I do not think volcanic eruptions can change the course of the earth.

This is because whatever materials a volcano ejects ultimately land back to the ground, so the earth remains on its path. So no change in course/radius.

If, however, you can manage to create a blast which sends particles with such a force and such a speed that they never come back again (the speed will have to be $\geq 11.2 km/s$), then we can think about the change of course of the earth. Can Yellowstone do it?

But even if that DOES happen, the mass which it will be able to eject completely out of earth's gravitational field will be very less compared to the mass of the earth. So we can neglect and tiny change, since it's almost nothing. However, if a volcano could blast off even $1/10^{th}$s of the earth's mass, then we'd have some change in course/radius.



Addendum: I just thought of one thing though-
The material thrown up in a volcanic eruption emerges from inside the earth. When the eruption is over and the material is back on the ground, there has been a slight net displacement of the materials. What was first a few kilometres under the surface is now lying on the surface. Therefore, there may as well be a tiny change in course. 

HOWEVER, as pointed out before, the mass thrown up by a volcano is very very very less compared to the mass of the earth and the displacement of the material is very very less compared to the radius of the earth ($\approx 6400 km$), we can safely neglect this tiny change in course.
Even if there is a change, the radius of the earth's orbit around the sun is 150,000,000 km. A change in course by a fraction of a centimetre will make NO difference at all.



Addendum-2: Akash points out that the materials striking the ground don't apply the same force as the force at which the volcano erupts.   

That is not true. It may seem that the force is less, but that is because the materials are fragmented and a lot of the force is applied onto air too.
The force is distributed between all the particles and the air. When each particle strikes, it imparts its force to the earth. The air 'falls' back too, applying a force too. If you add up the forces, it will be equal to the force of the volcano.
Unless, of course, the materials are propelled out of the earth's gravitational field.

Do volcano blast changes earth's course?
I would like to store anonymous users $_SESSION in a cookie so that their cart and other custom information is still available even after closing the browser.

I found this interesting post which tells me I should add this to my local.settings.php:

ini_set('session.cookie_lifetime', 60 * 60 * 24 * 7);
ini_set('session.gc_maxlifetime', 60 * 60 * 24 * 7);
ini_set('session.save_path', '/home/yoursite/sessions');


So that session cookie would be available for a week.
But it also stands that we should use session_regenerate_id() elseway the cookie lifetime is not updated.

I could not find session_regenerate_idin Drupal 7 source code, but I believe Drupal might already handle this from what I read in the code comments.

My questions are:


is this a good approach to have persistent cookie sessions?
do I need to add to my local.settings.php session_regenerate_id() too?


Thank you very much for your advises
