AggregationClient (Hortonworks Data Platform Apache HBase Java API Reference)

java.lang.Object
- org.apache.hadoop.hbase.client.coprocessor.AggregationClient

All Implemented Interfaces:

Closeable, AutoCloseable
```
@InterfaceAudience.Private
public class AggregationClient
extends Object
implements Closeable
```
This client class is for invoking the aggregate functions deployed on the Region Server side via the AggregateService. This class will implement the supporting functionality for summing/processing the individual results obtained from the AggregateService for each region.
This will serve as the client side handler for invoking the aggregate functions.
- start row < end row is an essential condition (if they are not HConstants.EMPTY_BYTE_ARRAY)
- Column family can't be null. In case where multiple families are provided, an IOException will be thrown. An optional column qualifier can also be defined.
- For methods to find maximum, minimum, sum, rowcount, it returns the parameter type. For average and std, it returns a double value. For row count, it returns a long value.
  Call close() when done.

Constructor Summary

Constructors
Constructor and Description

AggregationClient(Configuration cfg)
Constructor with Conf object

Constructors
Constructor and Description
`AggregationClient(Configuration cfg)` Constructor with Conf object

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`<R,S,P extends Message,Q extends Message,T extends Message> double`	`avg(Table table, ColumnInterpreter<R,S,P,Q,T> ci, Scan scan)` This is the client side interface/handle for calling the average method for a given cf-cq combination.
`<R,S,P extends Message,Q extends Message,T extends Message> double`	`avg(TableName tableName, ColumnInterpreter<R,S,P,Q,T> ci, Scan scan)` This is the client side interface/handle for calling the average method for a given cf-cq combination.
`void`	`close()`
`<R,S,P extends Message,Q extends Message,T extends Message> R`	`max(Table table, ColumnInterpreter<R,S,P,Q,T> ci, Scan scan)` It gives the maximum value of a column for a given column family for the given range.
`<R,S,P extends Message,Q extends Message,T extends Message> R`	`max(TableName tableName, ColumnInterpreter<R,S,P,Q,T> ci, Scan scan)` It gives the maximum value of a column for a given column family for the given range.
`<R,S,P extends Message,Q extends Message,T extends Message> R`	`median(Table table, ColumnInterpreter<R,S,P,Q,T> ci, Scan scan)` This is the client side interface/handler for calling the median method for a given cf-cq combination.
`<R,S,P extends Message,Q extends Message,T extends Message> R`	`median(TableName tableName, ColumnInterpreter<R,S,P,Q,T> ci, Scan scan)` This is the client side interface/handler for calling the median method for a given cf-cq combination.
`<R,S,P extends Message,Q extends Message,T extends Message> R`	`min(Table table, ColumnInterpreter<R,S,P,Q,T> ci, Scan scan)` It gives the minimum value of a column for a given column family for the given range.
`<R,S,P extends Message,Q extends Message,T extends Message> R`	`min(TableName tableName, ColumnInterpreter<R,S,P,Q,T> ci, Scan scan)` It gives the minimum value of a column for a given column family for the given range.
`<R,S,P extends Message,Q extends Message,T extends Message> long`	`rowCount(Table table, ColumnInterpreter<R,S,P,Q,T> ci, Scan scan)` It gives the row count, by summing up the individual results obtained from regions.
`<R,S,P extends Message,Q extends Message,T extends Message> long`	`rowCount(TableName tableName, ColumnInterpreter<R,S,P,Q,T> ci, Scan scan)` It gives the row count, by summing up the individual results obtained from regions.
`<R,S,P extends Message,Q extends Message,T extends Message> double`	`std(Table table, ColumnInterpreter<R,S,P,Q,T> ci, Scan scan)` This is the client side interface/handle for calling the std method for a given cf-cq combination.
`<R,S,P extends Message,Q extends Message,T extends Message> double`	`std(TableName tableName, ColumnInterpreter<R,S,P,Q,T> ci, Scan scan)` This is the client side interface/handle for calling the std method for a given cf-cq combination.
`<R,S,P extends Message,Q extends Message,T extends Message> S`	`sum(Table table, ColumnInterpreter<R,S,P,Q,T> ci, Scan scan)` It sums up the value returned from various regions.
`<R,S,P extends Message,Q extends Message,T extends Message> S`	`sum(TableName tableName, ColumnInterpreter<R,S,P,Q,T> ci, Scan scan)` It sums up the value returned from various regions.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail
- AggregationClient
```
public AggregationClient(Configuration cfg)
```
  Constructor with Conf object
  
  Parameters:
  
  cfg -

Method Detail

close
```
public void close()
           throws IOException
```
Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException

max

public <R,S,P extends Message,Q extends Message,T extends Message> R max(TableName tableName,
                                                                         ColumnInterpreter<R,S,P,Q,T> ci,
                                                                         Scan scan)
                                                                  throws Throwable

It gives the maximum value of a column for a given column family for the given range. In case qualifier is null, a max of all values for the given family is returned.

Parameters:: tableName -; ci -; scan -
Returns:: max val
Throws:: Throwable - The caller is supposed to handle the exception as they are thrown & propagated to it.

max

public <R,S,P extends Message,Q extends Message,T extends Message> R max(Table table,
                                                                         ColumnInterpreter<R,S,P,Q,T> ci,
                                                                         Scan scan)
                                                                  throws Throwable

It gives the maximum value of a column for a given column family for the given range. In case qualifier is null, a max of all values for the given family is returned.

