Mysql: Show all active transactions

Assuming INNODB:  Take a look at the INNODB_TRX Table in the docs:
https://dev.mysql.com/doc/refman/8.0/en/innodb-trx-table.html

The INNODB_TRX table providesinformation about every transaction (excluding read-onlytransactions) currently executing inside InnoDB, including whether the transaction iswaiting for a lock, when the transaction started, and the SQLstatement the transaction is executing, if any.

mytop is a handy tool, packaged for every Linux Distro.

This tool instantly shows long running SQL statements.

Likely there are Windows ports also, if you run Windows.

Hi,

You can also look at the threads by querying the INFORMATION_SCHEMA.PROCESSLIST table.

SELECT * FROM INFORMATION_SCHEMA.PROCESSLIST

Select allOpen in new window

and if you have the performance_schema turned on you could use that to query and investigate performance problems.

https://dev.mysql.com/doc/refman/8.0/en/performance-schema.html
https://dev.mysql.com/doc/refman/8.0/en/information-schema.html

Regards,
    Tomas Helgi

Show processlist

Show full processlist

I used to handle queries timeout through comments stuck in the query anx a small daemon

Wouldn't the processlist show connections not just transactions?

Yes, you'd need a trivial filter.

Innodb also has tools that display transactions in the engine but these require some parsing. Innotop gives a decent view of such transactions