Monday, 25 April 2016

Top 44 CloverETL Interview Questions Answers


1). Explain what is CloverETL?
Ans: CloverETL is a Java-based data integration ETL platform for rapid development and automation of data transformations, data cleansing, data migration and distribution of data into applications, databases, cloud and data warehouses. The product family starts with an open source runtime engine and limited Community edition of visual data transformation Designer.

2). What is ETL?
Ans: ETL stands for Extract-Transform-Load – a data processing operation that performs data manipulations, usually on-the-fly, while getting (extracting) data from a source or sources, transforming it, and storing into target(s). For more information, see the Wikipedia page for ETL.

3). What is data integration?
Ans: Data integration is a broad term used for any effort of combining data from multiple sources into a more unified and holistic view. It usually involves several operations, such as ETL, orchestration, automation, monitoring and change management.

4). What's the difference between ETL and data integration?
Ans: ETL is a form of data integration where data is transformed during transport between sources and targets. While "pure" ETL is focused on the actual transport, data integration usually refers to a broader task of managing ETL tasks, scheduling, monitoring, etc.

5). Why use an ETL tool and why CloverETL in particular?
Ans: ETL or data integration tools replace ad hoc scripts that you would use to transport data between databases, files, web services etc. Over time, these become very difficult to manage and are prone to errors. ETL tools provide you with visual tools to manage, monitor, and update data transformations with ease. CloverETL in particular is a rapid data integration tool oriented to get your job done quickly.

6). What is CloverETL Designer?
Ans: CloverETL Designer is a visual tool for developing, debugging, and running data transformations.

7). What is CloverETL Server?
Ans: CloverETL Server is an automation, orchestration and monitoring enterprise platform for data integration.

8). What is CloverETL Cluster?
Ans: CloverETL Cluster allows multiple instances of the CloverETL Server to run on different HW nodes and form a computer cluster. It allows for high availability through fail-over capabilities, scaling via load balancing, and processing of Big Data through a massively-parallel approach.

9). Which platforms or operating systems does CloverETL run on?
Ans: CloverETL runs on any platform/operating system where Java 1.6 or later is supported. This includes Windows, OSX, Linux, various UNIX systems and others.

10). Is there a free option for CloverETL?
Ans: Yes. There is a 45-day fully featured trial for CloverETL Designer and a trial CloverETL Server (contact There is also a completely free, but feature-limited CloverETL Community Edition.

11). When and how are new versions released?
Ans: There are two major production releases every year. Before each production release, there are two milestone releases that allow early access to new features from the upcoming production version. Production releases are sometimes replaced with bugfix releases that come as needed.

12). What are milestone (M1, M2) releases?
Ans: Milestone releases provide early public access to features that we're working on for the upcoming production release. You can use milestones and their new features to develop, test, and provide us with feedback. However, milestone releases are not covered by CloverCARE support, so we do not recommend putting them into a mission critical deployment. Major changes that can affect existing transformations are usually published in early milestone versions so that you have plenty of time to adapt to possible incompatibilities.

13). Do I need to renew CloverCARE?
Ans: Your CloverCARE support is covered by an 20% annual maintenance fee that grants you access to product updates and standard CloverCARE support. To continue receiving upgrades and support, you need to renew your maintenance every year.

14). Are there any discounts (academic, non profit, volume) available?
Ans: We can offer discounts for various types of organizations and businesses. We can also offer volume deals. Please contact our Sales at or via this Contact Us form.

15). What makes CloverETL stand out against SSIS/Talend/Pentaho?
Ans: CloverETL is a rapid data integration tool. Our main goal is to provide our users with a tool that helps them achieve results quickly, without having to spend time on training, learning, etc. Starting from our examples, you can begin building data transformations quickly. CloverETL is also sharply focused on data integration – it’s a light-footed, dedicated tool.

16). What is CloverCARE and what does it include?
Ans: CloverCARE is our support package included in every commercial deal. Members of our support team are professional experts who are using CloverETL themselves – no outsourcing, no frustrating phone calls. We also support evaluating users during their trial period. CloverCARE offers email, phone, and WebEx support at various SLAs. Please refer to our CloverCARE Support page for more details.

17). Can I upgrade feature by feature (a la carte)?
Ans: --

18). Can CloverETL be embedded in my product?
Ans: The short answer is yes. CloverETL technology can be embedded in various ways. You can embed CloverETL Designer, CloverETL Server or even just the data processing engine running under the hood. Some of our customers also use white-labeled CloverETL technology in their product offerings. For additional details, please read our OEM section.

19). How scalable is CloverETL?
Ans: CloverETL technology scales really well. You can start with the CloverETL Designer running on your laptop processing thousands of records then move onto the CloverETL Server with its automation capabilities to crunch millions of records. If you happen to hit any Big Data problems, then the CloverETL Cluster is able to cope with any data volume through its massively-parallel data processing capabilities.

20). Does CloverETL support Big Data?
Ans: CloverETL technology naturally fits the processing of Big Data. Its inherent pipeline-parallelism and massively-parallel processing facilitated by CloverETL Cluster allows you to cope with Big Data problems. It’s also able to cooperate with other Big Data related technologies like Hadoop, Hive, and others.

21). What kind of data can I process in CloverETL?
Ans: CloverETL can process any structured or semi-structured data whether stored in a database, file, or other system. Data sources and data targets alike can be a combination of various independent databases and files.

