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Difference between "Datetime", "event_time" and "store_time"

What is the difference between Datetime, event_time and store_time?

Datetime is the time that the telemetry reading was taken. This field is optional and can have different names depending on the plugin being used, but the concept is the same. A great example of this is reading historical values from a database: All the reading are captured with the same event_time (that is, when the data was captured by the agent), but the Datetime will vary for each row allowing us to see when the reading was actually taken.

event_time is the timestamp that the Ardexa Agent picked up the given message. To put it another way, it is when it entered the Ardexa platform. event_time is present for all records in the Ardexa system.

store_time is when the record is written to the hub's data store. Generally, while the edge node is online and connected, this time will usually be within one second of the event_time. However, if the node is offline for any reason, such as an internet outage, or the hub is offline for maintenance, then the store_time could be hours or days later.

In summary:

Datetime

  • Is when the device being monitored took a reading.

  • Therefore, where available, Datetime is the actual point in time when the measurement was taken.

  • Is optional.

  • Can be sourced from either your infrastructure hardware or by the Ardexa Device.

  • Users have control how it is established.

  • It's use is encouraged, i.e. we suggest you collected this value.

event_time

  • Is when the Ardexa Agent picked up that reading for transmission to the cloud. Hence, it is the time when the record entered the Ardexa system.

  • event_time is established by the Ardexa Device's local time.

  • Users have no ability to change how this is collected.

store_time

  • Is when the Ardexa Hub logged the reading to the data store. Hence, it is the time when the record was available to search.

  • store_time is established by the Ardexa Hub's local time, which is always UTC.

  • Users have no ability to change how this is collected.

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