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Comment: fix link to DDL doc's "Create Table"

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Code Block
CREATE INDEX index_name

ON TABLE base_table_name (col_name, ...)
AS 'index.handler.class.name'
[WITH DEFERRED REBUILD]
[IDXPROPERTIES (property_name=property_value, ...)]
[IN TABLE index_table_name]
[PARTITIONED BY (col_name, ...)]
[
   [ ROW FORMAT ...] STORED AS ...
   | STORED BY ...
]
[LOCATION hdfs_path]
[TBLPROPERTIES (...)]
[COMMENT "index comment"]

For the details of the various clauses such as ROW FORMAT, see LanguageManual DDL#Create_Create Table.

By default, index partitioning matches the partitioning of the base table. The PARTITIONED BY clause may be used to specify a subset of the table's partitioning columns (this column list may be empty to indicate that the index spans all partitions of the table). For example, a table may be partitioned by date+region even though the index is partitioned by date alone (each index partition spanning all regions).

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Code Block
CREATE TABLE t(i int, j int);
CREATE INDEX x ON TABLE t(j)

AS 'org.apache.hadoop.hive.ql.index.compact.CompactIndexHandler';

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Code Block
CREATE INDEX x ON TABLE t(j)

AS 'org.apache.hadoop.hive.ql.index.compact.CompactIndexHandler'
IN TABLE t_x;

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The corresponding Java inerface is defined below, together with a companion abstract base class which handlers should extend.

Code Block

package org.apache.hadoop.hive.ql.metadata;

import java.util.List;

import org.apache.hadoop.conf.Configurable;

import org.apache.hadoop.hive.ql.plan.api.Task;

/**
 * HiveIndexHandler defines a pluggable interface for adding new
 * index handlers to Hive.
 */
public interface HiveIndexHandler extends Configurable
{
  /**
 * Determines whether this handler implements indexes by creating
 * an index table.
   *
 * @return true if index creation implies creation of an index table in Hive;
 * false if the index representation is not stored in a Hive table
   */
  boolean usesIndexTable();

  /**
 * Requests that the handler validate an index definition and
 * fill in additional information about its stored representation.
 *
  * @param baseTable the definition of the table being indexed
   *
 * @param index the definition of the index being created
   *
 * @param indexTable a partial definition of the index table to be used for
  * storing the index representation, or null if usesIndexTable() returns
  * false; the handler can augment the index's storage descriptor
 * (e.g. with information about input/output format)
  * and/or the index table's definition (typically with additional
 * columns containing the index representation, e.g. pointers into HDFS)
   *
 * @throw HiveException if the index definition is invalid with
 * respect to either the base table or the supplied index table definition
   */
  void analyzeIndexDefinition(
    org.apache.hadoop.hive.metastore.api.Table baseTable,
    org.apache.hadoop.hive.metastore.api.Index index,
    org.apache.hadoop.hive.metastore.api.Table indexTable)
      throws HiveException;

  /**
 * Requests that the handler generate a plan for building the index;
 * the plan should read the base table and write out the index representation.
   *
 * @param baseTable the definition of the table being indexed
   *
 * @param index the definition of the index
   *
 * @param partitions a list of specific partitions of the base
 * table for which the index should be built, or null if
 * an index for the entire table should be rebuilt
   *
 * @param indexTable the definition of the index table, or
 * null if usesIndexTable() returns null
   *
 * @return list of tasks to be executed in parallel for building
  * the index
   *
 * @throw HiveException if plan generation fails
   */
  List<Task<?>> generateIndexBuildTaskList(
    org.apache.hadoop.hive.metastore.api.Table baseTable,
    org.apache.hadoop.hive.metastore.api.Index index,
    List<org.apache.hadoop.hive.metastore.api.Partition> partitions,
    org.apache.hadoop.hive.metastore.api.Table indexTable)
      throws HiveException;
}

/**
 * Abstract base class for index handlers.  This is provided as insulation
 * so that as HiveIndexHandler evolves, default implementations of new
 * methods can be added here in order to avoid breaking existing
 * plugin implementations.
 */
public abstract class AbstractIndexHandler implements HiveIndexHandler
{
}

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