MySQL troubleshooting

This troubleshooting section describes the common pitfalls and errors around configuring, linking, and provisioning MySQL datasets and provides possible solutions. This section explains the following in detail:

Connector logs and the path at which these logs are generated. These logs contain information regarding the flow of events, failure regarding any MySQL command failures, trace messages, etc.
Common MySQL commands. These commands will help you understand how to check replication status, user permissions, etc
Exit Codes and actions that users can take in case of any error.
Version compatibility. This guides the user to upgrade from MySQL version 5.7 to 8.

If the user is still not able to resolve the error, please reach out to Delphix Support.

Logs

There are 2 sets of logs for the MySQL plugin:

Plugin Logs: Plugin logs are part of the Delphix Continuous Data Engine. Refer to How to Retrieve Logs to find out how to get the Delphix Continuous Data Engine Plugin Logs.
MySQL Shell Operation Logs: When the plugin performs certain operations (such as Take backup, Link, Provision, etc.), logs are written to log files on the staging or target host under the Delphix Continuous Data Engine Toolkit directory.

Following are the logs to review:

delphix_mysql_user_mysql_debug.log
delphix_mysql_user_mysql_info.log
delphix_mysql_user_mysql_error.log

Common MySQL commands

Connecting to a MySQL instance

CODE

delphixos> /usr/bin/mysql -u UserName -p Password --protocol=TCP --port=1234

List databases in MySQL
CODE
```
mysql> show databases;
```
Check the replication status in MySQL
CODE
```
mysql> show replica status;
```
Check binary logging
CODE
```
mysql> show variables like 'log_bin';
```
Check user permissions
CODE
```
mysql> show grants for 'delphixdb'@'%';
```

MySQL Plugin exit codes

The below tables include exit codes that the MySQL connector (plugin) presents if an error occurs.

Exit Code	Description	Possible Reason
1	General Error	Check logs
2	General Error	Check logs
3	Unable to start MySQL	Delphix user does not have the necessary permissions on the host Mount location provided is in use Database credentials provided are not accurate Invalid server-id Provided port is not in use
4	Missing config file	A `my.cnf` file was not provided and Delphix was unable to create one.
5	Unable to change `root` password	Delphix was unable to change the password for the root user after creating the staging db. Please check logs.
6	Unable to restore backup	Delphix was unable to restore the full backup into staging db. Please check logs.
7	Connect failure post restore	Delphix is unable to connect to the staging database after backup is restored. The Source DB username and password provided may be incorrect. The MySQL Database did not restart after the restore. Check logs for more information on the error.
8	Delphix backup failure	Delphix could not take a source database backup. Staging Host may not be able to connect to Source Host Source DB credentials may be incorrect Source DB user may not have the required permissions Databases provided in the list may not be present on the source MySQL instance. Check logs for more information on the error.
9	Customer backup failure	There was an issue with the customer provided backup. Backup location may not exist. The backup file may not exist Backup file may be empty. Check logs for more information on the error.
10	Invalid binary path	`mysql` was not found under the provided installation directory.
11	Connect failure after restart	In Staging Push Mode, the Delphix source user could not connect to the MySQL instance after reboot. Check logs for more information on the error.
12	Unable to create user	In Staging Push Mode(Staging Push), there was an error while creating the delphix user after staging db was initialized. Check logs for more information on the error.
13	An error occurred while starting replication	Check the provided credentials if they are valid
14	An error occurred while granting the permissions	Check the logs for more information, permission error for performing operation. Try creating dSource again.
15	An error occurred while starting replication	The user has selected to provide a different replication user and password but the provided replication user or password is empty

Version compatibility

The MySQL connector requires that the staging and target environment’s MySQL major versions match. This also means that any snapshot’s MySQL version must match the installation on the Target environment. This applies to all VDB operations, such as provision, rollback, and refresh. The operation will fail if the two versions are different, such as MySQL v5.7 on Staging and v8 on Target.

MySQL, unlike other databases, does not support automatic upgrades.

Guidance on how to upgrade your staging environments, target environments, and VDBs can be found in the Upgrading dSources and VDBs MySQL database versions section.

In version 4.1.0 of the MySQL connector, we have introduced guardrails to minimize accidentally broken VDBs when refreshing from a lower versioned dSource. A sample screenshot can be seen below.