Re: [HACKERS] [PATCH] Vacuum: Update FSM more frequently

On Fri, Feb 9, 2018 at 12:45 AM, Claudio Freire <klaussfreire@gmail.com> wrote:
> On Thu, Feb 8, 2018 at 1:36 AM, Masahiko Sawada <sawada.mshk@gmail.com> wrote:
>> On Tue, Feb 6, 2018 at 9:51 PM, Claudio Freire <klaussfreire@gmail.com> wrote:
>>> I can look into doing 3, that *might* get rid of the need to do that
>>> initial FSM vacuum, but all other intermediate vacuums are still
>>> needed.
>>
>> Understood. So how about that this patch focuses only make FSM vacuum
>> more frequently and leaves the initial FSM vacuum and the handling
>> cancellation cases? The rest can be a separate patch.
>
> Ok.
>
> Attached split patches. All but the initial FSM pass is in 1, the
> initial FSM pass as in the original patch is in 2.
>
> I will post an alternative patch for 2 when/if I have one. In the
> meanwhile, we can talk about 1.

Thank you for updating the patch!

+            /* Tree pruning for partial vacuums */
+            if (threshold)
+            {
+                child_avail = fsm_get_avail(page, slot);
+                if (child_avail >= threshold)
+                    continue;
+            }

I think slots in a non-leaf page might not have a correct value
because fsm_set_avail doesn't propagate up beyond pages. So do we need
to check the root of child page rather than a slot in the non-lead
page? I might be missing something though.

Regards,

--
Masahiko Sawada
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center