ETL (extract, transform, and load) process is not a rule or a compulsory model for data integration and governance. Instead, it is considered one of the most effective approaches to extracting data from various resources, transforming this data into a compatible form, and finally loading it into the data warehouse schema. Currently, a wide range of ETL tools have been developed due to the advancement of the big data world and the high demand for business intelligence. In this blog, we will compare several prevalent ETL tools (AWS Glue, Pentaho, Talend, etc.) and investigate their pros and cons. Additionally, some practical cases corresponding to each tool will be displayed.

What are ETL tools?

Extract-Transform-Load (ETL) tools are specialized tools that are responsible for extracting data from multiple sources, cleansing, transforming, customizing, and importing it to a data warehouse.

Since 1970, organizations have started to exploit diverse data repositories to archive multiple business information. From 2018 to 2026, it is estimated that ETL tools and solutions will expand significantly due to the enlargement of the ETL market. In addition, an increase in Big Data, the Internet of Things (IoT), demand for Cloud Computing, and business data volume accelerates the power of ETL tools.

Recently, many organizations have taken advantage of ETL tools to manage big data sources’ volume, variety, and velocity.

According to Talend, more than 50% of enterprise data is allocated to the cloud system, emphasizing the influence of external data sources in every company. Hence, it is urgent to implement modern tools to efficiently process and integrate data by entering data warehouse space and accommodating workloads.

How to evaluate ETL tools?

Currently, there are various technology providers, such as AWS, IBM, Oracle, Talend, etc., offering ETL solutions. However, each enterprise has to decide which ETL tools are most efficient and match their operations. A standard framework was conducted based on academic research to compare ETL tools against each other after referencing different articles, journals, and books.There are four categories in the finalized framework as below:

• Price
• Functionality
• Ease of use
• Architecture

Price

The first category is “Price”. The Oracle expert – Abramson rated costs as one of the most important criteria to assess an ETL tool. This criterion involves several fundamental “costs” that the organizations have to take into account:

License Cost: it emerges when buying one license.
OS Costs: it is operating system costs.
Support Costs: it occurs when raising additional service support.
Hardware cost: it is an amount of money used to buy the hardware that is needed to run the program.

Functionality

According to the author of Information Management Direct – Mark Madsen, the “Functionality” category was conducted to check if they could process their data.
It relates to a dozen of functionalities, namely:

• Basic processing support
• Performance
• Transformations
• Cleansing
• On-demand support
• Secure Packages
• ETL reporting
• Scheduling
• Metadata
• Rollback
• Connectivity
• Calculation
• Data Warehouse support
• Aggregation
• Reorganization.

Ease of use
The category “Ease of Use” is created to determine the usability of the ETL tools. According to Mark Madsen, it is difficult to establish criteria here because every user has different preferences on how a program should work (Madsen, 2008). After research, they established the following criteria for comparison in this category:

• Completeness of the GUI (Graphical user interface): a good visual interface is given.
• Custom Code: it allows the user to enter source code or to customize the process highly.
• Integrated Toolset: if the ETL tools are not integrated into one program, it is possible to purchase backup tools or add-ons for the product.
• Debugging support: it allows users to set breakpoints to analyze errors (Madsen, 2008) easily.
• Source Control: it is easy for the user to select and integrate different sources.

Architecture
According to the Clickstream Data Warehouse book, the “Architecture” indicates information about the hardware and operating system (OS) supported by the software in terms of platform, backup, and performance. Although each ETL tool advances different architectures, the authors of the research concluded several integral criteria:

4 types of ETL tools

Recently, many ETL tools have been transformed and developed to satisfy various needs and requirements of users. These appliances fall into different categories based on several criteria such as functionality, structure, volume performance, etc. According to Hubspot, there are four basic types of ETL tools, including Open-source, Enterprise, Cloud-based, and Custom ETL tools.

Open-source ETL tool
Open-source tools are freely available and created by software developers. Each tool has distinct characteristics in terms of quality, integration, ease of use, adoption, and availability of support. Recently, there have been many open-source options for organizations to take into account, namely Pentaho, Hadoop, Hevo Data, Airbyte, etc. This blog will take Pentaho and Talend Open Studio as examples of open-source ETL tools.

