Tom Lane wrote:
This is actually a bit nasty. Your proposed patch doesn't really work,
because of the concern that is now commented at the head of
transformAlterTableStmt:
* CAUTION: resist the temptation to do any work here that depends on the
* current state of the table. Actual execution of the command might not
* occur till some future transaction. Hence, we do only purely syntactic
* transformations here, comparable to the processing of CREATE TABLE.
IOW, we don't actually *know* at parse analysis time which table will be
affected.
I don't understand that. Why would the execution be delayed to a future
transaction? You can't PREPARE an ALTER TABLE, right?
According to the comments in transformInhRelation, it has the same
problem...
Maybe we should give up doing any CREATE/ALTER processing at all at
parse analysis time, and push it all to execution time. I got rid of
parse-time processing of other utility statements during the plan
caching work a couple months ago, because of concerns very much like
this, but I hadn't bit the bullet for CREATE/ALTER TABLE because it was
such a huge chunk of code. But maybe we'd better do it.
We'll still need something smaller to back patch, I think. :(
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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