I haven't been able to get any clear answer on this and it seems like a lot of very experienced people have different views on this. So the question is:
- I've made a setup install/update script + maybe some code dependent on what is configured there - like layout xml with attributes.
- I deploy it live on a heavy visited page
True or false:
- The first visitor will trigger and wait for all the scripts to run?
- Other visitors can visit the site meanwhile with old settings?
- Other visitors are just blocked until the scripts have run?
- Other visitors can use the site but what data they get is totally random depending on where in time it is.
- Layout xml can break if it is dependent on an attribute which isn't created (consider also flat tables)
- Magento clears out cache after setup scripts?