Database Reference
In-Depth Information
Fields grouping
In this grouping, we specify two parameters—the source of the stream and the fields. The
values of the fields are actually used to control the routing of the tuples to various bolts.
This grouping guarantees that for the same field's value, the tuple will always be routed to
the same instance of the bolt.
In the following figure, field grouping is depicted between
Bolt A
and
Bolt B
, and each of
these bolts have two instances each. Notice the flow of events based on the value of the
field grouping parameter.
All the events from
Instance 1
and
Instance 2
of
Bolt A
, where the value of
Field
is
P
are
sent to
Instance 1
of
Bolt B
.
All the events from
Instance 1
and
Instance 2
of
Bolt A
, where the value of
Field
is
Q
are
sent to
Instance 2
of
Bolt B
.
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