Re: Using read stream in autoprewarm

On Wednesday, November 27th, 2024 at 11:19 AM, Nazir Bilal Yavuz
<byavuz81(at)gmail(dot)com> wrote:
> > v2-0001-Use-read-stream-in-autoprewarm.patch
> > + bool *rs_have_free_buffer = per_buffer_data;
> > +
> > +
> > + *rs_have_free_buffer = true;
> > +
> >
> > Not sure if I understand why this variable is needed, it seems that
it is only
> > written and never read? Just as comparison, the
block_range_read_stream_cb
> > callback used on pg_prewarm seems to not use the per_buffer_data
parameter.
>
>
> Actually, it is read in the main loop of the
> autoprewarm_database_main() function:
>
> /* There are no free buffers left in shared buffers, break the loop. */
> else if (!(*rs_have_free_buffer))
> break;
>
> apw_read_stream_next_block() callback function sets
> rs_have_free_buffer's value to false when there is no free buffer left
> in the shared buffers. And the code above terminates the main loop in
> the autoprewarm_database_main() function when it is set to false.
>
> block_range_read_stream_cb() callback is used when the callback only
> needs to loop over the block numbers. However, for the autoprewarm
> case; the callback function needs to do additional checks so another
> callback and the use of this variable are required.

Ohh, I see, thanks very much for the explanation.

> v3 is attached.

Thanks.

I don't know if there is another way that this patch could be tested?
Looking
forward on other reviews on this.

--
Matheus Alcantara
EDB: https://www.enterprisedb.com