Package com.illumon.iris.db.v2

Class EvenlyDividedTableMap

java.lang.Object

com.illumon.iris.db.v2.EvenlyDividedTableMap

public class EvenlyDividedTableMap
extends Object

Divide a table evenly into slices and put the slices into a TableMap. This enables the use of parallelism on a table without the full cost of a byExternal operation.

Method Summary

Modifier and Type	Method	Description
static TableMap	makeEvenlyDividedTableMap(Table table, int divisions, int minimumSize)	Divide the table into even slices, inserting the results into a TableMap.

Methods inherited from class java.lang.Object

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

Method Details

makeEvenlyDividedTableMap

public static TableMap makeEvenlyDividedTableMap(Table table, int divisions, int minimumSize)

Divide the table into even slices, inserting the results into a TableMap.

This method is intended to be used to enable parallelism by creating a TableMap without the cost of a full byExternal. It is important to note that any natural boundaries in the data are not respected, thus when doing operations in parallel and calling TransformableTableMap.merge() the result is very likely not the same as doing the operations individually. Care must be taken to preserve your desired semantics.

Parameters:

table - the table to divide

divisions - how many divisions should be created, you may want to align this value with TableMapTransformThreadPool.getTransformThreads().

minimumSize - the minimum size of each division

Returns:

a TableMap with constituents representing the slices of the original table