Nine servers, one connection type, different answers
MariaDB, Percona, TiDB, Vitess and five more arrive through the same MySQL connection, and protocol compatibility is not capability compatibility.
8 posts
Writing on MySQL
Pooled connections with information_schema introspection, EXPLAIN plans, performance_schema-backed monitoring and agent mode under a principal verified to hold nothing past SELECT and SHOW VIEW. Where it stops: A transaction a script leaves open is not ended when its pooled connection is released, so it holds its row locks until the connection is reused or the pool closes. The one reliable check reads performance_schema, which is off by default on MariaDB.
With performance_schema off, MySQL metrics are absent not zero
Cache hit ratio, queries per second and buffer-pool usage are omitted rather than defaulted, and two more figures mean less than their names suggest.
Reading MySQL EXPLAIN FORMAT=JSON as a plan tree
What the plan tree answers on MySQL, and where the surrounding introspection runs out: index figures here are estimates of distinct values.
A MySQL ER diagram is bounded by one database
Every introspection query binds to the connected database, so a reference that crosses schemas simply does not appear as an edge on the diagram.
A MySQL connection URI skips your SSL and timezone settings
Supplying a connection string takes a different branch entirely, so the SSL panel, the timezone and cloud detection stop applying and must live in the URI.
Connecting to MySQL in a container, and what the pool honours
Port 3306 with the fixture credentials, the container-network case, and the pool settings that are quietly ignored because the driver model differs.
Stopping a runaway MySQL query is cancellation, not a timeout
No server-side statement timeout is wired into the pool, so nothing kills a long query on its own and cancellation is an explicit act with a caveat.
Agent plan mode on MySQL drafts; it does not execute
The tool-using run ends engine-unsupported here, so the useful post is what plan mode does instead: read the real schema and hand a statement to a person.