It's probably easy to do if you know it's an issue to begin with. I've run into this scenario before (running sql queries to read data that turned out to lock e

It's probably easy to do if you know it's an issue to begin with. I've run into this scenario before (running sql queries to read data that turned out to lock everything) and it caught me by surprise. Why would a read query cause the database to lock anything? I thought databases did stuff like multiversion concurrency control to make locks like that unnecessary.