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Description

This error indicates that a recursive Common Table Expression (CTE) in your MySQL query has exceeded the maximum allowed recursion depth. It occurs when a recursive query either enters an infinite loop or legitimately requires more iterations than the `@@cte_max_recursion_depth` system variable is currently configured for.

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Error Message

Recursive query aborted after %u iterations. Try increasing @@cte_max_recursion_depth to a larger value.

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Known Causes

3 known causes

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Infinite Loop in Recursive CTE

The logic within your recursive CTE lacks a proper termination condition or contains a flaw that causes it to run indefinitely.

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Insufficient Recursion Depth Limit

The `@@cte_max_recursion_depth` system variable is set too low for the legitimate depth required by your recursive query.

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Complex Data Hierarchy

The data structure being queried is naturally very deep, causing the recursive CTE to legitimately require many iterations that exceed the default or current limit.

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Solutions

3 solutions available

1. Temporarily Increase Recursion Depth easy

Adjust the `cte_max_recursion_depth` variable for the current session.

1

Connect to your MySQL server using a client like `mysql` CLI, MySQL Workbench, or any other tool.

2

Before executing your recursive CTE query, set the `cte_max_recursion_depth` session variable to a higher value. A good starting point is 1000 or 2000, but you might need to experiment based on your data and query complexity.

SET SESSION cte_max_recursion_depth = 2000;

3

Execute your recursive CTE query immediately after setting the session variable.

-- Your recursive CTE query goes here --
WITH RECURSIVE cte_name AS (
    -- Anchor member
    SELECT ...
    UNION ALL
    -- Recursive member
    SELECT ... FROM cte_name WHERE ...
)
SELECT * FROM cte_name;

4

Note that this change only affects the current session. It will revert to the default value (or a previously set global value) when the session ends.

2. Globally Increase Recursion Depth medium

Modify the `cte_max_recursion_depth` server-wide for a persistent change.

1

Connect to your MySQL server as a user with `SUPER` or `SYSTEM_VARIABLES_ADMIN` privileges.

2

Set the `cte_max_recursion_depth` variable globally. The default is often 1000. Choose a value that should accommodate most of your recursive queries. Be cautious not to set it excessively high, as it can consume significant memory.

SET GLOBAL cte_max_recursion_depth = 5000; -- Example: set to 5000

3

To make this change permanent across MySQL server restarts, you need to update the MySQL configuration file (e.g., `my.cnf` or `my.ini`). Locate the `[mysqld]` section and add or modify the `cte_max_recursion_depth` parameter.

[mysqld]
cte_max_recursion_depth = 5000

4

After modifying the configuration file, restart your MySQL server for the global setting to take effect.

sudo systemctl restart mysql # or equivalent command for your OS

3. Optimize Recursive CTE Logic advanced

Refactor the query to reduce the number of recursive iterations.

1

Analyze the recursive CTE query to understand its logic and how it generates new rows in each iteration. Identify the termination condition and the data being processed.

2

Look for opportunities to prune irrelevant data early in the recursion. Can you add `WHERE` clauses in the recursive member to filter out rows that won't contribute to the final result?

-- Example: Adding a WHERE clause to the recursive member --
WITH RECURSIVE cte_name AS (
    SELECT ...
    UNION ALL
    SELECT ... FROM cte_name WHERE ... AND your_condition_here
)
SELECT * FROM cte_name;

3

Consider if the problem can be solved iteratively or with a different approach that doesn't require deep recursion. For example, if you're traversing a tree structure, you might be able to use a different algorithm or a pre-computed adjacency list.

4

Ensure that the base case (anchor member) is correctly defined and that the recursive step is making progress towards the termination condition. A common mistake is an infinite loop where the recursive member always generates new rows without meeting the termination condition.

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Related Errors

5 related errors

MySQL Error 3636: Recursive Query Depth Exceeded