PostgreSQL does not support identity columns; however, the database provides auto-incrementing of column values using pseudo datatypes SERIAL and BIGSERIAL. These types actually create columns of type INTEGER and BIGINT respectively, and auto increment by internally creating a sequence and then setting a DEFAULT clause on the column that takes the next value from the sequence.

To use this functionality with the DB Access Module for PostgreSQL, associate an RWDBIdentityConstraint object with a column and set the column’s datatype to either RWDBValue::Long or RWDBValue::LongLong. For a valid RWDBIdentityConstraint object attached to a column of type RWDBValue::Long, the module creates a column of type SERIAL. Similarly, a column with a valid constraint object and a type of RWDBValue::LongLong results in a column of type BIGSERIAL.

All other RWDBValue type columns, when associated with a valid RWDBIdentityConstraint object, produce a not supported error, aborting SQL generation.

The DB Access Module for PostgreSQL ignores all identity constraint attributes since they are not supported by the SERIAL and BIGSERIAL datatypes. Consequently, while fetching a table schema, the columns created as the types SERIAL and BIGSERIAL are not fetched with a valid RWDBIdentityConstraint object; rather, they will have a DEFAULT clause containing a reference to the internal sequence.