22). How do I get my newly purchased licenses?
Ans: You'll receive an email with your account information (email and password) that you can use to Sign In here. From there, navigate to Licenses & Downloads where you can get both license keys and download all the software.

23). How do I transition from Designer to Server?
Ans: There is a direct upgrade path from the desktop Designer to the Server environment. Your already existing work can be transferred to the Server without any additional effort. Designer manages projects in workspaces on your local drive. You can simply export these to Server sandboxes (via File > Export > CloverETL > Export to CloverETL Server sandbox) and continue working remotely on the Server.

24). How do I transition from Server to Cluster?
Ans: CloverETL Cluster is basically a bunch of Server instances connected together into a single cluster. When you move into Cluster, we recommend reading about various types of sandboxes and how to process data in parallel

25). I purchased CloverETL, but my license is set to expire in two months. Why?
Ans: If you feel there's been an error, please contact our Sales at or via this Contact Us form. Usually we issue temporary licenses immediately once a Purchase Order is received. We then replace the temporary licenses with unlimited ones once the payment is processed.

26). My evaluation license expired. Is it possible to extend the evaluation period?
Ans: Yes, you can ask for trial extension here.

27). Do you have any plans for selling the company or being taken over?
Ans: Our mission is to be a leader in data integration and stay true to providing high quality product and services. You can read more in this CloverETL Manifesto.

28). What files are supported?
Ans: You can process virtually any file containing data, including delimited files, fixed-length record files, binary files or mix of these. Popular file formats are also supported: Excel XLS/XLSX, XML, JSON, dBase DBF, emails, Lotus Notes Domino.

29). What databases are supported?
Ans: CloverETL supports standard relational databases via JDBC. Others include Oracle, Informix, Microsoft SQL Server, Access, MySQL, Postgres, Sybase, etc. Also, some modern NoSQL or columnar databases are supported too, e.g. MongoDB, Exasol, HP Vertica, HDFS or S3.

30). Can I read and write remote files (FTP, SFTP, HTTP/S, etc.)?
Ans: Yes. Please refer to Supported File URL Formats for Readers and Supported File URL Formats for Writers.

31). Can I read and write data using Web Services or REST APIs?
Ans: Yes. There are dedicated components for that: WebServiceClient and HTTPConnector. Also, many components support remote data - please refer to Supported File URL Formats for Readers and Supported File URL Formats for Writers.

32). Do you support Apache Hadoop and/or Hive?
Ans: Yes, Hadoop is supported for both HDFS storage, as well as running MapReduce jobs. Hive is also supported. Please refer to Hadoop connections, Hive connection.

33). Can I use data from cloud providers such as Amazon S3?
Ans: Yes, you can access data on Amazon S3. For more please read Supported File URL Formats for Readers and Supported File URL Formats for Writers.

34). How do I use Designer to develop on the Server? Do I need to deploy?
Ans: The Designer connects directly to Server sandboxes so you're working live on the Server. There is no need to deploy your local edits or anything. Whenever you're connected to a Server sandbox and run a transformation or jobflow, it is executed on the Server, not locally.

35). Can I run a transformation without Designer? How?
Ans: Yes, CloverETL Server provides numerous automation functions, including scheduled execution, web services, event listeners, etc.

36). Can CloverETL Server be deployed to Amazon EC2?
Ans: Yes, there are several projects running CloverETL hosted on Amazon EC2 servers. As data transformations are heavy on I/O, make sure you pick a "high I/O" instances. The installation does not require any additional tricks.

37). Can CloverETL handle secure data transfers (HTTPS, SFTP, FTPS, etc.)?
Ans: Yes, you can access all of these protocols. For more please read Supported File URL Formats for Readers and Supported File URL Formats for Writers.

38). Can sensitive information, such as passwords in connections, be securely hidden?
Ans: Yes, CloverETL Server supports encrypted secure parameters so that sensitive information are not stored in plain-text readable form in graphs, connections etc.

39). Can I use projects developed in Trial (or Community) in commercial an vice versa?
Ans: Yes, everything that you create in Community or Trial can be opened and further developed in any commercial edition of CloverETL. However, CloverETL Community cannot run all transformations created using the Trial or commercial products due to its limitations.

40). Can I create my own custom component or function via a plugin?
Ans: Yes, there are two nice articles you can read on our blog to help you do so: Creating your own component and Custom CTL functions.

41). How do I upgrade CloverETL Designer to the latest version?
Ans: We recommend uninstalling the old version and performing a fresh install of the new one. Don’t worry, all your work is safe – it’s always stored outside the installation files.

42). How do I upgrade CloverETL Server to the latest version?
Ans: -

43). Do I need an application server to run CloverETL Server? If yes, which one?
Ans: We provide a default, easy-to-start bundled package of CloverETL Server with pre-configured Apache Tomcat and Derby database. It's a good, simple start. However, if you wish to use an application container of your own, CloverETL supports a number of industry standard J2EE application servers such as Apache Tomcat, GlassFish, Weblogic, WebSphere, JBoss and Jetty.

44). Which versions of application servers does CloverETL Server support?
Ans: Currently CloverETL supports Apache Tomcat 6.0.x, Glassfish 2.1, JBoss 5.1 or JBoss 6.0, Jetty 6.1.x, WebLogic 11g (10.3.6), WebLogic 12c (12.1.1), Websphere 7.0

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1 comment:

  1. I like your writing style, it was very clear to understanding the concept well; I hope you ll keep your blog as updated.
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