Re: [HACKERS] proposals for LLL, part 1

> Bruce Momjian wrote:
> >
> > You are correct.  We need to lock Proc stuctures during our scan, but we
> > don't need to keep the list in shared memory.  No reason to do it.  Do
> > we have to keep the Proc's locked while we get our table data locks.  I
>                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> No! Only while we are scanning Procs...
>
> > sure hope not.  Not sure how we are going prevent someone from
> > committing their transaction between our Proc scan and when we start our
> > transaction.  Not even sure if I should be worried about that.
>
> We shouldn't... It doesn't matter.

One more item.  If we don't lock Proc between the scan and our
aquisition of a transaction id, it is possible some other backend will
get a transaction id between the time we scan the Proc structure and
when we get our transaction id, causing us to look at rows that are part
of a non-committed transaction.  I think we have to get our transaction
id first, before scanning Proc.

There is definately an area of vulnerabilty there.  I am now wondering
how much we need to lock Proc during the scan.

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