Myujth

I have a table

class MyTable 
 Long revisionGroup
 Integer revisionNum = 1

 ...

 static constraints = 
 revisionGroup unique: 'revisionNum'
 
 static mapping = 
 revisionGroup generator: 'auto'
 

I want to be able to do the following:

//Save new data.
MyTable myTable1 = new MyTable().save()
//Do "soft update" of data by saving new revision.
MyTable myTable2 = new MyTable(revisionGroup: myTable1.revisionGroup, revisionNum: myTable1.revisionNum + 1).save()
//Save new data.
MyTable myTable3 = new MyTable().save()

Expected data:

myTable1: id = 1, revisionGroup = 1, revisionNum = 1
myTable2: id = 2, revisionGroup = 1, revisionNum = 2
myTable3: id = 3, revisionGroup = 2, revisionNum = 1

Unfortunately, a validation error is thrown when running new MyTable().save() that revisionGroup is null.

I know this can be done by making revisionGroup a String and using a GUID, but I need to use a Long that auto increments.

After some digging, it looks like this isn't possible conventionally: Hibernate JPA Sequence (non-Id).

In the comments of the accepted answer, a better solution for PostgreSQL is @Column(columnDefinition="serial"), which translates here to a mapping of revisionGroup sqlType: 'serial'. I'm using SQL Server, though, and using the mapping revisionGroup sqlType: 'BIGINT IDENTITY(1,1)' causes Grails to skip the creation of the entire MyTable table.

What is the correct mapping to use?