openhab-addons/bundles/org.openhab.persistence.inmemory/README.md
J-N-K 0b6bdad557
[inmemory] Initial contribution (#15063)
This is the initial contribution of a new volatile persistence service. It does store values in memory only and can especially be used for forecasts or other data where volatile storage is sufficient.


Signed-off-by: Jan N. Klug <github@klug.nrw>
2023-06-24 11:15:09 +02:00

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# InMemory Persistence
The InMemory persistence service provides a volatile storage, i.e. it is cleared on shutdown.
Because of that the `restoreOnStartup` strategy is not supported for this service.
The main use-case is to store data that is needed during runtime, e.g. temporary storage of forecast data that is retrieved from a binding.
Since all data is stored in memory only, there is no default strategy for this service.
Unlike other persistence services, you MUST add a configuration, otherwise no data will be persisted.
To avoid excessive memory usage, it is recommended to persist only a limited number of items and use a strategy that stores only data that is actually needed.
The service has a global configuration option `maxEntries` to limit the number of datapoints per item, the default value is `512`.
When the number of datapoints is reached and a new value is persisted, the oldest (by timestamp) value will be removed.
A `maxEntries` value of `0` disables automatic purging.