On Fri, Jun 12, 2015 at 4:37 PM, Michael Nolan <htfoot(at)gmail(dot)com> wrote:
> The only thing I can come up that's happened since last night was that we
> ran the nightly vacuum analyze on that database, but I did not change the
> statistics target.
>
The answer to your question is no, parameters changes are worse would take
effect after a reboot - though most are used on the very next query that
runs.
The vacuum would indeed likely account for the gains - there being
significantly fewer dead/invisible rows to have to scan over and discard
while retrieving the live rows that fulfill your query.
David J.