On 2020/11/16 18:24, Masahiro Ikeda wrote:
On 2020-11-13 12:32, lchch1...@sina.cn wrote:
Now, pg_stat_wal supports reset all informantion in WalStats
using pg_stat_reset_shared('wal') function.
Isn't it enough?
Yes it ok, sorry I miss this infomation.
OK.
3. I do not think it's a correct describe in document for
'wal_buffers_full'.
Where should I rewrite the description? If my understanding is not
correct, please let me know.
Sorry I have not described it clearly, because I can not understand
the meaning of this
column after I read the describe in document.
And now I read the source code of walwrite and found the place where
'wal_buffers_full'
added is for a backend to wait a wal buffer which is occupied by other
wal page, so the
backend flush the old page in the wal buffer(after wait it can).
So i think the origin decribe in document is not so in point, we can
describe it such as
'Total number of times WAL data written to the disk because a backend
yelled a wal buffer
for an advanced wal page.
Sorry if my understand is wrong.
Thanks for your comments.
You're understanding is almost the same as mine.
It describes when not only backends but also other backgrounds initialize a new
wal page,
wal buffer's space is already used and there is no space.
'Total number of times WAL data written to the disk because a backend
yelled a wal buffer for an advanced wal page'
Thanks for your suggestion.
I wondered that users may confuse about how to use "wal_buffers_full" and how
to tune parameters.
I thought the reason which wal buffer has no space is
important for users to tune the wal_buffers parameter.
How about the following comments?
'Total number of times WAL data was written to the disk because WAL buffers got
full
when to initialize a new WAL page'
Or what about the following?
Total number of times WAL data was written to the disk, to claim the buffer
page to insert new WAL data when the WAL buffers got filled up with unwritten
WAL data.
Regards,
--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION
