High Performance PostgreSQL for Rails

Using Direct Updates for Text Replacement

Direct updates are the alternative strategy that offer good-enough performance and much less complexity.

This strategy is “destructive” compared with clone and replace, because it mutates the table row data in place. Clone and replace has a “rollback” benefit because you’ve got the option before the table name swap, where both tables exist, and you can do checks to make sure everything is good before swapping. That’s an important benefit that you’ll lose with this strategy.

Let’s try it out. Run the following UPDATE statement from psql to scrub email address columns for every row. You may want to reset all the way back to start from the “sensitive” fake generated values, or you may want to mutate the ...