Re: Avoiding repeated snapshot computation

Andres Freund <andres@anarazel.de> writes:
> You could also try if it makes a difference reducing SnapshotData to one 
> instead of two cachelines. The data itself fits into one without problems.
> Trivial patch attached.

On what grounds do you argue that this patch gets SnapshotData into one
cacheline today (and on what hardware), or that it will continue to do
so in the future?  If we're this close to the edge then any future
addition to the struct will destroy the point.  I'd just as soon keep
the fields in a logical order.
        regards, tom lane