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MongoDB System Alert: The SQL Interface May Omit Results When Using LEFT or RIGHT JOINs (SQL-3465)

MongoDB SQL Interface issue may cause LEFT or RIGHT JOIN queries to omit results when join keys are NULL or MISSING.

Written by Joao Maciel

Issue Description

Date announced: November 6, 2026

We have identified a critical issue affecting the SQL Interface (Atlas and Enterprise Advanced). The issue can produce incorrect results for SQL queries with a LEFT or RIGHT JOIN when the join keys may evaluate to UNKNOWN.

This issue affects the following tools and products:

  • SQL Interface (Atlas and Enterprise Advanced)

  • JDBC 3.0.8 and earlier versions

  • ODBC 2.0.10 and earlier versions

  • MongoSQL versions between 1.1.0 and 1.8.7 (deployed on Atlas Data Federation)

Customers using the legacy BI Connector are not impacted.

What Is the Impact?

When a query meets the criteria below, qualifying rows may be omitted from its results. This can lead to incorrect result sets for SQL queries.

Am I Impacted by This Issue?

This issue only occurs for a query if ALL the following are true:

  1. The query contains a LEFT or RIGHT JOIN with a single equality comparison condition between a field from the left datasource and a field from the right datasource.

    • For LEFT JOIN, the right datasource must be a collection.

    • For RIGHT JOIN, the left datasource must be a collection.

  2. The schema indicates that both fields in the condition may be UNKNOWN (NULL or MISSING).

  3. The left datasource (for LEFT JOIN) or the right datasource (for RIGHT JOIN) contains rows where the join key's value (field in the condition) is UNKNOWN.

Rows for which the above conditions are met will be omitted from the result set.

How Do I Remediate the Issue?

MongoDB Atlas Customers with Federated Databases

MongoDB has already upgraded the Atlas SQL Interface and quickstart SQL deployment to a version that addresses the issue. No further action is required.

Enterprise Advanced and Dedicated Atlas SQL Customers

The MongoDB JDBC driver version 4.0.0 and the MongoDB ODBC driver version 3.0.0 are available now and address the issue.

If your use case meets the criteria above, MongoDB recommends:

  • EA SQL and Dedicated Atlas SQL Interface users only

  • All users

    • Refresh impacted dashboards.

    • Update results by re-executing impacted SQL queries.

Additionally, MongoDB recommends that if customers are uncertain whether they meet all issue criteria, they should apply the same steps for any dashboard or SQL query using a LEFT or RIGHT JOIN.

For more information, see SQL-3465. If you have any questions, open a support case or start a chat with the MongoDB Support team.

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