Heikki Linnakangas <hlinnakangas@vmware.com> writes:
> On 07.06.2013 19:33, Tom Lane wrote:
>> Not only is that a horrible layering/modularity violation, but surely
>> LockBuffer can have no idea how much WAL space will be needed.
> It can be just a conservative guess, like, 32KB. That should be enough
> for almost all WAL-logged operations. The only exception that comes to
> mind is a commit record, which can be arbitrarily large, when you have a
> lot of subtransactions or dropped/created relations.
What happens when several updates are occurring concurrently?
regards, tom lane