lidavidm commented on code in PR #14081:
URL: https://github.com/apache/arrow/pull/14081#discussion_r967105833
##########
java/adapter/jdbc/src/main/java/org/apache/arrow/adapter/jdbc/Constants.java:
##########
@@ -27,5 +27,6 @@ private Constants() {}
public static final String SQL_TABLE_NAME_KEY = "SQL_TABLE_NAME";
public static final String SQL_COLUMN_NAME_KEY = "SQL_COLUMN_NAME";
public static final String SQL_TYPE_KEY = "SQL_TYPE";
+ public static final String COMMENT = "comment";
Review Comment:
Also, since the JDBC name for this is REMARKS, should we stay consistent
with that?
##########
java/adapter/jdbc/src/test/java/org/apache/arrow/adapter/jdbc/JdbcToArrowCommentMetadataTest.java:
##########
@@ -0,0 +1,168 @@
+/*
+ * 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.arrow.adapter.jdbc;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.sql.Connection;
+import java.sql.DatabaseMetaData;
+import java.sql.DriverManager;
+import java.sql.ResultSet;
+import java.sql.ResultSetMetaData;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+
+import org.apache.arrow.memory.RootAllocator;
+import org.apache.arrow.vector.types.pojo.Schema;
+import org.apache.arrow.vector.util.ObjectMapperFactory;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import com.fasterxml.jackson.databind.ObjectWriter;
+
+public class JdbcToArrowCommentMetadataTest {
+
+ private final ObjectWriter schemaSerializer =
ObjectMapperFactory.newObjectMapper().writerWithDefaultPrettyPrinter();
+ private Connection conn = null;
+
+ /**
+ * This method creates Connection object and DB table and also populate data
into table for test.
+ *
+ * @throws SQLException on error
+ * @throws ClassNotFoundException on error
+ */
+ @Before
+ public void setUp() throws SQLException, ClassNotFoundException {
+ String url =
"jdbc:h2:mem:JdbcToArrowTest?characterEncoding=UTF-8;INIT=runscript from
'classpath:/h2/comment.sql'";
+ String driver = "org.h2.Driver";
+ Class.forName(driver);
+ conn = DriverManager.getConnection(url);
+ }
+
+ @After
+ public void tearDown() throws SQLException {
+ if (conn != null) {
+ conn.close();
+ conn = null;
+ }
+ }
+
+ @Test
+ public void schemaComment() throws Exception {
+ boolean includeMetadata = false;
+ String schemaJson =
schemaSerializer.writeValueAsString(getSchemaWithCommentFromQuery(includeMetadata));
+ String expectedSchema =
getExpectedSchema("/h2/expectedSchemaWithComments.json");
+ assertThat(schemaJson).isEqualTo(expectedSchema);
+ }
+
+ @Test
+ public void schemaCommentWithDatabaseMetadata() throws Exception {
+ boolean includeMetadata = true;
+ String schemaJson =
schemaSerializer.writeValueAsString(getSchemaWithCommentFromQuery(includeMetadata));
+ String expectedSchema =
getExpectedSchema("/h2/expectedSchemaWithCommentsAndJdbcMeta.json");
+ assertThat(schemaJson).isEqualTo(expectedSchema);
+ }
+
+ private Schema getSchemaWithCommentFromQuery(boolean includeMetadata) throws
SQLException {
+ DatabaseMetaData metaData = conn.getMetaData();
+ try (Statement statement = conn.createStatement()) {
+ try (ResultSet resultSet = statement.executeQuery("select * from
table1")) {
+ ResultSetMetaData resultSetMetaData = resultSet.getMetaData();
+ Map<Integer, String> columnCommentByColumnIndex =
getColumnComments(metaData, resultSetMetaData);
+
+ String tableName =
getTableNameFromResultSetMetaData(resultSetMetaData);
+ String tableComment = getTableComment(metaData, tableName);
+ JdbcToArrowConfig config = new JdbcToArrowConfigBuilder()
+ .setAllocator(new
RootAllocator()).setSchemaComment(tableComment)
+
.setColumnCommentByColumnIndex(columnCommentByColumnIndex).setIncludeMetadata(includeMetadata).build();
+ return JdbcToArrowUtils.jdbcToArrowSchema(resultSetMetaData, config);
Review Comment:
Ah, for the other metadata, this method automatically extracts the metadata
values and adds them here. But for REMARKS, it's non-trivial to extract it from
the result set so it probably shouldn't be done automatically.
At this point, I wonder if the API shouldn't just be: allow specifying extra
metadata to attach to the schema and to each column, instead of special casing
a single metadata value?
##########
java/adapter/jdbc/src/main/java/org/apache/arrow/adapter/jdbc/Constants.java:
##########
@@ -27,5 +27,6 @@ private Constants() {}
public static final String SQL_TABLE_NAME_KEY = "SQL_TABLE_NAME";
public static final String SQL_COLUMN_NAME_KEY = "SQL_COLUMN_NAME";
public static final String SQL_TYPE_KEY = "SQL_TYPE";
+ public static final String COMMENT = "comment";
Review Comment:
I think this should have the `SQL_` prefix (in both name and value) for
consistency with the other constants
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