Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
> It seems possible to change some DDL commands/subcommands to use a
> ShareLock rather than an AccessExclusiveLock. Enclosed patch implements
> this reduction for CREATE TRIGGER, CREATE RULE and ALTER TABLE.
What happens when two transactions try to do one of these things
concurrently to the same table?
regards, tom lane