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The operator can save the learned tree into a database via the second output port. It continuously put out a serialized version of the tree which can be used to save it in a database, e.g. a MongoDB. When the analysis is started again, the information from the database can be used. This is useful, if a lot of knowledge is learned and if it would take a while to gain this knowledge again. On the startup, the information from the database is read a single time (if an information is available) and written into the operator. The PQL query in the codeblock shows , how to use the backup functionality.
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