ksqlDB 0.19.0 adds support for foreign-key joins between tables. Data decomposition into multiple tables (i.e., schema normalization) is a key strength of the relational data model and often requires joining tables based on a foreign key. So far, we have been able to provide tools for normalizing data, provided the rows in each of the tables followed a one-to-one relationship (i.e., have the same primary key).
Providing built-in support for foreign-key joins, which was previously only possible to do through workarounds, unlocks many new use cases where you’d like to have a many-to-one relationship between your tables. This is a highly demanded feature, and we are excited to finally make it available.
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