org.apache.hawq.pxf.plugins.hbase.utilities

Class HBaseLookupTable

java.lang.Object

org.apache.hawq.pxf.plugins.hbase.utilities.HBaseLookupTable

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

public class HBaseLookupTable
extends java.lang.Object
implements java.io.Closeable

HBaseLookupTable will load a table's lookup information from HBase pxflookup table if exists.
This table holds mappings between HAWQ column names (key) and HBase column names (value).
E.g. for an HBase table "hbase_table", mappings between HAWQ column names and HBase column names, when "hawq1" is mapped to "cf1:hbase1" and "hawq2" is mapped to "cf1:hbase2", will be:

        ROW                     COLUMN+CELL
  hbase_table             column=mapping:hawq1, value=cf1:hbase1
  hbase_table             column=mapping:hawq2, value=cf1:hbase2
 

Data is returned as a map of string and byte array from getMappings(String).

Once created, close() MUST be called to cleanup resources.

Constructor Summary

Constructors

Constructor and Description
HBaseLookupTable(org.apache.hadoop.conf.Configuration conf) Constructs a connector to HBase lookup table.

Method Summary

Modifier and Type	Method and Description
void	close() Closes HBase resources.
java.util.Map<java.lang.String,byte[]>	getMappings(java.lang.String tableName) Returns mappings for given table name between its HAWQ column names and HBase column names.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

HBaseLookupTable

public HBaseLookupTable(org.apache.hadoop.conf.Configuration conf)
                 throws java.lang.Exception

Constructs a connector to HBase lookup table. Requires calling close() to close HBaseAdmin instance.

Parameters:

conf - HBase configuration

Throws:

java.io.IOException - when initializing HBaseAdmin fails

java.lang.Exception

Method Detail

getMappings

public java.util.Map<java.lang.String,byte[]> getMappings(java.lang.String tableName)
                                                   throws java.io.IOException

Returns mappings for given table name between its HAWQ column names and HBase column names. If lookup table doesn't exist or no mappings for the table exist, returns null.

All HAWQ column names are returns in low case.

Parameters:

tableName - HBase table name

Returns:

mappings between HAWQ column names and HBase column names

Throws:

java.io.IOException - when HBase operations fail

close

public void close()
           throws java.io.IOException

Closes HBase resources. Must be called after initializing this class.

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable

Throws:

java.io.IOException