Outer stream joins
Immediately pass the first event received and initialised downstream processors
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Immediately pass the first event received and initialised downstream processors
Last updated
Was this helpful?
Outer joins are different from inner joins by immediately passing the first event received on the outer stream into the processing pipeline, which can be useful for initialising downstream processors.
Any additional events that meet the join criteria are also emitted as they arrive.
It is extremely useful for ideal to prime processing.
Priming can improve performance by reducing the latency to get initial results, which are then refined or updated as more data becomes available.
This code defines a join between the sitevisits
and webpage.adclicks
streams based on customerId
.
expression
It matches all customerId
values from sitevisits
to webpage.adclicks
.
merge events Matching events are merged.
left policy
sitevisits
events expire after 30 minutes.
right policy
Matched webpage.adclicks
events are deleted after the join.
New sitevisits
events trigger with a new customerId
initial processing and subsequent matching webpage.adclicks
events continue until expiration, with cleanup after joining.