Re: Understanding memory usage

Hello,

On Tue, Oct 29, 2013 at 12:23 AM, Daniele Varrazzo <
daniele(dot)varrazzo(at)gmail(dot)com> wrote:

>
> Because the result is returned to the client as the response for the
> query and is stored inside the cursor. fetch*() only return it to
> Python.
>

So why does calling "fetch*()" uses *additional* memory then? Does it copy
the data returned from the database?

By the way,* *I've re-run my tests but focused on the Vm*RSS* metric, which
represents how much actual physical memory is used by the process.

And I got the same behavior, that is almost no memory is reclaimed after
having fetched a *large* number of rows.
For instance, if I fetch 2 millions small rows, memory usage peaks around
500 MB and then only lowers to ~ 450 MB after data is freed.
On the other hand, fetching 100 large rows amounts to a 3 GB peak, which
subsequently falls back to 10 MB.

So is it a problem related to Psycopg itself or rather how Python handles
memory in general?

Regards,

--
Damiano Albani