Sync MySQL Time

Luke Hebert

January 24, 2022 - 2 minutes read - 223 words

If your application logs show timestamps that do not line up with the server clock, the culprit is often a stale MySQL time reference. The fix is straightforward: confirm the mismatch, restart the service, and verify the correction.

Why This Happens

MySQL reads the system clock at startup and caches the timezone offset. If the host clock drifts, is manually adjusted, or the timezone configuration changes while MySQL is running, the database will keep reporting the old time until it is restarted.

Steps

Check the system date.
```
date
```
Check what MySQL reports.
```
SELECT NOW();
```
Compare the two values. If they differ by more than a few seconds, proceed.
Restart the MySQL service.
```
sudo systemctl restart mysql
```
On systems that use the older service manager:
```
sudo service mysql restart
```
Verify the fix.
```
SELECT NOW();
```
The returned timestamp should now match the output of date on the host.

A Few Things to Keep in Mind

Note

Restarting MySQL will briefly interrupt all active connections. Schedule the restart during a maintenance window if the instance is in production.

If the mismatch persists after a restart, double-check the default-time-zone setting in your MySQL configuration file (/etc/mysql/mysql.conf.d/mysqld.cnf or /etc/my.cnf).
For long-running hosts, consider enabling ntpd or chronyd so the system clock stays accurate and the mismatch never builds up in the first place.

SysAdmin