Thanks this is helpful, but I was curious. If there are versions of postgres installed on the system, how does ambari-server choose which one to run with? I actually have another system where I'm seeing the opposite. In this case postgresql-10 is running and postgresql (9.2) is not active after a restart. I'm just trying better understand how it choose which postgres service to start? ... View more

@Henry2410  MySQL Server is intended for mission-critical, heavy-load production systems as well as for embedding into mass-deployed software. On the other hand, Snowflake is detailed as "The data warehouse built for the cloud".   There's not really an equivalence between MySQL and Snowflake use cases. What you are asking really is whether Snowflake can play the role of an OLTP database. Snowflake is not an OLTP database. It is an OLAP database. So generally speaking I would say no.   Snowflake is a cloud-based warehouse and it would be used most of the times for OLAP purpose back to your questions, Snowflake can be used under the following conditions: If you have only inserts into target table and not much updates to the table we can achieve good performance by using cluster by and other inline views Having said that, to explore your use case a little bit more I would ask yourself or your stakeholders the following questions: Do you need millisecond response times for INSERTs, UPDATEs, and SELECTs? Does your application tool require indexes? Does your application need referential integrity and uniqueness constraints enforced? If you said yes to ANY of 1, 2, 3 then go MySQL. If you said NO to ALL 1, 2, and 3, then Snowflake might be viable. But even then I would not recommend it, as that is not what Snowflake was built for. ... View more

@LeticiaAraujo  Log4j properties set the properties that control logging activities for each service running in your Hadoop cluster. This is something that every site can customize according to its needs like enabling DEBUG will generate detailed by huge logs is you want to analyze the issue with your service. Rotation of the logs, compression format or logfile size etc Logging services is a topic on its own, and here is a good source for reading log4j  the most common task is enabling DEBUG and Log rotation and it's date format. ... View more

Thanks for your efforts Shelton. ... View more

@Shelton Yes, i understand and know how to change this through CM, my question is that i changed it manually in one of the nodes this setting, will the node that this config locally where i changed it or will take what is the value in CM? what i need to do if i want to revert the manual change through CM and not reverting the change manually from the node.   I want to proof that manual changes has no impact and it can be overriden through CM. i provided ACL only as an example but it can be any other config ... View more

@florianc  Ambari uses a backend database to store all the configuration and changes after the initial install. It can be a derby, Mysql, Oracle, or MariaDB like it is in my case. Ambari 3.1.0 has around 111 tables that reference each other through primary and foreign keys so it's very easy to write an efficient SQL to output the desired information once you target the right tables. In a nutshell, the tables are intuitively named like alert_*, blueprint_* Cluster_* host_* _repo_* topology_* etc      Logically the  Cluster family should be our focus. I spun a single node cluster to demo this  I have changed the knox.token.ttl because if you have ever worked with Knox Admin the UI is timesout so fast quite annoying.   Below is an Ambari Ui and Database proof to confirm that all changes are persisted in the Ambari back end database. Note It has happened to me in cases of upgrade where the upgrade is stuck in incomplete status I have ad to go and physically change the status in the database to bring my cluster to life 🙂 MariaDB [(none)]> use ambari; MariaDB [ambari]> show tables; I zeroed on the serviceconfig table  MariaDB [ambari]> describe serviceconfig; From the output, I easily chose my rows  MariaDB [ambari]> select service_name ,user_name,note from serviceconfig; I then added a filter to grab the version and note to validate it against my Ambari UI  MariaDB [ambari]> select service_name,version ,user_name,note from serviceconfig;   So here is the Ambari UI screenshot Voila the confirmation that changes doe in Ambari UI is persisted to whatever backend database is plugged Ambari. I have used the same technic to get blueprints : Happy hadooping ... View more

@ARVINDR : Thanks for the info on that cluster creation part. Did you try to check the ACL. ... View more

@Shelton    I can see Ambari created Headless Keytab but didn't see how this is being used or configured. Any insight on how Headless Keytab configured? Thanks! ... View more

@Sagar1244    Have you copied the Oracle jdbc jar file to /usr/hdp/current/zeppelin-server/interpreter/jdbc/ then configure the zeppelin jdbc interpreter as shown. Restart the interpreter and retest ... View more