One of the biggest complaints I have heard about MySQL is that it locks up a table if you try to change its schema like adding a column or adding an index.

By "locking up the table" does it mean I can neither read nor write to the table? Sometimes for hours?

That seems a pretty severe limitations. I was going to use MySQL for my new project but this gives me pause.

Is there a workaround for this? How do you handle the task of changing the schema of your production MySQL database?

By the way someone told me Postgresql doesn't have this problem. Is that true - I can both read and write to a Postgresql table while changing its schema? Is there any performance penalty incurred?

Would love to hear your experiences.