Parameters:: table -; ci -; scan -
Returns:: max val
Throws:: Throwable - The caller is supposed to handle the exception as they are thrown & propagated to it.

min

public <R,S,P extends Message,Q extends Message,T extends Message> R min(TableName tableName,
                                                                         ColumnInterpreter<R,S,P,Q,T> ci,
                                                                         Scan scan)
                                                                  throws Throwable

It gives the minimum value of a column for a given column family for the given range. In case qualifier is null, a min of all values for the given family is returned.

Parameters:: tableName -; ci -; scan -
Returns:: min val
Throws:: Throwable

min

public <R,S,P extends Message,Q extends Message,T extends Message> R min(Table table,
                                                                         ColumnInterpreter<R,S,P,Q,T> ci,
                                                                         Scan scan)
                                                                  throws Throwable

It gives the minimum value of a column for a given column family for the given range. In case qualifier is null, a min of all values for the given family is returned.

Parameters:: table -; ci -; scan -
Returns:: min val
Throws:: Throwable

rowCount

public <R,S,P extends Message,Q extends Message,T extends Message> long rowCount(TableName tableName,
                                                                                 ColumnInterpreter<R,S,P,Q,T> ci,
                                                                                 Scan scan)
                                                                          throws Throwable

It gives the row count, by summing up the individual results obtained from regions. In case the qualifier is null, FirstKeyValueFilter is used to optimised the operation. In case qualifier is provided, I can't use the filter as it may set the flag to skip to next row, but the value read is not of the given filter: in this case, this particular row will not be counted ==> an error.

Parameters:: tableName -; ci -; scan -
Returns:
Throws:: Throwable

rowCount

public <R,S,P extends Message,Q extends Message,T extends Message> long rowCount(Table table,
                                                                                 ColumnInterpreter<R,S,P,Q,T> ci,
                                                                                 Scan scan)
                                                                          throws Throwable

Parameters:: table -; ci -; scan -
Returns:
Throws:: Throwable

sum

public <R,S,P extends Message,Q extends Message,T extends Message> S sum(TableName tableName,
                                                                         ColumnInterpreter<R,S,P,Q,T> ci,
                                                                         Scan scan)
                                                                  throws Throwable

It sums up the value returned from various regions. In case qualifier is null, summation of all the column qualifiers in the given family is done.

Parameters:: tableName -; ci -; scan -
Returns:: sum
Throws:: Throwable

sum

public <R,S,P extends Message,Q extends Message,T extends Message> S sum(Table table, ColumnInterpreter<R,S,P,Q,T> ci, Scan scan) throws Throwable

It sums up the value returned from various regions. In case qualifier is null, summation of all the column qualifiers in the given family is done.

Parameters:

table -

ci -

scan -

Returns:

sum

Throws:

Throwable

avg

public <R,S,P extends Message,Q extends Message,T extends Message> double avg(TableName tableName, ColumnInterpreter<R,S,P,Q,T> ci, Scan scan) throws Throwable

This is the client side interface/handle for calling the average method for a given cf-cq combination. It was necessary to add one more call stack as its return type should be a decimal value, irrespective of what columninterpreter says. So, this methods collects the necessary parameters to compute the average and returs the double value.

Parameters:

tableName -

ci -

scan -

Returns:

Throws:

Throwable

avg

public <R,S,P extends Message,Q extends Message,T extends Message> double avg(Table table, ColumnInterpreter<R,S,P,Q,T> ci, Scan scan) throws Throwable

This is the client side interface/handle for calling the average method for a given cf-cq combination. It was necessary to add one more call stack as its return type should be a decimal value, irrespective of what columninterpreter says. So, this methods collects the necessary parameters to compute the average and returs the double value.

Parameters:

table -

ci -

scan -

Returns:

Throws:

Throwable

std

public <R,S,P extends Message,Q extends Message,T extends Message> double std(TableName tableName, ColumnInterpreter<R,S,P,Q,T> ci, Scan scan) throws Throwable

This is the client side interface/handle for calling the std method for a given cf-cq combination. It was necessary to add one more call stack as its return type should be a decimal value, irrespective of what columninterpreter says. So, this methods collects the necessary parameters to compute the std and returns the double value.

Parameters:

tableName -

ci -

scan -

Returns:

Throws:

Throwable

std

public <R,S,P extends Message,Q extends Message,T extends Message> double std(Table table, ColumnInterpreter<R,S,P,Q,T> ci, Scan scan) throws Throwable

This is the client side interface/handle for calling the std method for a given cf-cq combination. It was necessary to add one more call stack as its return type should be a decimal value, irrespective of what columninterpreter says. So, this methods collects the necessary parameters to compute the std and returns the double value.

Parameters:

table -

ci -

scan -

Returns:

Throws:

Throwable

median

public <R,S,P extends Message,Q extends Message,T extends Message> R median(TableName tableName, ColumnInterpreter<R,S,P,Q,T> ci, Scan scan) throws Throwable

This is the client side interface/handler for calling the median method for a given cf-cq combination. This method collects the necessary parameters to compute the median and returns the median.

Parameters:

tableName -

ci -

scan -

Returns:

R the median

Throws:

Throwable

median

public <R,S,P extends Message,Q extends Message,T extends Message> R median(Table table, ColumnInterpreter<R,S,P,Q,T> ci, Scan scan) throws Throwable

This is the client side interface/handler for calling the median method for a given cf-cq combination. This method collects the necessary parameters to compute the median and returns the median.

Parameters:

table -

ci -

scan -

Returns:

R the median

Throws:

Throwable

Class AggregationClient

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

AggregationClient

Method Detail

close

max

max

min

min

rowCount

rowCount

sum

sum

avg

avg

std

std

median

median