Question

I have a PostgreSQL schema defined using liquibase. I have used ‘SERIAL’ datatype. For these datatypes, the database creates a sequence in it’s pg_catalog table with some specific name. Now I am porting my application to support Oracle. I added a separate change-set for creating a sequence. The sequence name created by PostgreSQL is very large and Oracle does not allow it. I need to modify my schema definition such that both would have same sequence name. This is because I am using hibernate and need to specify the same in the respective hbm files.

The alternative that I can think of is to have a different change set for PostgreSQL and Oracle. For PostgreSQL, it would have create table tag that would generate query something like mentioned here [http://www.postgresql.org/docs/8.1/static/datatype.html#DATATYPE-SERIAL]. And then another change-set for Oracle to just create the table and associated sequence.

I am interested in knowing if this is the right and only approach to achieve this.

Answer 1

In PostgreSQL you can create the sequence with any name. The data type serial is just shorthand for – I quote the manual here:

CREATE SEQUENCE tablename_colname_seq;
CREATE TABLE tablename (
    colname integer NOT NULL DEFAULT nextval('tablename_colname_seq')
);
ALTER SEQUENCE tablename_colname_seq OWNED BY tablename.colname;

So use shorter names for your sequences. Or use shorter table names and save yourself the hassle.