As long as I'm about to change the xlog page headers, I have another
little idea. Wouldn't it be a good idea to allow three backup pages
per xlog record, not only two? It seems like three pages would be
a natural requirement for logging operations like index page splits.
We could support as many as four pages per record, but that would mean
having no free global bits in the info byte, which might be a bad idea.
I think three page bits and one free bit is a good compromise.
Thoughts?
regards, tom lane
