Join attributes & policy
Join attributes to control and optimise performance
Stream join examples
These attributes define how the join is performed with respect to the expression, how to create the emitted event structure etc.
Attributes schema
Attribute | Description | Data Type | Required |
---|---|---|---|
expression | Simple join expression that evaluates two streams | String | |
merge events | Flag that either merge event attributes into a flattened event structure or places each event | Boolean Default: true | |
event type | User defined type of emitted event | String Default: left type - right type (i.e. typeA-typeB) | |
left / right join | See Join attribute section | Policy attribute Default |
Policy Attributes
Fine grained control can be applied to how joins are handled through the use of the policy attribute.
This becomes relevant for large and fast event stream with respect to memory and processing overhead.
Default configuration
delete on join is set to false and therefore will join events until the time to live setting is honoured.
time to live is set for 60 minutes per stored event. This is refreshed every time a new event is received with the same join attribute value.
Attributes schema
Attribute | Description | Data Type | Required |
---|---|---|---|
delete on join | Delete event from state management on a successful join | Boolean Default: false | |
time to live | Expire configuration for event stored within the state management system. Supported time units include nanoseconds, microseconds, milliseconds, seconds, hours and days | Formatted string Default: 60 minutes |
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