[session] drop useless getter and setter for security Those function have very few user and does not anything fancy. Internal user now access tx.read/write_security directly. External user have been blessed with a writable property. They are only interested in the write part of they did not used the return of the removed function. They access it through the session since I prefer the external world to not be aware of Transaction yet.

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if repo.system_source.dbdriver == 'postgres':

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    sql('ALTER TABLE appears ADD COLUMN weight float')

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    sql('UPDATE appears SET weight=1.0 ')