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In TQL, a query is any operations on the model instance data (or model data), which includes filtering, joining, and manipulations. Model instances are incarnations of the Models (or model definitions) through instantiation. The TQLEngine A-Stack stores the latest version of the model instance data, which is accessible to TQL Queries. See data storage for more details.

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Like conventional queries, TQL queries perform CRUD operations on data. but unlike conventional database queries, TQL queries are:

(1) Current. The TQLEngine A-Stack maintains the latest versions of any attribute values and attribute known values based on the model definitions. For example, the latest reading of a temperature sensor value. TQL queries always return those latest versions.

(2) Model-driven. Since the model definitions define the structure of the model data, the TQLEngine A-Stack constructs the database queries based on the model definition to retrieve requested data or perform other CRUD operations. The model definition is NOT the data schema. Model instance data are saved in schemaless key value pairs.

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