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 <[email protected]>
Signed-off-by: David Li <[email protected]>

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;
         }