



##########
java/source/jdbc.rst:
##########
@@ -307,3 +307,191 @@ values to the given scale.
    102    true    100000000030.0000000    some char text      [1,2]
    INT_FIELD1    BOOL_FIELD2    BIGINT_FIELD5    CHAR_FIELD16    LIST_FIELD19
    103    true    10000000003.0000000    some char text      [1]
+
+Write ResultSet to Parquet File
+===============================
+
+As an example, we are trying to write a parquet file from the JDBC adapter results.
+
+.. testcode::
+
+    import java.io.BufferedReader;
+    import java.io.FileReader;
+    import java.io.IOException;
+    import java.nio.file.DirectoryStream;
+    import java.nio.file.Files;
+    import java.nio.file.Path;
+    import java.sql.Connection;
+    import java.sql.DriverManager;
+    import java.sql.ResultSet;
+    import java.sql.SQLException;
+    import java.sql.Types;
+    import java.util.HashMap;
+
+    import org.apache.arrow.adapter.jdbc.ArrowVectorIterator;
+    import org.apache.arrow.adapter.jdbc.JdbcFieldInfo;
+    import org.apache.arrow.adapter.jdbc.JdbcToArrow;
+    import org.apache.arrow.adapter.jdbc.JdbcToArrowConfig;
+    import org.apache.arrow.adapter.jdbc.JdbcToArrowConfigBuilder;
+    import org.apache.arrow.adapter.jdbc.JdbcToArrowUtils;
+    import org.apache.arrow.dataset.file.DatasetFileWriter;
+    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.types.pojo.Schema;
+    import org.apache.ibatis.jdbc.ScriptRunner;
+    import org.slf4j.LoggerFactory;
+
+    import ch.qos.logback.classic.Level;
+    import ch.qos.logback.classic.Logger;
+
+    class JDBCReader extends ArrowReader {

Review Comment:
   Awesome!



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