What is a Data Staging Area? | Staging Data Simplified 101

The Data Staging Area is a temporary storage area for data copied from Source Systems. In a Data Warehousing Architecture, a Data Staging Area is mostly necessary for time considerations. In other words, before data can be incorporated into the Data Warehouse, all essential data must be readily available.

It is not possible to retrieve all data from all Operational databases at the same time because of varying Business Cycles, Data Processing Cycles, Hardware, and Network Resource Restrictions, and Geographical Variables.

Here’s all you need to know about Data Staging Area, as well as some key pointers to keep in mind before you start the process.

What is Data Staging?

During the Extract, Transform, and Load (ETL) process, a Staging Area, also known as a landing zone, is an interim storage region used for Data Processing. The Data Staging Area is located in between the Data Source(s) and the Data Target(s), which are typically Data Warehouses, Data Marts, or other Data Repositories. 

Data Staging spaces are frequently ephemeral in nature, with their contents being wiped before performing an ETL process or shortly after it has been completed successfully. However, there are architectures for staging areas that are designed to hold data for long periods of time for preservation or debugging purposes.

You can learn more about data ingestion architecture here.

Why do you need to Stage Data?

There is no designated space available for testing data transformations in a direct data integration strategy, where the data is extracted, transformed, and then loaded to the new storage. Before being loaded to the target system, data from the source can be replicated, reformatted, and tested in a staging area in data warehouse.

Most firms today have several Data Sources to derive information. Before being loaded into the new system, the extracted data must be polished and cleansed, as well as have the right format and structure. A Staging space is useful in this situation. Data is altered, replicated as needed, linked and aggregated if necessary, and then cleansed in this intermediate layer.

What is a Data Staging Area?

The Data Staging Area is made up of the Data Staging Server software and the data store archive (repository) of the outcomes of the extraction, transformation, and loading activities in the data warehousing process.

The archival repository stores cleansed, converted data and attributes for loading into Data Marts and Data Warehouses, while the Data Staging software server saves and alters data taken from OLTP data sources.

A Data Staging Area is a design concept for a Data Pipeline. It is a location where raw/unprocessed data is stored before being modified for downstream usage. Database tables, files in a Cloud Storage System, and other staging regions are examples.

Example:

It’s reasonable to extract sales data on a daily basis, but daily extracts aren’t appropriate for financial data that needs to be reconciled at the end of the month. Similarly, extracting “customer” data from a database in Singapore at noon eastern standard time may be appropriate, but it is not appropriate for “customer” data in a Chicago database.

Data in the Data Warehouse can be permanent (i.e., it lasts for a long time) or transitory (i.e., it only lasts for a short time) (i.e. only remains around temporarily). A data warehouse staging space is not required for all enterprises. For many firms, using ETL to replicate data straight from operational databases into the Data Warehouse is a viable option.

External Staging

The area where data staging takes place outside a data warehouse is commonly referred to as External Staging. This area is often hosted by cloud storage providers such as Google Cloud Storage (GCS) or Amazon Web Simple Storage Solution (AWS S3).

Internal Staging

Unified cloud data warehouses in modern approaches often use an internal staging process that involves creating raw tables separate from the rest of the warehouse. These raw tables then undergo a transformation, cleaning, and normalization process in an ‘ELT staging area’. A final layer is then used to present only the cleaned and prepared data to BI tooling and business users, allowing data teams to curate a single source of truth, reduce complexity, and mitigate data sprawl.

What is the Role of a Data Staging Area in Warehouse ETL?

• A Data Staging Area has a single purpose: to hold raw data from Source Systems and to provide a space for transitory tables created during the transformation process. 
• The function of the Data Staging Area varies depending on the design methodology and ETL toolset, but the Target Audience is always the ETL process and the Data Engineers who are responsible for designing and maintaining the ETL. 
• This does not diminish the need for data governance in a Data Lake, but it does make it much easier to manage when contrasted to a large number of individuals and processes that may access it.

To learn more about ETL, check out our in-depth guide.

What are the Advantages of a Staging Area?

The efficiency of employing the Data Staging Area is heavily dependent on the business requirements and the ETL system’s operating environment. Here are a few reasons why you should choose Data Integration products such as Hevo Data that have a Staging Area.

