apacheGH-35916 [Java][arrow-jdbc] Add extra fields to JdbcFieldInfo (a…

…pache#37123)

### Rationale for this change

Existing info is not enough to make completely accurate conversion decisions.

### What changes are included in this PR?

Include the type name reported by the database and the max number of characters as part of the `JdbcFieldInfo`.
* Closes: apache#35916

Authored-by: Diego Fernandez <aiguo.fernandez@gmail.com>
Signed-off-by: David Li <li.davidm96@gmail.com>

java/adapter/jdbc/src/main/java/org/apache/arrow/adapter/jdbc/JdbcFieldInfo.java

@@ -17,6 +17,7 @@
 
 package org.apache.arrow.adapter.jdbc;
 
+import java.sql.ResultSet;
 import java.sql.ResultSetMetaData;
 import java.sql.SQLException;
 import java.sql.Types;
@@ -40,6 +41,8 @@ public class JdbcFieldInfo {
  private final int nullability;
  private final int precision;
  private final int scale;
+ private final String typeName;
+ private final int displaySize;
 
  /**
  * Builds a <code>JdbcFieldInfo</code> using only the {@link java.sql.Types} type. Do not use this constructor
@@ -53,12 +56,13 @@ public JdbcFieldInfo(int jdbcType) {
  Preconditions.checkArgument(
  (jdbcType != Types.DECIMAL && jdbcType != Types.NUMERIC),
  "DECIMAL and NUMERIC types require a precision and scale; please use another constructor.");
-
  this.column = 0;
  this.jdbcType = jdbcType;
  this.nullability = ResultSetMetaData.columnNullableUnknown;
  this.precision = 0;
  this.scale = 0;
+ this.typeName = "";
+ this.displaySize = 0;
  }
 
  /**
@@ -75,6 +79,8 @@ public JdbcFieldInfo(int jdbcType, int precision, int scale) {
  this.nullability = ResultSetMetaData.columnNullableUnknown;
  this.precision = precision;
  this.scale = scale;
+ this.typeName = "";
+ this.displaySize = 0;
  }
 
  /**
@@ -92,6 +98,8 @@ public JdbcFieldInfo(int jdbcType, int nullability, int precision, int scale) {
  this.nullability = nullability;
  this.precision = precision;
  this.scale = scale;
+ this.typeName = "";
+ this.displaySize = 0;
  }
 
  /**
@@ -115,6 +123,25 @@ public JdbcFieldInfo(ResultSetMetaData rsmd, int column) throws SQLException {
  this.nullability = rsmd.isNullable(column);
  this.precision = rsmd.getPrecision(column);
  this.scale = rsmd.getScale(column);
+ this.typeName = rsmd.getColumnTypeName(column);
+ this.displaySize = rsmd.getColumnDisplaySize(column);
+ }
+
+ /**
+ * Builds a <code>JdbcFieldInfo</code> from the corresponding row from a {@link java.sql.DatabaseMetaData#getColumns}
+ * ResulSet.
+ *
+ * @param rs The {@link java.sql.ResultSet} to get the field information from.
+ * @throws SQLException If the column information cannot be retrieved.
+ */
+ public JdbcFieldInfo(ResultSet rs) throws SQLException {
+ this.column = rs.getInt("ORDINAL_POSITION");
+ this.jdbcType = rs.getInt("DATA_TYPE");
+ this.nullability = rs.getInt("NULLABLE");
+ this.precision = rs.getInt("COLUMN_SIZE");
+ this.scale = rs.getInt("DECIMAL_DIGITS");
+ this.typeName = rs.getString("TYPE_NAME");
+ this.displaySize = rs.getInt("CHAR_OCTET_LENGTH");
  }
 
  /**
@@ -151,4 +178,18 @@ public int getScale() {
  public int getColumn() {
  return column;
  }
+
+ /**
+ * The type name as reported by the database.
+ */
+ public String getTypeName() {
+ return typeName;
+ }
+
+ /**
+ * The max number of characters for the column.
+ */
+ public int getDisplaySize() {
+ return displaySize;
+ }
 }

java/adapter/jdbc/src/test/java/org/apache/arrow/adapter/jdbc/ResultSetUtility.java

@@ -308,6 +308,16 @@ public int isNullable(int column) throws SQLException {
  return columns.get(column - 1).isNullable();
  }
 
+ @Override
+ public int getColumnDisplaySize(int column) throws SQLException {
+ return columns.get(column - 1).getDisplaySize();
+ }
+
+ @Override
+ public String getColumnTypeName(int column) throws SQLException {
+ return columns.get(column - 1).getTypeName();
+ }
+
  public static MockResultSetMetaData fromRows(ArrayList<MockRow> rows) throws SQLException {
  // Note: This attempts to dynamically construct ResultSetMetaData from the first row in a given result set.
  // If there are now rows, or the result set contains no columns, this cannot be dynamically generated and
@@ -334,6 +344,8 @@ public static class MockColumnMetaData {
  private int scale;
  private int nullable;
  private String label;
+ private String typeName;
+ private int displaySize;
 
 
  private MockColumnMetaData() {}
@@ -362,13 +374,23 @@ private int isNullable() {
  return nullable;
  }
 
+ private String getTypeName() {
+ return typeName;
+ }
+
+ private int getDisplaySize() {
+ return displaySize;
+ }
+
  public static MockColumnMetaData fromDataElement(MockDataElement element, int i) throws SQLException {
  return MockColumnMetaData.builder()
  .index(i)
  .sqlType(element.getSqlType())
  .precision(element.getPrecision())
  .scale(element.getScale())
  .nullable(element.isNullable())
+ .setTypeName("TYPE")
+ .setDisplaySize(420)
  .label("col_" + i)
  .build();
  }
@@ -410,6 +432,16 @@ public Builder nullable(int nullable) {
  return this;
  }
 
+ public Builder setTypeName(String typeName) {
+ this.columnMetaData.typeName = typeName;
+ return this;
+ }
+
+ public Builder setDisplaySize(int displaySize) {
+ this.columnMetaData.displaySize = displaySize;
+ return this;
+ }
+
  public MockColumnMetaData build() {
  return this.columnMetaData;
  }