Re: EXPLAIN: showing ReadStream / prefetch stats

On Tue, Apr 7, 2026 at 8:36 AM Tomas Vondra <tomas(at)vondra(dot)me> wrote:
>
> 3) Used (es_instrument & INSTRUMENT_IO) more consistently. A couple
> places in the executor still checked just es_instrument, and so would
> collect stats even if not needed. Be consistent.

I would argue for only allocating the shared instrumentation if they
will be displayed, but I don't feel that strongly about it.

I took another look at just 0002 just to double-check the read stream
counters. It seems fine.
Perhaps we should free the TableScanInstrumentation in heap_endscan().
It isn't that important of a leak, but the other things palloc'd in
heap_beginscan() are freed.

I also wondered if it is clear without a comment why we don't count a
wait when READ_BUFFERS_SYNCHRONOUSLY sets needed_wait (which we added
to make sure distance ramps up). I think it's fine; I'm just musing.

- Melanie