La actualización de Ambari 2.2.1 a 2.4.1 falla con la siguiente excepción:
Exception in thread "main" org.apache.ambari.server.AmbariException: ERROR: relation "unq_users_0" already exists
at org.apache.ambari.server.upgrade.SchemaUpgradeHelper.executeUpgrade(SchemaUpgradeHelper.java:207)
at org.apache.ambari.server.upgrade.SchemaUpgradeHelper.main(SchemaUpgradeHelper.java:347)
Caused by: org.postgresql.util.PSQLException: ERROR: relation "unq_users_0" already exists
at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2161)
at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1890)
at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:255)
at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:559)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:403)
at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:395)
at org.apache.ambari.server.orm.DBAccessorImpl.executeQuery(DBAccessorImpl.java:827)
at org.apache.ambari.server.orm.DBAccessorImpl.executeQuery(DBAccessorImpl.java:819)
at org.apache.ambari.server.orm.DBAccessorImpl.addUniqueConstraint(DBAccessorImpl.java:518)
at org.apache.ambari.server.upgrade.UpgradeCatalog230.executeDDLUpdates(UpgradeCatalog230.java:110)
at org.apache.ambari.server.upgrade.AbstractUpgradeCatalog.upgradeSchema(AbstractUpgradeCatalog.java:889)
at org.apache.ambari.server.upgrade.SchemaUpgradeHelper.executeUpgrade(SchemaUpgradeHelper.java:204)
... 1 more
En ambari-server.log vemos el origen del problema:
Error executing query : ALTER TABLE users ADD CONSTRAINT UNQ_users_0 UNIQUE (user_name, user_type)
Solución:
Eliminar esa "constraint":
su - postgres psql alter table ambari.users drop constraint unq_users_0; \q
Y volver a intentar la actualización.