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Description

This error occurs when attempting to add an `AUTO_INCREMENT` column to a MariaDB table via an `ALTER TABLE` statement. The operation fails because the database cannot acquire the necessary exclusive lock on the table. This typically happens when the table is actively being used by other transactions or queries, preventing the schema change.

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Error Message

Adding an auto-increment column requires a lock

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Known Causes

3 known causes

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Concurrent Transactions

Other active database sessions or transactions are currently reading from or writing to the target table, preventing an exclusive lock for the schema alteration.

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Long-Running Queries

Existing long-running queries or operations on the table are holding locks, making it impossible to acquire an exclusive lock required for the `ALTER TABLE` statement.

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Explicit Table Locks

Another database session might have explicitly locked the table using commands like `LOCK TABLES`, preventing any other session from acquiring an exclusive lock for schema modifications.

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Solutions

3 solutions available

1. Add Auto-Increment Column with Minimal Locking medium

Alter table in a way that minimizes the duration of the lock required.

1

Create a new table with the desired structure, including the auto-increment column.

CREATE TABLE new_table LIKE original_table;
ALTER TABLE new_table ADD COLUMN new_auto_increment_column INT AUTO_INCREMENT PRIMARY KEY FIRST;
-- Adjust column order as needed and add other columns from original_table.

2

Copy data from the original table to the new table.

INSERT INTO new_table (column1, column2, ...) SELECT column1, column2, ... FROM original_table;

3

Rename the original table to a backup name.

RENAME TABLE original_table TO original_table_backup;

4

Rename the new table to the original table's name.

RENAME TABLE new_table TO original_table;

5

Verify the data and structure of the new `original_table`.

DESCRIBE original_table;
SELECT COUNT(*) FROM original_table;

6

Once confirmed, drop the backup table.

DROP TABLE original_table_backup;

2. Schedule the Alter Operation During Low Traffic easy

Perform the schema change when database activity is minimal to avoid blocking other operations.

1

Identify a period of low database activity (e.g., overnight, weekend).

2

Execute the `ALTER TABLE` statement to add the auto-increment column during this low-traffic window.

ALTER TABLE your_table ADD COLUMN new_auto_increment_column INT AUTO_INCREMENT PRIMARY KEY FIRST;
-- Adjust column order and constraints as needed.

3

Monitor the database performance and application responsiveness during and after the change.

3. Restart MariaDB Service (Caution Advised) medium

A full server restart can sometimes clear transient locking issues, but this is a disruptive approach.

1

Ensure all critical operations are completed and backups are taken.

2

Gracefully stop the MariaDB service.

sudo systemctl stop mariadb

3

Start the MariaDB service.

sudo systemctl start mariadb

4

Attempt to add the auto-increment column again. If the error persists, this solution was not effective for the underlying cause.

ALTER TABLE your_table ADD COLUMN new_auto_increment_column INT AUTO_INCREMENT PRIMARY KEY FIRST;

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Related Errors

5 related errors

MariaDB Error 1854: Adding Auto-Increment Needs Lock