this question is based on two threads that have been posted before.
Hibernate using JPA (annotated Entities) and liquibase
Liquibase diffChangeLog against a Hibernate mapping definition
my confusion is if i am using hibernate annotations, do i still need to write changesets in changelog.
also, so many people are using hibernate annotations now, i hope someone could give me an example of the needed things to really get it working. no good example on the internet.
The JPA/Annotation support of the liquibase hibernate diff has not been overly tested and does not cover all cases and annotations, so given the current state it is probably not ready to be relied on as part of a normal workflow.
That being said, even if/when it is fully tested it may make sense to write changesets manually. The hibernate support does a diff between your current database and the database hibernate expects and outputs changesets to move from the current database to the hibernate database. While this often works, there are inherent problems with any database-diff-based process (see http://blog.liquibase.org/2007/06/the-problem-with-database-diffs.html). Personally, since it is best to inspect and possibly modify the changesets that are added by the hibernate diff before executing them I feel it is just as easy to add them myself. That way I can take advantage of higher-level changes (such as introduceLookupTable) which make the changeLog more readable.
There are definitely environments and workflows where the changeset generation is nice, which is why it will be supported, but it is not there yet and you certainly can use liquibase with hibernate without it.