I want to add a new column to my production database. I would like to add a default value in order to prevent all the
if not null and ... business in all my queries (both new and old).
What order of
add column-time penalty will I pay? I would ASSUME and HOPE that MySql would be smart enough to not actually fill in the default values for all the old rows, and instead treat the NULL value as the default (in other words, internalize the "if not null..." into the query automatically). ... and thus there should be NO penalty over and above the normal column add.
To be explicit, here are the two different MySQL alter table commands: in 5.1, is there any difference in the time efficiency of the two commands?
alter table XYZ add column newcol int ;
alter table XYZ add column newcol int default 0;
I assume that the answer would be version-specific. Am doing this in AWS EC2-land. Here's the version string:
mysql Ver 14.14 Distrib 5.1.73, for redhat-linux-gnu (x86_64) using readline 5.1