I've encountered this exact scenario in production environments where auto-increment IDs mysteriously reset. The behavior typically manifests when:

• The table becomes completely empty (TRUNCATE operations)
• Server restarts occur with specific storage engines
• ALTER TABLE operations modify the auto-increment column

InnoDB handles auto-increment differently than MyISAM:

-- InnoDB behavior
CREATE TABLE jobs_innodb (
    id INT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY,
    job_data TEXT
) ENGINE=InnoDB;

-- MyISAM behavior  
CREATE TABLE jobs_myisam (
    id INT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY,
    job_data TEXT
) ENGINE=MyISAM;

InnoDB doesn't persist the auto-increment counter to disk between restarts, while MyISAM does. This explains why you might see resets after server reboots.

Based on my troubleshooting experience, these operations frequently cause the issue:

-- Dangerous operation that resets counter
TRUNCATE TABLE jobs;

-- Safe alternative that preserves auto-increment
DELETE FROM jobs;
ALTER TABLE jobs AUTO_INCREMENT = 1;

Here are robust approaches I've implemented successfully:

Option 1: Lock the Auto-increment Value

-- Set an arbitrarily high value that won't be reached
ALTER TABLE jobs AUTO_INCREMENT = 10000000;

Option 2: Use Application-level Sequencing

// PHP example using external sequence table
$stmt = $pdo->prepare("
    UPDATE job_sequences 
    SET next_id = LAST_INSERT_ID(next_id + 1) 
    WHERE table_name = 'jobs'
");
$stmt->execute();
$newId = $pdo->lastInsertId();

Option 3: Switch to UUIDs

-- Complete solution without auto-increment
CREATE TABLE jobs_uuid (
    id CHAR(36) NOT NULL PRIMARY KEY DEFAULT (UUID()),
    job_data TEXT
);

Implement this trigger to log auto-increment changes:

DELIMITER //
CREATE TRIGGER log_autoinc_change
BEFORE INSERT ON jobs
FOR EACH ROW
BEGIN
    DECLARE current_autoinc INT;
    SELECT AUTO_INCREMENT INTO current_autoinc
    FROM information_schema.TABLES
    WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = 'jobs';
    
    INSERT INTO autoinc_audit (table_name, autoinc_value, changed_at)
    VALUES ('jobs', current_autoinc, NOW());
END//
DELIMITER ;

Run this query periodically to monitor auto-increment behavior:

SELECT 
    TABLE_NAME,
    AUTO_INCREMENT,
    UPDATE_TIME
FROM information_schema.TABLES
WHERE TABLE_SCHEMA = 'your_database';

---

I've encountered this exact issue in production environments where job queue tables exhibit strange auto-increment behavior. The auto-increment value (AUTO_INCREMENT) in MySQL can indeed reset under specific circumstances, though it's not documented behavior.

From my experience, these are the most common triggers:

-- Scenario 1: Table truncation
TRUNCATE TABLE job_queue;  -- This WILL reset auto-increment

-- Scenario 2: Server restart with empty table
-- If the table is empty when MySQL restarts,
-- some storage engines may reset the counter

The behavior varies by storage engine:

• InnoDB: Persists the counter in memory but may lose it on restart
• MyISAM: Stores counter more persistently in .MYI files

Here are proven solutions I've implemented:

Solution 1: Change the Table Definition

ALTER TABLE job_queue AUTO_INCREMENT = 1000000;
-- Set it high enough to avoid conflicts

Solution 2: Use BIGINT Instead

ALTER TABLE job_queue 
MODIFY COLUMN id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT;

Solution 3: Custom Sequence Table

CREATE TABLE sequence (
    name VARCHAR(64) PRIMARY KEY,
    value BIGINT UNSIGNED NOT NULL
);

-- Transactional increment
START TRANSACTION;
INSERT INTO sequence VALUES ('job_id', 1) 
ON DUPLICATE KEY UPDATE value = value + 1;
SELECT value FROM sequence WHERE name = 'job_id' FOR UPDATE;
COMMIT;

Create a monitoring script to alert on counter resets:

SELECT 
    TABLE_NAME,
    AUTO_INCREMENT,
    TABLE_ROWS 
FROM 
    INFORMATION_SCHEMA.TABLES 
WHERE 
    TABLE_SCHEMA = 'your_db'
    AND TABLE_NAME = 'job_queue';

Unexpected ID resets can cause:

• Duplicate key errors if old records aren't purged
• Broken job tracking systems
• Data integrity issues in reporting