max_slot_wal_keep_size comment in postgresql.conf

At Tue, 26 May 2020 09:10:40 -0400, Jeff Janes <jeff.janes@gmail.com> wrote in

In postgresql.conf, it says:

#max_slot_wal_keep_size = -1 # measured in bytes; -1 disables

I don't know if that is describing the dimension of this parameter or the
units of it, but the default units for it are megabytes, not individual
bytes, so I think it is pretty confusing.

Agreed. It should be a leftover at the time the unit was changed
(before committed) to MB from bytes. The default value makes the
confusion worse.

Is the following works?

#max_slot_wal_keep_size = -1 # in MB; -1 disables

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center

On Tue, 26 May 2020 at 21:46, Kyotaro Horiguchi <horikyota.ntt@gmail.com>
wrote:

At Tue, 26 May 2020 09:10:40 -0400, Jeff Janes <jeff.janes@gmail.com>
wrote in

In postgresql.conf, it says:

#max_slot_wal_keep_size = -1 # measured in bytes; -1 disables

I don't know if that is describing the dimension of this parameter or the
units of it, but the default units for it are megabytes, not individual
bytes, so I think it is pretty confusing.

Agreed. It should be a leftover at the time the unit was changed
(before committed) to MB from bytes. The default value makes the
confusion worse.

Is the following works?

#max_slot_wal_keep_size = -1 # in MB; -1 disables

Extreme pedant question: Is it MB (10^6 bytes) or MiB (2^20 bytes)?

On Wed, May 27, 2020 at 10:46:27AM +0900, Kyotaro Horiguchi wrote:

Agreed. It should be a leftover at the time the unit was changed
(before committed) to MB from bytes. The default value makes the
confusion worse.

Is the following works?

#max_slot_wal_keep_size = -1 # in MB; -1 disables

Indeed, better to fix that. The few GUCs using memory units that have
such a mention in their comments use the actual name of the memory
unit, and not its abbreviation (see log_temp_files). So it seems more
logic to me to just use "in megabytes; -1 disables", that would be
also more consistent with the time-unit-based ones.
--
Michael

At Tue, 26 May 2020 22:56:39 -0400, Isaac Morland <isaac.morland@gmail.com> wrote in

On Tue, 26 May 2020 at 21:46, Kyotaro Horiguchi <horikyota.ntt@gmail.com>
wrote:

At Tue, 26 May 2020 09:10:40 -0400, Jeff Janes <jeff.janes@gmail.com>
wrote in

In postgresql.conf, it says:

#max_slot_wal_keep_size = -1 # measured in bytes; -1 disables

I don't know if that is describing the dimension of this parameter or the
units of it, but the default units for it are megabytes, not individual
bytes, so I think it is pretty confusing.

Agreed. It should be a leftover at the time the unit was changed
(before committed) to MB from bytes. The default value makes the
confusion worse.

Is the following works?

#max_slot_wal_keep_size = -1 # in MB; -1 disables

Extreme pedant question: Is it MB (10^6 bytes) or MiB (2^20 bytes)?

GUC variables for file/memory sizes are in a traditional
representation, that is, a power of two represented by
SI-prefixes. AFAICS PostgreSQL doesn't use binary-prefixed units.

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center

On 2020/05/27 15:11, Michael Paquier wrote:

On Wed, May 27, 2020 at 10:46:27AM +0900, Kyotaro Horiguchi wrote:

Agreed. It should be a leftover at the time the unit was changed
(before committed) to MB from bytes. The default value makes the
confusion worse.

Is the following works?

#max_slot_wal_keep_size = -1 # in MB; -1 disables

Indeed, better to fix that. The few GUCs using memory units that have
such a mention in their comments use the actual name of the memory
unit, and not its abbreviation (see log_temp_files). So it seems more
logic to me to just use "in megabytes; -1 disables", that would be
also more consistent with the time-unit-based ones.

+1

#temp_file_limit = -1 # limits per-process temp file space
# in kB, or -1 for no limit

BTW, the abbreviation "in kB" is used in temp_file_limit.

Regards,

--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION

At Wed, 27 May 2020 15:11:00 +0900, Michael Paquier <michael@paquier.xyz> wrote in

On Wed, May 27, 2020 at 10:46:27AM +0900, Kyotaro Horiguchi wrote:

Agreed. It should be a leftover at the time the unit was changed
(before committed) to MB from bytes. The default value makes the
confusion worse.

Is the following works?

#max_slot_wal_keep_size = -1 # in MB; -1 disables

Indeed, better to fix that. The few GUCs using memory units that have
such a mention in their comments use the actual name of the memory
unit, and not its abbreviation (see log_temp_files). So it seems more

I was not sure which is preferable. Does that mean we will fix the
following, too?

#temp_file_limit = -1 # limits per-process temp file space
# in kB, or -1 for no limit

logic to me to just use "in megabytes; -1 disables", that would be
also more consistent with the time-unit-based ones.

I don't oppose to full-spelling. How about the attached?

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center

On Wed, May 27, 2020 at 04:21:59PM +0900, Kyotaro Horiguchi wrote:

I don't oppose to full-spelling. How about the attached?

No problem from me.
--
Michael

On Wed, May 27, 2020 at 04:35:51PM +0900, Michael Paquier wrote:

On Wed, May 27, 2020 at 04:21:59PM +0900, Kyotaro Horiguchi wrote:

I don't oppose to full-spelling. How about the attached?

No problem from me.

And applied this one as of 55ca50d.
--
Michael

At Thu, 28 May 2020 15:44:26 +0900, Michael Paquier <michael@paquier.xyz> wrote in

On Wed, May 27, 2020 at 04:35:51PM +0900, Michael Paquier wrote:

On Wed, May 27, 2020 at 04:21:59PM +0900, Kyotaro Horiguchi wrote:

I don't oppose to full-spelling. How about the attached?

No problem from me.

And applied this one as of 55ca50d.

Thanks!

--
Kyotaro Horiguchi
NTT Open Source Software Center