How to Resolve "Deadlock Found When Trying to Get Lock" in MySQL
Two transactions each hold a lock the other one needs, and MySQL detects the standoff and kills one of them rather than letting both wait forever. A deadlock...
Category
MySQL
Fixes for connection limits, query performance, and encoding issues in MySQL.
How to Fix "Table Is Marked as Crashed and Should Be Repaired" in MySQL
A query against a table that was working fine suddenly fails, and MySQL reports the table itself is corrupted. This error is specific to the older MyISAM...
How to Resolve "MySQL Slow Query Log Not Recording Queries"
You've enabled MySQL's slow query log expecting to catch problematic queries, but the log file stays empty even though you know slow queries are happening....
How to Fix "Error 1054 (42S22): Unknown Column in Field List"
A query fails claiming a column doesn't exist, even though you're confident it's really there. This error means MySQL parsed your query successfully but...
MySQL Column Default Value Expression Invalid Error After Migration
An "invalid default value" error after a migration usually means either your MySQL version's rules around what counts as a valid column default changed, or the...
MySQL "Deadlock Found When Trying to Get Lock; Try Restarting Transaction" on Concurrent INSERTS
Deadlocks between concurrent INSERT statements specifically (rather than mixed read/write or UPDATE-heavy workloads) have their own distinct cause — InnoDB's...
MySQL GROUP BY Clause Failing With ONLY_FULL_GROUP_BY Enabled
ONLY_FULL_GROUP_BY, enabled by default since MySQL 5.7, enforces the SQL standard requirement that any column selected without being wrapped in an aggregate...
MySQL max_allowed_packet Size Exceeded on BLOB/TEXT Data
Large BLOB/TEXT data specifically tends to hit max_allowed_packet limits more often than typical row data, simply because these column types are exactly the...
MySQL "Too Many Connections," Accessing via the Dedicated Admin Port
MySQL 8.0.14 and later support a dedicated administrative connection port (extra_port), specifically designed to let a database administrator connect and...