Add Column using Doctrine to live site

I'm about to push a site I've been develop开发者_StackOverflowing using Code Igniter and Doctrine live.

I want to push it live in it's current state, but know I'll be adding features in the future that might require changing columns, changing enum values, and adding columns to my doctrine records.

Up to now I've been just dropping tables and recreating them using:

Doctrine::createTablesFromModels();

Obviously this isn't possible one the database starts filling up with live data. How can I add and alter the columns without dropping and recreating the tables from models each time?

Many thanks.

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Use Migrations