Fail to restart oozie server due to DB schema already exists

When restarting oozie server, error occur when executing :
cd /var/tmp/oozie && /usr/lib/oozie/bin/ooziedb.sh create -sqlfile oozie.sql -run
Error message:
Validate DB Connection
DONE
Check DB schema does not exist

Error: DB schema exists

Stack trace for the error was (for debug purposes):
--------------------------------------
java.lang.Exception: DB schema exists
at org.apache.oozie.tools.OozieDBCLI.validateDBSchema(OozieDBCLI.java:708)
at org.apache.oozie.tools.OozieDBCLI.createDB(OozieDBCLI.java:173)
at org.apache.oozie.tools.OozieDBCLI.run(OozieDBCLI.java:116)
at org.apache.oozie.tools.OozieDBCLI.main(OozieDBCLI.java:67)

Fix: delete the previous oozie-db
Con: will lose your previous data, and might create memory leak.

$ rm -rf /grid/0/hadoop/oozie/data/oozie-db/
$ rm /var/lib/oozie/oozie-server/webapps/oozie.war