At the moment the hibernate SchemaUpdate tool will export changes like this:

• create a new table
• add a new column
  The hibernate schema update will not:
• drop a table
• drop a column
• change a constraint on a column
• add a column with a not-null constraint to an existing table

For example if I change my column definition from this:

@JoinColumn(name = "unit", nullable = false, referencedColumnName = "pk")

to this:

@JoinColumn(name = "unit", nullable = true, referencedColumnName = "pk")

and then I run schemaupdate there will be no changes detected. This proposal wants to improve the schemaupdate tool to also track changes like change constraints, drop a column or drop a table.