src/java/org/apache/hcatalog/mapreduce/HCatTableInfo.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.hcatalog.mapreduce;

import java.io.IOException;
import java.io.Serializable;

import org.apache.hadoop.hive.metastore.MetaStoreUtils;
import org.apache.hadoop.hive.metastore.api.Table;
import org.apache.hcatalog.common.HCatUtil;
import org.apache.hcatalog.data.schema.HCatSchema;

/**
 *
 * HCatTableInfo - class to communicate table information to {@link HCatInputFormat}
 * and {@link HCatOutputFormat}
 *
 */
public class HCatTableInfo implements Serializable {


    private static final long serialVersionUID = 1L;

    /** The db and table names */
    private final String databaseName;
    private final String tableName;

    /** The table schema. */
    private final HCatSchema dataColumns;
    private final HCatSchema partitionColumns;

    /** The table being written to */
    private final Table table;

    /** The storer info */
    private StorerInfo storerInfo;

    /**
     * Initializes a new HCatTableInfo instance to be used with {@link HCatInputFormat}
     * for reading data from a table.
     * work with hadoop security, the kerberos principal name of the server - else null
     * The principal name should be of the form:
     * <servicename>/_HOST@<realm> like "hcat/_HOST@myrealm.com"
     * The special string _HOST will be replaced automatically with the correct host name
     * @param databaseName the db name
     * @param tableName the table name
     * @param dataColumns schema of columns which contain data
     * @param partitionColumns schema of partition columns
     * @param storerInfo information about storage descriptor
     * @param table hive metastore table class
     */
    HCatTableInfo(
        String databaseName,
        String tableName,
        HCatSchema dataColumns,
        HCatSchema partitionColumns,
        StorerInfo storerInfo,
        Table table) {
        this.databaseName = (databaseName == null) ? MetaStoreUtils.DEFAULT_DATABASE_NAME : databaseName;
        this.tableName = tableName;
        this.dataColumns = dataColumns;
        this.table = table;
        this.storerInfo = storerInfo;
        this.partitionColumns = partitionColumns;
    }

    /**
     * Gets the value of databaseName
     * @return the databaseName
     */
    public String getDatabaseName() {
        return databaseName;
    }

    /**
     * Gets the value of tableName
     * @return the tableName
     */
    public String getTableName() {
        return tableName;
    }

    /**
     * @return return schema of data columns as defined in meta store
     */
    public HCatSchema getDataColumns() {
        return dataColumns;
    }

    /**
     * @return schema of partition columns
     */
    public HCatSchema getPartitionColumns() {
        return partitionColumns;
    }

    /**
     * @return the storerInfo
     */
    public StorerInfo getStorerInfo() {
        return storerInfo;
    }

    public String getTableLocation() {
        return table.getSd().getLocation();
    }

    /**
     * minimize dependency on hive classes so this is package private
     * this should eventually no longer be used
     * @return hive metastore representation of table
     */
    Table getTable() {
        return table;
    }

    /**
     * create an HCatTableInfo instance from the supplied Hive Table instance
     * @param table to create an instance from
     * @return HCatTableInfo
     * @throws IOException
     */
    static HCatTableInfo valueOf(Table table) throws IOException {
        // Explicitly use {@link org.apache.hadoop.hive.ql.metadata.Table} when getting the schema,
        // but store @{link org.apache.hadoop.hive.metastore.api.Table} as this class is serialized
        // into the job conf.
        org.apache.hadoop.hive.ql.metadata.Table mTable =
            new org.apache.hadoop.hive.ql.metadata.Table(table);
        HCatSchema schema = HCatUtil.extractSchema(mTable);
        StorerInfo storerInfo =
            InternalUtil.extractStorerInfo(table.getSd(), table.getParameters());
        HCatSchema partitionColumns = HCatUtil.getPartitionColumns(mTable);
        return new HCatTableInfo(table.getDbName(), table.getTableName(), schema,
            partitionColumns, storerInfo, table);
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        HCatTableInfo tableInfo = (HCatTableInfo) o;

        if (dataColumns != null ? !dataColumns.equals(tableInfo.dataColumns) : tableInfo.dataColumns != null)
            return false;
        if (databaseName != null ? !databaseName.equals(tableInfo.databaseName) : tableInfo.databaseName != null)
            return false;
        if (partitionColumns != null ? !partitionColumns.equals(tableInfo.partitionColumns) : tableInfo.partitionColumns != null)
            return false;
        if (storerInfo != null ? !storerInfo.equals(tableInfo.storerInfo) : tableInfo.storerInfo != null) return false;
        if (table != null ? !table.equals(tableInfo.table) : tableInfo.table != null) return false;
        if (tableName != null ? !tableName.equals(tableInfo.tableName) : tableInfo.tableName != null) return false;

        return true;
    }


    @Override
    public int hashCode() {
        int result = databaseName != null ? databaseName.hashCode() : 0;
        result = 31 * result + (tableName != null ? tableName.hashCode() : 0);
        result = 31 * result + (dataColumns != null ? dataColumns.hashCode() : 0);
        result = 31 * result + (partitionColumns != null ? partitionColumns.hashCode() : 0);
        result = 31 * result + (table != null ? table.hashCode() : 0);
        result = 31 * result + (storerInfo != null ? storerInfo.hashCode() : 0);
        return result;
    }

}