A database administrator reported a strange issue: all queries, whether against system tables or business tables, returned the error 'Ignoring query to other database'. This article from the GreatSQL team walks through the debugging process. The error typically indicates that the MySQL client or server is in a state where it refuses to execute queries against a different database than the one currently selected. The article explores potential causes, such as a misconfigured default database, a corrupted connection state, or a bug in a specific MySQL version. It provides practical steps to diagnose the issue, including checking the current database context, verifying user permissions, and examining server logs. The resolution often involves resetting the connection or correcting the database selection. This case is valuable for DBAs and backend engineers who might encounter similar cryptic errors, as it demonstrates a systematic approach to troubleshooting database connectivity and state issues.
A real-world debugging case study on a MySQL error that caused all queries to be ignored, with root cause analysis and resolution steps.