[support] impact of converting db varchars to integers

Hi, . To improve Drupal performance, our client has suggested to change the field types from varchars to integers in some tables.

A few tables with varchar fields are as follows:

node : type permissions : perm node_access : realm blocks_roles : module

(It means we are numbering node types from node/comment/page/story to 1/2/3/4..... like that)

I guess i need to change the drupal core code as well - if i change the core tables field types. I would like to know whether this is feasible or not.

And what would be the impact, if i change the data types of the core tables.

Thanks & Regards, T.Melantias