Joinmerge

Joinmerge is a data processing operation that combines two or more datasets by aligning records on one or more join keys and merging the resulting attributes into a single record. It is used in data integration tasks where records from different sources describe the same entity but carry different attributes.

In a typical joinmerge workflow, a join strategy (inner, left, right, or full outer) is selected to pair rows by key, the datasets are joined, and a merge policy is applied to reconcile overlapping fields. Merge policies may include taking the non-null value, coalescing values, prioritizing attributes from a preferred source, or applying custom conflict-resolution logic. When fields contain complex types, such as arrays or maps, the merge step may combine or deduplicate these structures.

Variants include join-then-merge, common in ETL pipelines, and streaming joinmerge for real-time data fusion. Some architectures separate join and merge into distinct stages for clarity and scalability.

Implementation is common in relational databases via outer joins and coalesce functions, and in data processing frameworks by defining schemas and applying user-defined merge rules.

Applications include master data management, customer data integration, product catalog consolidation, and data warehouse enrichment.

Limitations involve potential information loss if merge policies are overly aggressive, handling of duplicates, performance with large datasets, and the need for clear provenance and auditability.

See also: join, merge, data fusion, ETL, master data management.