Uniques With Multiple Fields

Motivation

It is needed for Air (663686) to have an unique on a fields combination From and Till varchar fields of wdoc.air.UPPayout Problems:

• old uniques engine is not suitable because From and Till are both varchar fields. Only one varchar field in one unique is allowed

Functional design

TABLE TablePlan INHERITS CDoc (
    TableState int,
    Name varchar NOT NULL,
    ...

    UNIQUE (TableState, Name), -- unnamed UNIQUE table constraint, parser generates unique QName `main.TablePlan$uniques$01` automatically
    CONSTRAINT UniqueTable UNIQUE (TableNumber), -- named UNIQUE table constraint. Parser generates unique QName `main.TablePlan$uniques$UniqueTable` automatically
    UNIQUEFIELD Name, -- deprecated. For Air backward compatibility only. No according `IUnique` is generated
)

Technical design

We can use existing Uniques view

Context

• #151

Issues

• https://github.com/voedger/voedger/issues/867