Bruce Momjian <pgman@xxxxxxxxxxxxxxxx> writes: > Ed L. wrote: >> We have ~75 pgsql clusters running in environments where downtime >> comes at a premium cost. We often run multiple clusters on a >> single box, and find it necessary to adjust the size of the >> static DB cache as we add or move clusters. Unfortunately, that >> means some downtime. It would be extremely useful in minimizing >> downtime to be able to dynamically resize the DB cache without >> having to restart the cluster. How hard would that be? > We can't think of how to do because it is all shared memory shared by > ever forked process --- does that help explain its complexity? There isn't any particularly good reason to be resizing shared_buffers on the fly anyway; much easier to let the kernel adapt the size of its disk cache instead. Best practice for shared_buffers is to set it somewhere in the range of 10K to 50K and forget it. If Ed was thinking of something other than shared_buffers, he should explain what. regards, tom lane
