March 04, 2025

Full Support for Flink SQL Joins in Streaming Mode

Avi Hadad
Avi Hadad
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Introduction

At Datorios, we are always pushing boundaries to empower real-time data processing at scale. Today, we are thrilled to announce a major milestone: full support for all types of joins in Flink SQL/Table API, in streaming mode!

Joins are a fundamental aspect of stream processing, allowing us to correlate, enrich, and analyze data across different sources. With this latest enhancement, users can now leverage a wide variety of streaming joins to build complex real-time applications with low latency and high efficiency.

What’s New?

We now support all join types in Flink’s SQL/Table API, enabling users to perform powerful and flexible data correlations. The diagram below illustrates the diverse set of joins now available in Datorios:

Key Join Types Explained:

  • Inner Join – Matches records with the same key in both streams. The classic join for correlated datasets;
  • Left Join – Keeps all records from the left stream, adding matches from the right stream when available;
  • Right Join – Keeps all records from the right stream, adding matches from the left stream when available;
  • Full Join – Keeps all records from both streams, filling in missing values where no match is found;
  • Lookup Join – Allows a stream to join with a dimension table for fast enrichment;
  • Window Join – Matches records within the same time window, ideal for time-sensitive correlations;
  • Interval Join – Extends window joins by allowing records to match across a time interval instead of a fixed window;
  • Temporal Join – Enables joins with changing reference data, like versioned tables or slowly changing dimensions;
  • Semi Join – A filter-like join that retains records from the left stream only when a match exists in the right stream;
  • Anti Join – The opposite of semi join; keeps records from the left stream only when there is no match in the right stream.

Observability is critical when running Flink SQL queries in production. Issues like slow queries, excessive state usage, and late events can impact performance. Datorios provides real-time insights into Flink SQL execution, allowing users to:

  • Detect bottlenecks in query performance.
  • Monitor state growth to avoid excessive memory usage.
  • Debug real-time data flow issues and optimize execution plans.

Datorios enhances Flink SQL workflows by providing:

  • Query Execution Analysis: Gain visibility into how SQL queries are processed in Flink, identifying inefficiencies and optimization opportunities.
  • State Management Insights: Understand how SQL-based stateful operations impact Flink performance, helping fine-tune memory usage.
  • End-to-End Query Tracing: Track how data flows through SQL queries, making it easier to debug complex stream-table joins.
  • Real-Time Alerts: Get notified about query slowdowns, late data arrivals, and processing anomalies before they affect downstream systems.

    By integrating Datorios, teams can confidently run Flink SQL queries at scale while maintaining operational quality.

Why Does This Matter?

With streaming joins, real-time applications can be more expressive, powerful, and efficient. You can now:

  • Enrich streaming data with fast lookups;
  • Correlate events from multiple sources in real time;
  • Handle time-based joins with windows and intervals;
  • Build dynamic applications that react instantly to data changes.

And much more!

Conclusion

This milestone represents a game-changing evolution in our mission to simplify and accelerate real-time data processing. By enabling full support for all streaming join types in Flink SQL/Table API, we are breaking down barriers for developers and data teams who need to process, enrich, and analyze data streams with unprecedented flexibility and efficiency.This is just the beginning. We are committed to continuous innovation, helping you harness the full potential of stream processing to drive your business forward. We can’t wait to see what you build with Datorios + Flink SQL/Table API!

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