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execute(map, query_meta, arg, params, opts)

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Executes a previously prepared query.

It must return a tuple containing the number of entries and the result set as a list of lists. The result set may also be nil if a particular operation does not support them.

The meta field is a map containing some of the fields found in the Ecto.Query struct.

It receives a process function that should be invoked for each selected field in the query result in order to convert them to the expected Ecto type. The process function will be nil if no result set is expected from the query.