Way to know what is locked in the db and what query is locking it?

[Matias Burak]

Hi guys we are running in some situations where we see that a node is locked... we cannot write into it, it hangs when we do that from shell. 

Also we often see that something looks like locked but we don't know what.

 

Is there any query or something we can do to see what's going on?

Thanks,

Matias.