Two-stage routing is available only if the number of partitions in the source and target are the same.
when you set two-stage routing the flow symbol changes from a pattern with one X in the middle to a pattern with two Xs in the middle.
use two-stage routing for all-to-all flows.
When an all to all flow connect with the layouts containing a large number of partitions, the co >operating system uses many network resources, if the number of partitions in the source and destination component is N, an all to all flow uses resources proportional to N to the 2nd power.
To save network resources, you can mark an all-to-all flow as two-stage routing, with two-stage routing, the all-to-all flow uses only 2N√N resources.
ex-> an all-to-all flow with 25 portions uses 25*25=625 resources, but with two-stage routing uses only 2*25*5=250 resources.
The source component must be one of the following to use two-stage routing -
PARTITION BY KEY
PARTITION BY RANGE
PARTITION BY ROUND-ROBIN
PARTITION BY DB2EE
PARTITION BY EXPRESSION
use two-stage routing if the all-to-all floes in a graph have more than 30 partitions.
Setting two-stage routing -
To set two-stage routing, right-click on all to all flow and select Two-stage Routing from the shortcut menu.
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