Sequences migration

Sequences migration #

There is little work on sequences. Sequences are very similar in PostgreSQL and Oracle. A few points need attention, though.

On a general basis, clauses preceded by NO to use default values need a space between NO and the rest of the clause to be ported to PostgreSQL. For example, the NOMAXVALUE clause from Oracle has to be translated to NO MAXVALUE for PostgreSQL. However, Oracle’s NOCACHE clause has no equivalent in PostgreSQL, but it can be converted to CACHE 1, or simply removed. Only the ORDER and NOORDER have no equivalent in PostgreSQL, as they are a specificity of Oracle¬†RAC.

References:

Sequence usage #

Sequences aren’t use the same way in PostgreSQL and Oracle. Oracle’s syntax is sequence_name.operation, while PostgreSQL’s syntax is operation('sequence_name').

For instance, the following call, from Oracle:

sequence_name.nextval

has to be rewritten to this for PostgreSQL:

nextval('sequence_name')

References:


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