Re: EXPLAIN BUFFERS: dirtied

I've read this article: https://wiki.postgresql.org/wiki/Hint_Bits

It says:

> A plain SELECT, count(*), or VACUUM on the entire table will check 
> every tuple for visibility and set its hint bits. 

Suppose, a new page was created using many INSERTs, and then was written 
to disk during a checkpoint. There were no SELECTs or VACUUM on the page 
or table yet. Will the following SELECT of one tuple from the page 
update hint bits for ALL tuples on the page? Is that correct?

When a page is initially created and then is being written to disk 
during a checkpoint, does checkpoint writer update the hint bits before 
writing the page, or the following SELECT/VACUUM will have to do that 
(possibly loading/updating/writing the page again)?

Regards,
Vitaliy

On 2018-01-29 20:38, Tom Lane wrote:
> Vitaliy Garnashevich <vgarnashevich@gmail.com> writes:
>> But what is "dirtied" statistics? When a SELECT query could make pages
>> dirty?
> Setting hint bits on recently-committed rows.
>
>             regards, tom lane
>