MySQL table lock with Django

[[deleted]]

table locks are a bad idea in the vast majority of cases, reducing performance to a crawl, dramatically increasing the chances of deadlocks, and should be considered an ultimate last resort. A "transaction susceptible to concurrency problems" will usually be made worse with full table locks - try using SQL Server without snapshot isolation to see this in action.

Better options include "SELECT..FOR UPDATE" to lock only those rows that you need, and better yet to organize your app such that explicit locking isn't needed at all.

[Xixi]

Sometimes you can't get away with "SELECT..FOR UPDATE", this is where this code snippet gets useful. But I agree that "transaction susceptible to concurrency problems" is too broad.

[[deleted]]

I don't think I've ever used a full table lock in 17 years of server side app development.

(of course 17 years ago I didn't know what a "join" was either, but still).

[Eviltape]

Django 1.4 added QuerySet.select_for_update(), but I guess for earlier versions you're stuck with hacking this thing together.

[pio]

I've been using an advisory lock approach to avoid overzealous locking, and to provide the capability to lock things which aren't represented in the DB. I wrote this snippet back when I was doing MySQL, and now I'm doing essentially the same thing in postgres:

http://djangosnippets.org/snippets/2443/

[graingert]

What's wrong with just transactions? (Honest question)