Re: locks in CREATE TRIGGER, ADD FK

Tom Lane wrote:
> Utterly wrong.  When you commit you will physically drop the old table.
> If there is a SELECT running against the old table it will be quite
> unhappy after that.

How can we drop the file at commit, given that a serializable 
transaction's snapshot should still be able to see old relfilenode's 
content?

(If the serializable transaction has already acquired a read lock before 
the TRUNCATE begins, it will block the TRUNCATE -- but there is no 
guarantee that the operations will be ordered like that.)

-Neil