• Pentaho

Pentaho Kettle Enterprise, also known as Pentaho Data Integration, is a platform’s ETL model. Accordingly, it allows extracting data from numerous sources, transforming, and loading it into the Enterprise Data Warehouse (EDW), either a Relational Database or NoSQL Database. The organization could utilize the Pentaho tool for further transformation from EDW to Data Marts or Analytic Databases.

The table below indicates a comparison between Pentaho and other ETL tools:

Cloud-based ETL tool
Many cloud service providers (CSPs), such as Amazon AWS, Google Cloud Platform, and Microsoft Azure, have developed ETL tools on their own infrastructure. It has resulted from the proliferation of cloud computing and integration-platform-as-a-service. Currently, AWS has taken the largest market share among various cloud-based ETL tools.

• AWS Glue

AWS is a prevalent cloud-based ETL tool that assists visual and code-based clients, which would deliver sound business intelligence. The serverless platform provides multiple features, such as the AWS Glue Data Catalog for detecting data from various organizations and the AWS Glue Studio for visually arranging, performing, and managing ETL pipelines.

The map below is an illustration of how to create, run, and assess the ETL process without writing code, thanks to AWS Glue Studio. Initially, you just compose ETL tasks to move and transform data with the drag-and-drop editing tool. Then AWS Glue will automatically develop code for your tasks. Additionally, the task runtime console of AWS Glue Studio allows you to manage ETL execution and track the progress.

Commercial ETL tool (Enterprise)
Commercial tool distinguishes itself from the other two by 2 notable features: Modification and Data inputs. In terms of modification, while open-source software allows basic rights to the general public, commercial tools are modified by only the organization that created them. Additionally, unlike cloud-based tools that only process online data sources, commercial ones accept sources from online and offline databases.

Commercial tools offer graphical user interfaces (GUIs) for designing and executing ETL pipelines. It also facilitates relational and non-relational databases such as JSON and XML, event streaming sources, etc.

The next section will investigate Informatica PowerCenter as an example for a better understanding of enterprise ETL tools.

- Informatica PowerCenter

Currently, Informatica is an industry leader in ETL. It has the best-in-class data integration products for quickly integrating data and applications.

Informatica PowerCenter is an on-premise ETL tool that can link to a number of different legacy database systems. The tool also allows for data governance, monitoring, master data management, and masking. Users can view servers on the company’s premises using ETL, a batch-based ETL application with a cloud counterpart. It also provides a number of data management and software-as-a-service options.

Informatica is an ETL tool that can be used to build corporate data warehouses. It also provides a range of data masking, duplicate data, merger, consistency, and ETL products. The ETL tool allows users to connect to and view data from a variety of sources, as well as perform data processing.

Pros
– Easier for server manager to schedule
– Informatica’s archive manager can help with data preservation and recovery
– Informatica is a mature, eminent business data integration framework

Cons
– Informatica is a bit expensive. It is costlier than Datastage but cheaper than Ab Initio.
– To use Informatica’s services, one must pay the single and multi-user licensing costs
– Only available on a commercial basis.
– Informatica’s custom code incorporation through Java conversion is relatively complicated

Custom ETL tool
Despite the widespread use of graphical user interface (GUI) – based solutions, some organizations choose hand-coded ETL tools for their ETL processes. In some contexts, the custom approach could be cheaper, faster, and more attainable than GUI-based tools.

Enterprises would build their custom ETL tools based on programming languages such as Python, R, Java, etc. In academic research, the authors introduced several custom tools, namely Pygrametl and Petl (Python-based), Scriptella (Java-based), etl (R-based).

- Petl

The most notable example is Petl, a general-purpose Python library that can carry out typical ETL processes, supported by the MIT License. PETL which is used for extracting, transforming, and loading tables of data.

The design of Python ETL (petl) is easy and convenient for users. Hence, the tool is preferable for working with mixed, unfamiliar, or heterogeneous data. In addition, you can build tables in Python from various data sources such as CSV, XLS, HTML, TXT, JSON, etc, and drive them to the prescribed data storage. Another benefit of using Petl is that it can be used for migrating between SQL databases efficiently and smoothly.

ETL tools are of immense importance in the field of business intelligence. Using a proper ETL tool might drastically affect the business outcome. Hence, it is important to choose the right ETL tool according to business requirements and investments. This blog presented a review of distinct features of some mainline ETL Tool suites and how these tools are applied in reality. In the future, the market of ETL tools will expand significantly due to the demand for data integration and governance. More importantly, these tools have always been transformed and upgraded, which requires humans to learn and adapt to changed things.

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