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Description

This error occurs when a stored procedure or function recursively calls itself too many times, surpassing the maximum recursion depth defined by the `max_sp_recursion_depth` system variable. It typically indicates an issue with the routine's logic, such as an infinite loop or an unexpectedly deep recursion.

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Error Message

Recursive limit %d (as set by the max_sp_recursion_depth variable) was exceeded for routine %s

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Known Causes

3 known causes

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Infinite Recursion Loop

A stored procedure or function calls itself without a proper termination condition, leading to an endless loop that quickly exhausts the recursion limit.

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Insufficient Max Recursion Depth

The routine's legitimate logic requires a recursion depth greater than the currently configured `max_sp_recursion_depth` value, which might be set too low for the application's needs.

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Flawed Termination Logic

The base case or exit condition within the recursive routine is incorrectly implemented or unreachable, preventing the recursion from terminating as intended.

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Solutions

3 solutions available

1. Increase the Maximum Stored Procedure Recursion Depth easy

Temporarily or permanently increase the `max_sp_recursion_depth` server variable.

1

Connect to your MariaDB server using a client like `mysql` or `mariadb`.

mariadb -u your_user -p your_database

2

Check the current value of `max_sp_recursion_depth`.

SHOW VARIABLES LIKE 'max_sp_recursion_depth';

3

To temporarily increase the limit for the current session (until the server restarts), use the `SET SESSION` command. Replace `new_limit` with a sufficiently high value (e.g., 255, 512).

SET SESSION max_sp_recursion_depth = new_limit;

4

To permanently increase the limit, you need to modify the MariaDB configuration file (e.g., `my.cnf` or `mariadb.conf.d/50-server.cnf`). Add or modify the `max_sp_recursion_depth` setting under the `[mysqld]` section. Replace `new_limit` with your desired value.

[mysqld]
max_sp_recursion_depth = new_limit

5

After modifying the configuration file, restart the MariaDB service for the changes to take effect.

sudo systemctl restart mariadb

2. Refactor Recursive Stored Procedures advanced

Rewrite the stored procedure to avoid deep recursion by using iterative approaches or helper tables.

1

Analyze the stored procedure that is causing the recursion error. Identify the specific logic that leads to repeated calls of the same procedure or a chain of procedures calling each other.

N/A

2

Consider converting recursive logic to an iterative approach using loops (e.g., `WHILE` loops) and temporary tables or cursors to manage state. This is often more memory-efficient and avoids recursion limits.

Example (conceptual): Instead of calling a procedure recursively to process a tree, use a `WHILE` loop with a temporary table to hold nodes to be processed.

3

If the recursion is due to a complex hierarchical query, explore using Common Table Expressions (CTEs) with recursive clauses in newer MariaDB versions, which can be more performant and readable than manual recursion.

Example (conceptual CTE):
WITH RECURSIVE cte_name AS (
  SELECT initial_row FROM your_table WHERE ...
  UNION ALL
  SELECT t.* FROM your_table t JOIN cte_name ON t.parent_id = cte_name.id
)
SELECT * FROM cte_name;

4

Test the refactored procedure thoroughly to ensure it produces the correct results and handles edge cases.

N/A

3. Identify and Break Circular Dependencies medium

Examine the stored procedures and triggers to find and resolve any circular call chains.

1

List all stored procedures and triggers in your database. You can use the `INFORMATION_SCHEMA.ROUTINES` and `INFORMATION_SCHEMA.TRIGGERS` tables for this.

SELECT routine_name, routine_type FROM INFORMATION_SCHEMA.ROUTINES WHERE routine_schema = 'your_database_name';
SELECT trigger_name, event_object_schema, event_manipulation FROM INFORMATION_SCHEMA.TRIGGERS WHERE event_object_schema = 'your_database_name';

2

Manually review the code of the stored procedures and triggers identified in the error message. Look for patterns where Procedure A calls Procedure B, which in turn calls Procedure A (or a longer chain that eventually leads back to the starting procedure).

N/A

3

If a circular dependency is found, redesign the logic. This might involve introducing a flag or state variable to prevent repeated execution within the same call chain, or restructuring the tasks into a non-circular flow.

Example (conceptual flag):
IF @recursion_guard IS NULL THEN
  SET @recursion_guard = TRUE;
  -- Your recursive logic here
  -- ...
  SET @recursion_guard = NULL; -- Reset for other calls
END IF;

4

Consider if the circular dependency is truly necessary. Often, it indicates a design flaw that can be addressed by rethinking the workflow.

N/A

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Related Errors

5 related errors

MariaDB Error 1456: Recursive Limit Exceeded