MySQL TEXT field performance
I have several TEXT and/or MEDIUMTEXT fields in each of our 1000 MySQL tables.  I now know that TEXT fields are written to disk rather than in memory when queried.  Is that also true even if that field is not called in the query?  For example, if I have a table (tbExam) with 2 fields (id int(11) and comment text) and I run SELECT id FROM tbExam, does MySQL still have to write that to disk before returning results or will it run that query in memory?

I am trying to figure out if I need to reconfigure our actual db tables to switch to varchar(xxxx) or keep the text fields and reconfigure the queries.
MySQL TEXT field performance
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I have several TEXT and/or MEDIUMTEXT fields in each of our 1000 MySQL tables.  I now know that TEXT fields are written to disk rather than in memory when queried.  Is that also true even if that field is not called in the query?  For example, if I have a table (tbExam) with 2 fields (id int(11) and comment text) and I run SELECT id FROM tbExam, does MySQL still have to write that to disk before returning results or will it run that query in memory?

I am trying to figure out if I need to reconfigure our actual db tables to switch to varchar(xxxx) or keep the text fields and reconfigure the queries.