strk <strk@keybit.net> writes:
> The size growth is reported by 'top' in the fields
> SIZE, RSS and SHARE.
> Can it be a memory leak in postgres code ?
No, you are misinterpreting the 'top' output.
You didn't say what platform you are on, but on some systems 'top'
increases the reported size of a backend process each time that process
touches a page of the shared memory area that it had not touched before.
In this case you are simply watching the process use shared buffers it
hadn't previously touched.
regards, tom lane