org.apache.metamodel.hbase

Class HBaseDataContext

java.lang.Object

org.apache.metamodel.AbstractDataContext

org.apache.metamodel.QueryPostprocessDataContext

org.apache.metamodel.hbase.HBaseDataContext

All Implemented Interfaces:

HasReadTypeConverters, DataContext

public class HBaseDataContext
extends QueryPostprocessDataContext

MetaModel adaptor for Apache HBase.

Field Summary

Fields

Modifier and Type	Field and Description
static String	FIELD_ID

Fields inherited from class org.apache.metamodel.QueryPostprocessDataContext

INFORMATION_SCHEMA_NAME

Constructor Summary

Constructors

Constructor and Description
HBaseDataContext(HBaseConfiguration configuration) Creates a HBaseDataContext.
HBaseDataContext(HBaseConfiguration configuration, org.apache.hadoop.hbase.client.Connection connection) Creates a HBaseDataContext.

Method Summary

Modifier and Type	Method and Description
protected Number	executeCountQuery(Table table, List<FilterItem> whereItems, boolean functionApproximationAllowed) Executes a simple count query, if possible.
protected Row	executePrimaryKeyLookupQuery(Table table, List<SelectItem> selectItems, Column primaryKeyColumn, Object keyValue) Executes a query which obtains a row by primary key (as defined by Column.isPrimaryKey()).
org.apache.hadoop.hbase.client.Admin	getAdmin() Gets the Admin used by this DataContext
HBaseConfiguration	getConfiguration() Gets the HBaseConfiguration that is used in this datacontext.
org.apache.hadoop.hbase.client.Connection	getConnection()
protected org.apache.hadoop.hbase.client.Table	getHTable(String name)
protected Schema	getMainSchema()
protected String	getMainSchemaName()
protected DataSet	materializeMainSchemaTable(Table table, Column[] columns, int maxRows) Executes a simple one-table query against a table in the main schema of the subclasses of this class.

Methods inherited from class org.apache.metamodel.QueryPostprocessDataContext

addConverter, executeQuery, getDefaultSchemaName, getMainSchemaInternal, getSchemaByNameInternal, getSchemaNamesInternal, isMainSchemaTable, isScalarFunctionMaterialized, materializeFromItem, materializeMainSchemaTable, materializeMainSchemaTable, materializeMainSchemaTable, materializeTable, materializeTable

Methods inherited from class org.apache.metamodel.AbstractDataContext

compileQuery, executeQuery, executeQuery, getColumnByQualifiedLabel, getDefaultSchema, getSchemaByName, getSchemaNames, getSchemas, getTableByQualifiedLabel, isQualifiedPathDelim, onSchemaCacheRefreshed, parseQuery, query, refreshSchemas

Methods inherited from class java.lang.Object

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

Field Detail

FIELD_ID

public static final String FIELD_ID

See Also:

Constant Field Values

Constructor Detail

HBaseDataContext

public HBaseDataContext(HBaseConfiguration configuration)

Creates a HBaseDataContext.

Parameters:

configuration -

HBaseDataContext

public HBaseDataContext(HBaseConfiguration configuration,
                        org.apache.hadoop.hbase.client.Connection connection)

Creates a HBaseDataContext.

Parameters:

configuration -

connection -

Method Detail

getAdmin

public org.apache.hadoop.hbase.client.Admin getAdmin()

Gets the Admin used by this DataContext

Returns:

getConnection

public org.apache.hadoop.hbase.client.Connection getConnection()

getMainSchema

protected Schema getMainSchema()
                        throws MetaModelException

Specified by:

getMainSchema in class QueryPostprocessDataContext

Returns:

the main schema that subclasses of this class produce

Throws:

MetaModelException

getConfiguration

public HBaseConfiguration getConfiguration()

Gets the HBaseConfiguration that is used in this datacontext.

Returns:

getMainSchemaName

protected String getMainSchemaName()
                            throws MetaModelException

Specified by:

getMainSchemaName in class QueryPostprocessDataContext

Returns:

the name of the main schema that subclasses of this class produce

Throws:

MetaModelException

executeCountQuery

protected Number executeCountQuery(Table table,
                                   List<FilterItem> whereItems,
                                   boolean functionApproximationAllowed)

Description copied from class: QueryPostprocessDataContext

Executes a simple count query, if possible. This method is provided to allow subclasses to optimize count queries since they are quite common and often a datastore can retrieve the count using some specialized means which is much more performant than counting all records manually.

Overrides:

executeCountQuery in class QueryPostprocessDataContext

Parameters:

table - the table on which the count is requested.

whereItems - a (sometimes empty) list of WHERE items.

functionApproximationAllowed - whether approximation is allowed or not.

Returns:

the count of the particular table, or null if not available.

getHTable

protected org.apache.hadoop.hbase.client.Table getHTable(String name)

executePrimaryKeyLookupQuery

protected Row executePrimaryKeyLookupQuery(Table table,
                                           List<SelectItem> selectItems,
                                           Column primaryKeyColumn,
                                           Object keyValue)

Description copied from class: QueryPostprocessDataContext

Executes a query which obtains a row by primary key (as defined by Column.isPrimaryKey()). This method is provided to allow subclasses to optimize lookup queries since they are quite common and often a datastore can retrieve the row using some specialized means which is much more performant than scanning all records manually.

Overrides:

executePrimaryKeyLookupQuery in class QueryPostprocessDataContext

Parameters:

table - the table on which the lookup is requested.

selectItems - the items to select from the lookup query.

primaryKeyColumn - the column that is the primary key

keyValue - the primary key value that is specified in the lookup query.

Returns:

the row if the particular table, or null if not available.

materializeMainSchemaTable

protected DataSet materializeMainSchemaTable(Table table,
                                             Column[] columns,
                                             int maxRows)

Description copied from class: QueryPostprocessDataContext

Executes a simple one-table query against a table in the main schema of the subclasses of this class.

Specified by:

materializeMainSchemaTable in class QueryPostprocessDataContext

Parameters:

table - the table to query

columns - the columns of the table to query

maxRows - the maximum amount of rows needed or -1 if all rows are wanted.

Returns:

a dataset with the raw table/column content.