• Recoverability: In the event that operations are corrupted, data should be retrieved. As a result, stage data after it has been collected from the source and after any substantial transformations have been made to it. In the event that Data Corruption occurs during the latter phases, the staging steps will function as recovery points.
• Backup: Backups let you store, compress, and archive data all the way down to the database level. When large amounts of data are sent, one issue that usually arises is Data Backup on such a large scale. Data can be sent in pieces that can be readily preserved and archived using staging areas.
• Auditing: By comparing the original input files (with transformation rules) and the output data files, staged data can make the auditing process easier. The data connectivity between the source and the goal is lost as the ETL process becomes more complicated, which can lengthen and complicate the auditing process. Staging methods enable a smooth auditing procedure while keeping the data lineage intact.

What are the Disadvantages of a Data Staging Area?

• If the transformation process slows down, the staging procedure will come to a halt as well.
• There might be some variation in the use of disc space because the data must be dumped into a local area.

Staging & Data Warehouse Architecture

A Data Warehouse’s Architecture is seen in the image below. Through the data warehouse, end users have immediate access to data collected from a variety of Source Systems.

The image above shows metadata and raw data from a standard OLTP system, as well as a new type of data, called Summary Data. Summaries are a way to pre-compute frequent, time-consuming processes so that data can be retrieved in a fraction of a second. A common data warehouse query, for example, might be to get August Sales. A materialized view is a summary in an Oracle database.

An Enterprise Data Warehouse is a centralized repository of raw data that serves as the hub of your data warehousing system (EDW). By storing all essential business information in the most complete format, an EDW delivers a 360-degree insight into an organization’s business.

Data Warehouse with a Staging Area

As demonstrated in the image below, you must clean and prepare your operational data before putting it into the warehouse. Although most data warehouses employ a staging area instead, this can be done programmatically. A Staging Area makes data cleansing and consolidation for operational data from numerous Source Systems easier, especially for corporate data warehouses that consolidate all of an organization’s important data. This typical architecture is depicted in the image below.

Data Warehouse with Data Marts & Staging Areas

Although the architecture shown in the image above is quite standard, you may want to alter the architecture of your warehouse for different groups within your company. You can do this by incorporating Data Marts, which are systems tailored to a specific industry. The image below depicts a scenario in which purchasing, sales, and inventory are all separated. In this case, a financial analyst would wish to mine past data to develop forecasts about client behavior or examine historical data for purchases and sales.

Essential Steps in Data Staging Areas

The data staging area serves as the gateway to successful data integration and analytics, preparing data for subsequent stages by ensuring it’s cleansed, transformed, and ready for analysis.

Let’s delve into the sequential steps undertaken within the data staging area:

1. Data Extraction

This initial step involves extracting data from various source systems, including databases, CRM systems, and ERP solutions. The staging area serves as the primary landing zone for this extracted data, allowing it to be collated in one centralized location for further processing.

2. Data Profiling

Before proceeding, it’s crucial to understand the nature and quality of incoming data by assessing completeness, consistency, and anomalies. Data profiling provides insights into potential issues that need addressing in subsequent steps.

3. Data Cleansing

Raw data often contains errors, duplicates, or inconsistencies that need to be identified and rectified. Cleansing operations in the staging area ensure that data is of high quality before it proceeds further.

4. Data Transformation

Since data sources can have varying structures, formats, and standards, transformation becomes vital to align data with the target system’s schema. Transformation processes ensure data compatibility with the target system.

5. Data Validation

Once data is cleansed and transformed, it’s imperative to validate it against specific business rules or criteria to ensure accuracy and relevancy. The staging area enforces validation checks to further ensure data quality before proceeding.

6. Data Integration

The staging area acts as the ground for data integration, ensuring cohesiveness in the resultant dataset.

7. Temporal Storage

Sometimes, there’s a need to hold processed data temporarily before loading it into the target system. The staging area provides buffering capacity, ensuring data readiness for subsequent stages.

8. Data Loading

In this final step, the prepared data is loaded into the target system, such as a data warehouse or data mart. The staging area ensures a smooth process, as data is already in a compatible format, cleaned, and validated.

In summary, the data staging area serves as a meticulously organized processing hub, guiding data through essential steps to ensure its accuracy, reliability, and readiness for insightful analysis.

