This ensures most of the rest goes without error first
Disable triggers on the table before doing update
This speeds the update up significantly as we don't need to re-calc the
additional column's new data.
Allow new column to be null (at first) with no default
This allows the column to be added *without* re-writing every row. We still
re-write every row with the update, but at least we aren't doing that
*twice* this way.
And add the not null/default to new column and re-enable triggers as our
last action.
Signed-off-by: Thomas Berezansky <tsbere@mvlc.org> Signed-off-by: Jason Stephenson <jstephenson@mvlc.org>