Como identificar e eliminar dados duplicados?

Duplicate data refers to multiple occurrences of same data. It typically happens through data entry points, where there is no validation checkpoints. It can occur from bulk data load, which bypasses the main entry that may or may not have validation. Data Integration and updates can also add the possibility of duplicate records.

Duplicates in databases refer to multiple records or entries that contain the same or highly similar data, often unintentionally. These duplicates can exist within a single database table or across multiple tables. Duplicates can arise for various reasons, including data entry errors, system glitches, inconsistent data formats, or merging of data from different sources.

Data duplication can happen to various entities in different forms. However, customer duplication is the most common and challenging problem in almost all data systems. In an operational (OLTP) system, the same customer details can be entered into the database more than once due to lack of uniqueness enforcement. In an integration or data warehouse environment, customer information comes from different source systems with different customer IDs even for the same customer with activities in more than one source system. The other type of data duplication could happen in transactions where the same order or item has been placed multiple times.

Duplicate data is indeed a common yet critical challenge in data management. It's like having unnecessary clutter that can skew analysis and lead to misguided decisions. To add, it's crucial to understand that the impact of duplicate data goes beyond just storage issues. It can affect customer relationships, financial reporting, and even compliance with regulations. Addressing duplicates requires a robust data governance framework and a keen eye for data quality. Tools and techniques like data deduplication, regular audits, and implementing strong data entry standards are key in mitigating this issue. Remember, in the world of data, quality often trumps quantity!

Duplicate records cause additional maintenance and performance issues, which is unnecessary. It causes flaw in the information and leads to incorrect decisions by executives. Some duplicates might damage organization's reputation and might lead to hefty fines on regulatory compliance point.

Duplicate data can lead to inconsistent analysis results due to double counting on the relevant measures, posing a great challenge to data quality. In a data warehouse system, a big customer dimension with rows in millions is big challenge to both modeler and ETL loader. Customer duplication in customer dimension can become the worst performance bottleneck. Dedupe process could be very time consuming, if possible, once duplicate data has been identified.

Identifying and eliminating duplicates in a database is a fundamental aspect of data management, crucial for maintaining data quality and upholding rigorous data governance standards. Duplicate data, if left unaddressed, can lead to a cascade of issues such as inaccuracies, inefficiencies, and increased operational costs.

Duplicate data is more than just an inconvenience; it's a significant barrier to effective data management and can have far-reaching implications. 1- Cost Implications: More duplicates mean more storage and maintenance requirements, directly impacting the bottom line. 2- Data Integrity Issues: Duplicates lead to inconsistent reporting and analysis, compromising the reliability of data-driven decisions. 3- Customer Experience: In customer-facing systems, duplicates can result in poor customer experiences and communication errors. It's crucial for organizations to invest in robust data cleaning and deduplication processes to maintain the integrity and reliability of their data assets.

If the data is in multiple places and an exact match, your problem is when you're counting. If you don't realize the issue and pick them all, your counts will be wrong. The bigger issue tends to be when the data is in multiple places and it's not an exact match. If you realize that is happening, then you have to know which version to look at. If you don't pick the right one, your results will be impacted. If you don't realize there are multiple versions, your results will be impacted unless you get lucky and choose the right version.

It is always tricky to identify the duplicates as few of them are not exact match. In order to add efficiency in finding duplicates, fuzzy matching logic should be used. Most of the data profiling or integration tools provide variety of matching mechanisms, that would yield more duplicates. We may have to standard the data before running into matching for identifying duplicates.

The journey toward a deduplicated database begins with data profiling. This initial step involves a comprehensive examination of the data's structure, content, and characteristics. Data profiling tools are instrumental in uncovering patterns, identifying anomalies, and highlighting potential duplicates. This deep dive provides essential insights that serve as the foundation for subsequent deduplication efforts.

Identifying duplicates is a critical first step in ensuring data integrity. Here's a quick breakdown: 1- Basic Tools: Utilize Excel, SQL, Python, or R for basic duplicate identification. Functions like 'DISTINCT' in SQL or 'drop_duplicates()' in Python are handy. 2- Data Quality Software: For more complex datasets, specialized tools can automate the process, offering advanced profiling and matching capabilities. 3- Visualization: Tools like Tableau or Power BI can visually represent duplicates, making it easier to spot patterns or outliers. Each method has its place depending on the data's complexity and the resources available. It's about choosing the right tool for the job!

Power Query in both Power BI and Microsoft Excel can identify the number of duplicates, keep the duplicate rows only so that you confirm what they are, and then deal with them as you deem fit.

Sophisticated MDM tools like Reltio can handle matching, merging, and de-duplication as part of the product's capabilities. The classic approach to this problem was to write many matching rules (ex., If name and address are the same, then merge it’s the same person); sometimes rules could become very complex. ML can be a great help in such a task. One of the approaches, in this case, is Active Learning, where human inputs are used to actively retrain models after each answer, which could dramatically reduce the need for an extensive training corpus. Some of this is covered in the blog : https://www.telm.ai/blog/leveraging-ml-to-supercharge-data-quality-validation-processes/

Identified duplicate records should be matched and merged. Eliminating the duplicate records are not straight forward, as each record in the cluster may have valid values that are required for surviving record. Duplicate records do not mean always 2 records, it may mean more than that. Consolidating and merging the duplicate records should need business and data owners approval.

With a well-profiled, standardized dataset in hand, organizations can employ record linkage techniques to identify duplicates effectively. These techniques encompass various methodologies, including exact matching, fuzzy matching, and phonetic matching. Exact matching involves comparing all fields within records for identical values. In contrast, fuzzy matching detects similar records, even when values aren't exact matches. This proves invaluable in identifying duplicates with slight variations, such as misspelled names or inconsistent addresses.

Eliminating duplicates is crucial for maintaining data quality. Here's a concise strategy: 1- Deletion: For exact duplicates, use data management tools or programming languages to delete them. 2- Merging/Consolidation: For partial duplicates, merging records is key. Use data quality tools to combine these records, ensuring no valuable information is lost. 3- Flagging for Reference: If duplicates need to be retained for audit or reference purposes, flag them using visualization tools. This helps in distinguishing them from unique records. Each method has its place and choosing the right one depends on the specific needs and context of your data.

Preventing duplicate data is essential for maintaining long-term data integrity. Here's a succinct strategy: 1- Data Governance: Implement robust data governance policies. Define clear rules for data creation, collection, storage, and updates. This ensures consistency and quality across the board. 2- Data Entry and Validation: Strengthen data entry processes. Incorporate checks and validation to minimize human errors. 3- Data Integration: Enhance how data from various sources is integrated and synchronized. This reduces the chances of system-related duplications. By focusing on these areas, organizations can significantly reduce the occurrence of duplicate data, leading to more reliable and actionable insights.

Have a proper validation at each data entry points would prevent duplicate records. If bulk load is planned, have a procedure to profile before loading into the system. Run the data profiles regularly to identify the duplicates. Database level constraints to have unique values on columns would also prevent the occurrence of duplicates.