Popular Tools for Data Staging Areas: Streamlining Data Processes

In the complex landscape of data management, data staging areas play an indispensable role in processing, cleaning, and preparing data for further analysis. Various tools have been developed to facilitate and optimize these processes within the data staging area. Let’s explore some notable examples:

1. Apache NiFi
2. Microsoft SQL Server Integration Services (SSIS)
3. Apache Kafka
4. AWS Glue
5. Google Cloud Dataflow
6. Pentaho Data Integration

In conclusion, the choice of tool for the data staging area depends on specific organizational requirements, data sources, infrastructure, and desired outcomes. Nevertheless, these tools are instrumental in ensuring optimal functioning of the data staging area, laying the groundwork for accurate, reliable, and timely data analytics.

Data Staging Layers vs Data Lake: What is the Difference?

Security

To get the most out of the large range of data accessible in the lake, Data Scientists and Analysts frequently have zero or minimum protection applied to the data they may access, which can lead to poor accuracy and duplication of effort.

A Staging Layer is often only accessed by warehouse developers for the sole purpose of filling and providing “single source of truth” in the data warehouse. After that, the populated data warehouse is made broadly available throughout the company. The developers should have full Security Access to the Staging Layer, but the data that emerges from it may be restricted to certain business sectors or security roles.

Development Effort

Due to the Ad-hoc nature of Data Access, the schema on the reading approach lends itself to quicker development timescales, but the schema on the write approach has a slower time to delivery in comparison because it takes longer to design and test the appropriate load logic and data objects.

When numerous users independently create comparable or overlapping datasets, Ad-hoc access to a data lake might raise the odds of logic repetition. Due to the lack of conforming dimensions, this repetition can result in decreased accuracy and duplication of work, as well as the establishment of data silos.

A Staging Layer, on the other hand, will normally have a greater level of accuracy and less duplication of effort because a dataset is typically only developed once, following an agreed-upon set of business rules, and the ensuing computations and transformations are generally considered as correct.

Users

There are significant variances in the types of users that each system can accommodate. Data Scientists and advanced Data Analysts from a number of business disciplines generally use a Data Lake to develop standalone solutions for Advanced Analytics, Data Mining, and Machine Learning, as well as other downstream business processes.

How does a Data Staging Area Simplify Quality Challenges?

• You can execute more complex operations on the data in a Staging Area. It enables comprehensive semantic and content modification. Since the data does not reside in either the Source or the Destination, you have complete control over it. Any operations you do will have no effect on the data set’s other tuples.
• It enables you to do fine-grained and coarse-grained operations on full datasets at the same time.
• Certain Datasets can be separated and aligned on a completely different trajectory, which can then be used to extract business insights in the future.
• When the Source or Destination systems have hardware or network limitations, a Staging Area provides flexibility. It can also be tailored to fit around business and data processing cycles.
• Most Staging-area-equipped solutions provide advanced database capabilities such as Replication, Aggregation, and Cleansing.

Best Practices/Rules to build your Data Staging Layer

• The Data Staging space must be owned by the ETL team in charge of the entire process, and no one else should have access to it. Since the Staging files aren’t intended for display, they don’t have any Indexes or Aggregations to aid queries. In brief, there are no Service-Level Agreements for Staging Area files.
• Design your data staging area to handle future data volumes.
• Validate and cleanse data as it enters the data staging area to ensure consistency and freedom from corruption.
• Maintain a version control system for data staging area processes to track changes and understand the history of data handling.
• Implement robust security measures, including encryption, access controls, and audit trails, to protect sensitive data.
• Set up monitoring tools to detect bottlenecks, failures, or anomalies in real-time for swift troubleshooting.
• Define and enforce data retention policies to move or archive data after its purpose in the staging area is fulfilled.
• Regularly back up configurations, scripts, and crucial data to safeguard against data loss and facilitate quicker recovery in case of failures.
• The Staging Area should not be accessible to users.
• Data maintained in the Staging Area should not be used to generate reports.
• Only ETL operations should be able to read and write to the Staging Area’s data files.

Conclusion

As organizations expand their businesses, managing large volumes of data becomes crucial for achieving the desired efficiency. Data Staging Area powers stakeholders and management to handle their data in the best possible way. In case you want to export data from a source of your choice into your desired Database/destination then Hevo Data is the right choice for you! 

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