[postgresql] What does it mean when a PostgreSQL process is "idle in transaction"?

What does it mean when a PostgreSQL process is "idle in transaction"?

On a server that I'm looking at, the output of "ps ax | grep postgres" I see 9 PostgreSQL processes that look like the following:

postgres: user db 127.0.0.1(55658) idle in transaction

Does this mean that some of the processes are hung, waiting for a transaction to be committed? Any pointers to relevant documentation are appreciated.

As mentioned here: Re: BUG #4243: Idle in transaction it is probably best to check your pg_locks table to see what is being locked and that might give you a better clue where the problem lies.