Manage Duplicate Records

Last Updated 1/26/2023

INTRODUCTION

Duplicate records in a database can create serious problems and harm your business if not managed properly. Data deduplication is a process involving procedures and techniques that removes duplicate records in a data table. Organizations can benefit from removing and merging duplicate records in many ways and avoid potential problems and related costs.

The presence of duplicates can have a number of negative impacts on a business or organization. For example, they can lead to confusion and errors when trying to access or update information, and they can skew analytics and reporting. Additionally, duplicates can lead to wasted storage space and increased costs for maintaining the database or system.

DATA TABLES

There are few data table types and each type requires a different approach regarding data deduplication. Master and transaction data tables are very common and most likely to be part of a database schema:

• Master data table - tables used to maintain records like customers, products and other items. Data in master tables seldom changes. For example, a customer table may have fields like name and address of the customer that may change once in a while as well as other fields that are permanent including customer identifier as primary key. Master tables are subject to updates and inserts. Deleting from master table is not a good practice and it is always better to deactivate records. Deleting records from master tables should be done using a procedure that validates the delete action.
• Transaction data table - tables driven by a date field, one or more quantitative fields and many relations to master tables. For example, sales header and detail tables are transactions tables. When it comes to record operations, ideally only inserts should be used in transactions tables while updates and deletes should follow special procedures.

Eliminating data duplicates can be addressed by looking at what's causing duplicate data in the first place. Data editing and new additions, in record operations named updates and inserts, can cause duplicates. Removing data or deleting records doesn't create duplicates; however, in most situations deleting data is not recommended and sometimes not even possible in Relational Database Management Systems (RDBMS).

In terms of operations data duplicates are caused by data entry, both new record addition and editing and bulk imports.

SCENARIOS

Avoiding duplicate data should be at the top of the list while creating a database and duplicates prevention procedures should be implemented from the beginning. Unique indexes for one or more columns are an easy way to prevent duplicates. Most database systems allow such indexing and creating indexes should be part of designing master tables. For example, a Departments master table may have unique indexes for Department Name and Department Code. Business rules will drive the unique index requirement and implementation.

In some situations, master tables can have columns where duplicate data can be entered; however, some entries are not considered duplicates while others will be considered duplicates. For example, Contact Name in a Contacts table may have duplicate entries that are allowed because different contacts have same name and, in this situation, additional columns are involved in defining the unique record. The downside is that all fields are required when the record is created and sometimes such constraints can delay data acquisition process.

A third scenario when it comes to duplicate data is when data entered is not the same; however, it is considered duplicate and a unique index doesn't catch the duplicate. Different data strings with same meaning represents a complicated situation and master tables have to be analyzed for this possibility. For example, scallion and green onion are same ingredient spelled differently on multiple records in an Ingredients master table and additional unique columns are difficult to implement.

HOW TO PREVENT DUPLICATES

To prevent duplicates, it is important to have a system in place to detect and remove them. One approach is to use duplicate detection software, which compares records and identifies those that are the same. Another approach is to use data validation rules, which ensure that each record is unique before it is entered into the system.

Another important step is to have a clear process in place for managing and updating records. This can help to reduce the chances of duplicates occurring and make it easier to identify and remove them when they do.

Another effective way to prevent records duplicates is to use duplicate detection software. This type of software can scan through a database and identify duplicate records, allowing them to be easily merged or deleted.

In addition, regular data cleaning and deduplication process should be implemented to minimize the number of duplicate records.

CONCLUSION

Overall, records duplicates can be a major problem for any database or record-keeping system. By implementing strict data entry protocols, using duplicate detection software, and regularly cleaning and deduplicating the data, it is possible to minimize the risk of duplicates and ensure that the information in the system is accurate and reliable.

However, even with the best practices in place, duplicates may still occur. In these cases, organizations should have processes in place for identifying and resolving duplicates, such as:

• Regularly running deduplication reports
• Assigning a dedicated team or individual to review and resolve duplicates
• Implementing a rule to determine which version of a duplicate record should be kept
• Updating all relevant systems and databases when duplicates are resolved

In conclusion, records duplicates can have a detrimental impact on businesses and organizations. To minimize the occurrence of duplicates, organizations should implement best practices for data entry, management, and deduplication, and have processes in place for identifying and resolving duplicates when they do occur.