FetchData (RRD4J 2.2.1 API)

java.lang.Object
- org.rrd4j.core.FetchData

```
public class FetchData
extends Object
```
Class used to represent data fetched from the RRD. Object of this class is created when the method fetchData() is called on a FetchRequest object.
Data returned from the RRD is, simply, just one big table filled with timestamps and corresponding datasource values. Use getRowCount() method to count the number of returned timestamps (table rows).
The first table column is filled with timestamps. Time intervals between consecutive timestamps are guaranteed to be equal. Use getTimestamps() method to get an array of timestamps returned.
Remaining columns are filled with datasource values for the whole timestamp range, on a column-per-datasource basis. Use getColumnCount() to find the number of datasources and getValues(i) method to obtain all values for the i-th datasource. Returned datasource values correspond to the values returned with getTimestamps() method.

Author:

Sasa Markovic

Method Summary

Methods
Modifier and Type	Method and Description
`String`	`dump()` Dumps the content of the whole FetchData object.
`String`	`exportXml()` Dumps fetch data in XML format.
`void`	`exportXml(OutputStream outputStream)` Dumps fetch data to output stream in XML format.
`void`	`exportXml(String filepath)` Dumps fetch data to file in XML format.
`double`	`get95Percentile(String dsName)` Used by ISPs which charge for bandwidth utilization on a "95th percentile" basis.
`double`	`getAggregate(String dsName, ConsolFun consolFun)` Returns single aggregated value from the fetched data for a single datasource.
`Aggregates`	`getAggregates(String dsName)` Returns all aggregated values (MIN, MAX, LAST, FIRST, AVERAGE or TOTAL) calculated from the fetched data for a single datasource.
`long`	`getArcEndTime()` Returns the timestamp of the last populated slot in the corresponding RRA archive
`long`	`getArcStep()` Returns the step of the corresponding RRA archive
`int`	`getColumnCount()` Returns the number of columns fetched from the corresponding RRD.
`int`	`getDsIndex(String dsName)` Retrieve the table index number of a datasource by name.
`String[]`	`getDsNames()` Returns array of datasource names found in the corresponding RRD.
`long`	`getFirstTimestamp()` Returns the first timestamp in this FetchData object.
`long`	`getLastTimestamp()` Returns the last timestamp in this FecthData object.
`Archive`	`getMatchingArchive()` Returns Archive object which is determined to be the best match for the timestamps specified in the fetch request.
`FetchRequest`	`getRequest()` Returns `FetchRequest` object used to create this FetchData object.
`int`	`getRowCount()` Returns the number of rows fetched from the corresponding RRD.
`double`	`getRpn95Percentile(String rpnExpression)` Same as `get95Percentile(String)`, but for a set of values calculated with the given RPN expression.
`double`	`getRpnAggregate(String rpnExpression, ConsolFun consolFun)` Returns aggregated value for a set of values calculated by applying an RPN expression to the fetched data.
`Aggregates`	`getRpnAggregates(String rpnExpression)` Returns all aggregated values for a set of values calculated by applying an RPN expression to the fetched data.
`double[]`	`getRpnValues(String rpnExpression)` Returns a set of values created by applying RPN expression to the fetched data.
`long`	`getStep()` Returns the step with which this data was fetched.
`long[]`	`getTimestamps()` Returns an array of timestamps covering the whole range specified in the `FetchReguest` object.
`double[][]`	`getValues()` Returns all archived values for all datasources.
`double[]`	`getValues(int dsIndex)` Returns all archived values for a single datasource.
`double[]`	`getValues(String dsName)` Returns all archived values for a single datasource.
`String`	`toString()` Returns string representing fetched data in a RRDTool-like form.

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

- Method Detail
  - getRowCount
```
public int getRowCount()
```
    Returns the number of rows fetched from the corresponding RRD. Each row represents datasource values for the specific timestamp.
    
    Returns:
    Number of rows.
  - getColumnCount
```
public int getColumnCount()
```
    Returns the number of columns fetched from the corresponding RRD. This number is always equal to the number of datasources defined in the RRD. Each column represents values of a single datasource.
    
