JdbcColumn.java

/**
 * 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.hadoop.hive.jdbc;

import java.sql.SQLException;
import java.sql.Types;

/**
 * Column metadata.
 */
public class JdbcColumn {
  private final String columnName;
  private final String tableName;
  private final String tableCatalog;
  private final String type;
  private final String comment;
  private final int ordinalPos;

  JdbcColumn(String columnName, String tableName, String tableCatalog
          , String type, String comment, int ordinalPos) {
    this.columnName = columnName;
    this.tableName = tableName;
    this.tableCatalog = tableCatalog;
    this.type = type;
    this.comment = comment;
    this.ordinalPos = ordinalPos;
  }

  public String getColumnName() {
    return columnName;
  }

  public String getTableName() {
    return tableName;
  }

  public String getTableCatalog() {
    return tableCatalog;
  }

  public String getType() {
    return type;
  }

  public Integer getSqlType() throws SQLException {
    return Utils.hiveTypeToSqlType(type);
  }

  static int columnDisplaySize(int columnType) throws SQLException {
    // according to hiveTypeToSqlType possible options are:
    switch(columnType) {
    case Types.BOOLEAN:
      return columnPrecision(columnType);
    case Types.VARCHAR:
      return Integer.MAX_VALUE; // hive has no max limit for strings
    case Types.TINYINT:
    case Types.SMALLINT:
    case Types.INTEGER:
    case Types.BIGINT:
      return columnPrecision(columnType) + 1; // allow +/-

    // see http://download.oracle.com/javase/6/docs/api/constant-values.html#java.lang.Float.MAX_EXPONENT
    case Types.FLOAT:
      return 24; // e.g. -(17#).e-###
    // see http://download.oracle.com/javase/6/docs/api/constant-values.html#java.lang.Double.MAX_EXPONENT
    case Types.DOUBLE:
      return 25; // e.g. -(17#).e-####
    default:
      throw new SQLException("Invalid column type: " + columnType);
    }
  }

  static int columnPrecision(int columnType) throws SQLException {
    // according to hiveTypeToSqlType possible options are:
    switch(columnType) {
    case Types.BOOLEAN:
      return 1;
    case Types.VARCHAR:
      return Integer.MAX_VALUE; // hive has no max limit for strings
    case Types.TINYINT:
      return 3;
    case Types.SMALLINT:
      return 5;
    case Types.INTEGER:
      return 10;
    case Types.BIGINT:
      return 19;
    case Types.FLOAT:
      return 7;
    case Types.DOUBLE:
      return 15;
    default:
      throw new SQLException("Invalid column type: " + columnType);
    }
  }

  static int columnScale(int columnType) throws SQLException {
    // according to hiveTypeToSqlType possible options are:
    switch(columnType) {
    case Types.BOOLEAN:
    case Types.VARCHAR:
    case Types.TINYINT:
    case Types.SMALLINT:
    case Types.INTEGER:
    case Types.BIGINT:
      return 0;
    case Types.FLOAT:
      return 7;
    case Types.DOUBLE:
      return 15;
    default:
      throw new SQLException("Invalid column type: " + columnType);
    }
  }

  public Integer getColumnSize() throws SQLException {
    int precision = columnPrecision(Utils.hiveTypeToSqlType(type));

    return precision == 0 ? null : precision;
  }

  public Integer getDecimalDigits() throws SQLException {
    return columnScale(Utils.hiveTypeToSqlType(type));
  }

  public Integer getNumPrecRadix() {
    if (type.equalsIgnoreCase("tinyint")) {
      return 10;
    } else if (type.equalsIgnoreCase("smallint")) {
      return 10;
    } else if (type.equalsIgnoreCase("int")) {
      return 10;
    } else if (type.equalsIgnoreCase("bigint")) {
      return 10;
    } else if (type.equalsIgnoreCase("float")) {
      return 2;
    } else if (type.equalsIgnoreCase("double")) {
      return 2;
    } else { // anything else including boolean and string is null
      return null;
    }
  }

  public String getComment() {
    return comment;
  }

  public int getOrdinalPos() {
    return ordinalPos;
  }
}