Hi,
I like to propose a more consistent syntax for computed columns and identity
columns:
Computed columns are now defined in DDL as
<ColumnName> [<DataType>] GENERATED ALWAYS AS (<Expression>)
while identity columns (as of FB 3.0 CORE-1385) are defined as:
<ColumnName> {<DataType>|<DomainName>} GENERATED {ALWAYS|BY DEFAULT} AS
IDENITITY
Note the differences:
- for computed columns the datatype is optional (if ommitted the system will
find an appropriate datatype)
- identity columns can be defined as both datatype and domain, where computed
columns can only be defined as datatype
- identity columns can be defined as both ALWAYS (although not yet implemented)
and BY DEFAULT, while computed columns can only be defined as ALWAYS
To make this more consistent, I like to propose to:
- also support domains for computed columns;
- also make the specification of datatype/domain for identity columns optional
(if it is ommitted the system should assume INTEGER);
- also support GENERATED BY DEFAULT for computed columns.
The syntax will then also be more generic (covering both computed and identity
columns):
generated column specification ::= <ColumnName> [{<DataType>|<DomainName>}]
GENERATED {ALWAYS|BY DEFAULT} AS {(<Expression>)|IDENTITY}
What do you think?
Kind regard,
Robert NL
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