    Returns:
    Number of columns (datasources).
  - getTimestamps
```
public long[] getTimestamps()
```
    Returns an array of timestamps covering the whole range specified in the FetchReguest object.
    
    Returns:
    Array of equidistant timestamps.
  - getStep
```
public long getStep()
```
    Returns the step with which this data was fetched.
    
    Returns:
    Step as long.
  - getValues
```
public double[] getValues(int dsIndex)
```
    Returns all archived values for a single datasource. Returned values correspond to timestamps returned with getTimestamps() method.
    
    Parameters:
    dsIndex - Datasource index.
    
    Returns:
    Array of single datasource values.
  - getValues
```
public double[][] getValues()
```
    Returns all archived values for all datasources. Returned values correspond to timestamps returned with getTimestamps() method.
    
    Returns:
    Two-dimensional aray of all datasource values.
  - getValues
```
public double[] getValues(String dsName)
```
    Returns all archived values for a single datasource. Returned values correspond to timestamps returned with getTimestamps() method.
    
    Parameters:
    dsName - Datasource name.
    
    Returns:
    Array of single datasource values.
  - getRpnValues
```
public double[] getRpnValues(String rpnExpression)
```
    Returns a set of values created by applying RPN expression to the fetched data. For example, if you have two datasources named x and y in this FetchData and you want to calculate values for (x+y)/2 use something like:
    getRpnValues("x,y,+,2,/");
    
    Parameters:
    rpnExpression - RRDTool-like RPN expression
    
    Returns:
    Calculated values
    
    Throws:
    
    IllegalArgumentException - Thrown if invalid RPN expression is supplied
  - getRequest
```
public FetchRequest getRequest()
```
    Returns FetchRequest object used to create this FetchData object.
    
    Returns:
    Fetch request object.
  - getFirstTimestamp
```
public long getFirstTimestamp()
```
    Returns the first timestamp in this FetchData object.
    
    Returns:
    The smallest timestamp.
  - getLastTimestamp
```
public long getLastTimestamp()
```
    Returns the last timestamp in this FecthData object.
    
    Returns:
    The biggest timestamp.
  - getMatchingArchive
```
public Archive getMatchingArchive()
```
    Returns Archive object which is determined to be the best match for the timestamps specified in the fetch request. All datasource values are obtained from round robin archives belonging to this archive.
    
    Returns:
    Matching archive.
  - getDsNames
```
public String[] getDsNames()
```
    Returns array of datasource names found in the corresponding RRD. If the request was filtered (data was fetched only for selected datasources), only datasources selected for fetching are returned.
    
    Returns:
    Array of datasource names.
  - getDsIndex
```
public int getDsIndex(String dsName)
```
    Retrieve the table index number of a datasource by name. Names are case sensitive.
    
    Parameters:
    dsName - Name of the datasource for which to find the index.
    
    Returns:
    Index number of the datasources in the value table.
  - dump
```
public String dump()
```
    Dumps the content of the whole FetchData object. Useful for debugging.
    
    Returns:
    a String object.
  - toString
```
public String toString()
```
    Returns string representing fetched data in a RRDTool-like form.
    
    Overrides:
    
    toString in class Object
    
    Returns:
    Fetched data as a string in a rrdfetch-like output form.
  - getAggregate
```
public double getAggregate(String dsName,
                  ConsolFun consolFun)
```
    Returns single aggregated value from the fetched data for a single datasource.
    
    Parameters:
    dsName - Datasource name
    consolFun - Consolidation function to be applied to fetched datasource values. Valid consolidation functions are "MIN", "MAX", "LAST", "FIRST", "AVERAGE" and "TOTAL" (these string constants are conveniently defined in the ConsolFun class)
    
    Returns:
    a double.
    
