Обсуждение: Understanding “max_wal_size” and “min_wal_size” parameters default values from postgresql.conf file
According to documentation, for "min_wal_size" and "max_wal_size" parameters
default values are:
For max_wal_size
: The default is 1 GB
For min_wal_size
: The default is 80 MB
Then I look this parameters from my database config:
select name, setting, unit
from pg_settings
where name in ('min_wal_size', 'max_wal_size')
Gives result:
name | setting | unit
----------------------------------
max_wal_size | 64 |
min_wal_size | 5 |
I have 2 questions:
1) Why these values doesn't match default values, which are shown in docs? I never changed config settings at all.
2) Why unit
column is empty/NULL for these parameters? What means 64 and 5 values in this case? MB
? GB
? or what?
Why this is not like for example work_mem
parameter, when everything is clear:
name | setting | unit
----------------------------------
work_mem | 4096 | kB
otar shavadze <oshavadze@gmail.com> writes: > name | setting | unit---------------------------------- > max_wal_size | 64 | > min_wal_size | 5 | > I have 2 questions: > 1) Why these values doesn't match default values, which are shown in docs? > I never changed config settings at all. They do match the defaults. > 2) Why unit column is empty/NULL for these parameters? What means 64 and 5 > values in this case? MB? GB? or what? The problem seems to be that somebody missed out adding GUC_UNIT_XSEGS to the switch in GetConfigOptionByNum. It should be showing you something like "16MB" in the unit column, I think. regards, tom lane
Thank you very much
On Mon, Oct 3, 2016 at 11:46 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
otar shavadze <oshavadze@gmail.com> writes:
> name | setting | unit----------------------------------
> max_wal_size | 64 |
> min_wal_size | 5 |
> I have 2 questions:
> 1) Why these values doesn't match default values, which are shown in docs?
> I never changed config settings at all.
They do match the defaults.
> 2) Why unit column is empty/NULL for these parameters? What means 64 and 5
> values in this case? MB? GB? or what?
The problem seems to be that somebody missed out adding GUC_UNIT_XSEGS
to the switch in GetConfigOptionByNum. It should be showing you
something like "16MB" in the unit column, I think.
regards, tom lane