n8n-nodes-kv-storage
n8n community node that implements rudimentary key-value storage, stored in memory.
It is created for use-cases, when usage of Database or Redis is not desired, and StaticData or Code are not enough.
KV Storage is putting values into buckets, that we called Scopes.
Recommended n8n setup
This node should be used with EXECUTION_PROCESS=main.
You could also run it in own mode, but in then actually only EXECUTION scope will be working,
because n8n is starting each execution in separate node process and these processes neither share any data nor have IPC setup.
If you are using own process intentionally, you may consider using Redis instead of KV Storage node.
Same applies for multi-node setups: you may consider using Redis, since KV Storage does not have any backend
and stores all the data in memory of one single n8n node.
Scopes
Execution
Values, put into this scope will be readable only by the nodes within the same Workflow Execution.
Multiple Execution scopes may coexist: We differentiate between scopes of different executions by using {{ $execution.id }}
This is recommended for short-living values, like loop counters, calculating indices, or strings that need to be combined together.
Please consider keeping Expires / TTL parameter for such values, because otherwise these entries will never be deleted
and can increase memory consumption of your n8n process
Workflow
Workflow-scoped values will be accessible to every node within the same workflow (considering WorkflowID was not changed)
in every Workflow Execution.
Multiple Workflow scopes may coexist: We differentiate between scopes of different executions by using workflowId
You may use this scope to store some temporary state, that needs to be shared between different executions.
Expires / TTL parameter is enabled by default, but you may turn it off if you would not like that your values are
automatically deleted when expired.
Instance
This is global scope scope: values put here will be shared between all n8n workflows running on single n8n node.
There is only one Instance scope: we are not using any specifier.
Cluster
This scope is not implemented.
Cluster-scoped values would be accessible to every node in n8n cluster.
Node Actions
setValue
Sets value based on key, Scope (Execution/Workflow/Instance) and specifier/ID of the Scope.
Expires / TTL parameter may be used if values need to be automatically deleted after some time.
Sends added or updated events that can be listened to using KV Storage Trigger node.
incrementValue
Increments value based on key, Scope (Execution/Workflow/Instance) and specifier/ID of the Scope.
If value was not set in the past, it is initialized with 1.
Expires / TTL parameter may be used if values need to be automatically deleted after some time.
Sends added or updated events that can be listened to using KV Storage Trigger node.
getValue
Returns value, based on Scope, Scope specifier and key.
listAllScopeKeys
Returns all keys within one Scope.
listAllKeyValues
Returns all entries (key/value pairs) within one Scope.
Debug: listAllKeyValuesInAllScopes
Returns all entries (key/value pairs) within all Scope.
TTL and Value deletion
If Expires / TTL parameters were provided when value was set, these values will be automatically deleted after expiration.
Deletion job is schedules to run every 1000ms.
Deletion job sends deleted events for every key that is deleted. You can listen to this event using KV Storage Trigger node.
Trigger Node
With KV Storage Trigger node you can listen to added edited and deleted events in respective scopes.
If you select Workspace scope, you must provide workflowId (or comma-separated list of multiple workflowIds) that will be observed.
Contributions and development
To test this node on local npm installation, you can use make run command.
You can also use make prepublish target to auto-format and lint-fix your code before submitting your changes.
Please refer to Makefile.
License
This project is licensed under MIT License.