keyLimit

Class: matlab.compiler.mlspark.RDD
Namespace: matlab.compiler.mlspark

Return threshold of unique keys that can be stored before spilling to disk

Syntax

result = keyLimit(obj)


Description

result = keyLimit(obj) returns the threshold of unique keys in obj that can be stored in memory before spilling to disk.

Input Arguments

obj — Input RDD

RDD object

An input RDD, specified as an RDD object.

Output Arguments

result — Threshold of unique keys

scalar value

Threshold of unique keys that can be stored before spilling to disk, returned as a scalar value.

Examples

Get Threshold of Unique Keys

Use the keyLimit method to return the threshold of unique keys that can be stored in a containers.Map object that specifies Spark™ properties. Keys that breach the threshold are spilled to disk.

%% Connect to Spark
% Change number of keys from a default threshold of 10,000 to 500
sparkProp = containers.Map( ...
    {'spark.executor.cores',...
    'spark.executor.memory',...
    'spark.executor.instances',...
    'spark.matlab.worker.numOfKeys', ...
    }, ...
    {'1',...
    '2g',...
    '1', ...
    '500'});
conf = matlab.compiler.mlspark.SparkConf('AppName','myApp', ...
                        'Master','local[1]','SparkProperties',sparkProp);
sc = matlab.compiler.mlspark.SparkContext(conf);

%% keyLimit
x = sc.parallelize({1,2,3});
x.keyLimit % ans: 500

Version History

Introduced in R2016b