On Tue, Dec 17, 2019 at 8:08 AM Laurenz Albe <laurenz.albe@xxxxxxxxxxx> wrote:
On Mon, 2019-12-16 at 15:50 -0500, Tom Lane wrote:
> Peter Geoghegan <pg@xxxxxxx> writes:
> > Why do the first and the twentieth executions of the query have almost
> > identical "buffers shared/read" numbers? That seems odd.
>
> It's repeat execution of the same query, so that doesn't seem odd to me.
Really? Shouldn't the blocks be in shared buffers after a couple
of executions?
If it is doing a seq scan (I don't know if it is) they intentionally use a small ring buffer to, so they evict their own recently used blocks, rather than evicting other people's blocks. So these blocks won't build up in shared_buffers very rapidly just on the basis of repeated seq scans.
Cheers,
Jeff