    Throws:
    
    IllegalArgumentException - Thrown if the given datasource name cannot be found in fetched data.
  - getRpnAggregate
```
public double getRpnAggregate(String rpnExpression,
                     ConsolFun consolFun)
```
    Returns aggregated value for a set of values calculated by applying an RPN expression to the fetched data. For example, if you have two datasources named x and y in this FetchData and you want to calculate MAX value of (x+y)/2 use something like:
    getRpnAggregate("x,y,+,2,/", "MAX");
    
    Parameters:
    rpnExpression - RRDTool-like RPN expression
    consolFun - Consolidation function (MIN, MAX, LAST, FIRST, AVERAGE or TOTAL)
    
    Returns:
    Aggregated value
    
    Throws:
    
    IllegalArgumentException - Thrown if invalid RPN expression is supplied
  - getAggregates
```
public Aggregates getAggregates(String dsName)
```
    Returns all aggregated values (MIN, MAX, LAST, FIRST, AVERAGE or TOTAL) calculated from the fetched data for a single datasource.
    
    Parameters:
    dsName - Datasource name.
    
    Returns:
    Simple object containing all aggregated values.
    
    Throws:
    
    IllegalArgumentException - Thrown if the given datasource name cannot be found in the fetched data.
  - getRpnAggregates
```
public Aggregates getRpnAggregates(String rpnExpression)
                            throws IOException
```
    Returns all aggregated values for a set of values calculated by applying an RPN expression to the fetched data. For example, if you have two datasources named x and y in this FetchData and you want to calculate MIN, MAX, LAST, FIRST, AVERAGE and TOTAL value of (x+y)/2 use something like:
    getRpnAggregates("x,y,+,2,/");
    
    Parameters:
    rpnExpression - RRDTool-like RPN expression
    
    Returns:
    Object containing all aggregated values
    
    Throws:
    
    IllegalArgumentException - Thrown if invalid RPN expression is supplied
    
    IOException - if any.
  - get95Percentile
```
public double get95Percentile(String dsName)
```
    Used by ISPs which charge for bandwidth utilization on a "95th percentile" basis.
    The 95th percentile is the highest source value left when the top 5% of a numerically sorted set of source data is discarded. It is used as a measure of the peak value used when one discounts a fair amount for transitory spikes. This makes it markedly different from the average.
    Read more about this topic at:
    Rednet or
    Bytemark.
    
    Parameters:
    dsName - Datasource name
    
    Returns:
    95th percentile of fetched source values
    
    Throws:
    
    IllegalArgumentException - Thrown if invalid source name is supplied
  - getRpn95Percentile
```
public double getRpn95Percentile(String rpnExpression)
```
    Same as get95Percentile(String), but for a set of values calculated with the given RPN expression.
    
    Parameters:
    rpnExpression - RRDTool-like RPN expression
    
    Returns:
    95-percentile
    
    Throws:
    
    IllegalArgumentException - Thrown if invalid RPN expression is supplied
  - exportXml
```
public void exportXml(OutputStream outputStream)
               throws IOException
```
    Dumps fetch data to output stream in XML format.
    
    Parameters:
    outputStream - Output stream to dump fetch data to
    
    Throws:
    
    IOException - Thrown in case of I/O error
  - exportXml
```
public void exportXml(String filepath)
               throws IOException
```
    Dumps fetch data to file in XML format.
    
    Parameters:
    filepath - Path to destination file
    
    Throws:
    
    IOException - Thrown in case of I/O error
  - exportXml
```
public String exportXml()
                 throws IOException
```
    Dumps fetch data in XML format.
    
    Returns:
    String containing XML formatted fetch data
    
    Throws:
    
    IOException - Thrown in case of I/O error
  - getArcStep
```
public long getArcStep()
```
    Returns the step of the corresponding RRA archive
    
    Returns:
    Archive step in seconds
  - getArcEndTime
```
public long getArcEndTime()
```
    Returns the timestamp of the last populated slot in the corresponding RRA archive
    
    Returns:
    Timestamp in seconds

Class FetchData

Method Summary

Methods inherited from class java.lang.Object

Method Detail

getRowCount

getColumnCount

getTimestamps

getStep

getValues

getValues

getValues

getRpnValues

getRequest

getFirstTimestamp

getLastTimestamp

getMatchingArchive

getDsNames

getDsIndex

dump

toString

getAggregate

getRpnAggregate

getAggregates

getRpnAggregates

get95Percentile

getRpn95Percentile

exportXml

exportXml

exportXml

getArcStep

getArcEndTime