Re: New statistics for tuning WAL buffer size

2020-10-16 Thread Masahiro Ikeda
On 2020-10-15 19:49, Fujii Masao wrote: On 2020/10/13 11:57, Masahiro Ikeda wrote: On 2020-10-06 15:57, Masahiro Ikeda wrote: 2.  Number of when new WAL file is created and zero-filled. As Fujii-san already commented, I think it's good for tuning. Just idea; it may be worth exposing the numbe

Re: New statistics for tuning WAL buffer size

2020-10-15 Thread Fujii Masao
On 2020/10/13 11:57, Masahiro Ikeda wrote: On 2020-10-06 15:57, Masahiro Ikeda wrote: Hi, I think it's better to add other WAL statistics to the pg_stat_wal view. I'm thinking to add the following statistics. Please let me know your thoughts. 1.  Basic wal statistics * wal_records: Total n

Re: New statistics for tuning WAL buffer size

2020-10-12 Thread Masahiro Ikeda
On 2020-10-06 15:57, Masahiro Ikeda wrote: Hi, I think it's better to add other WAL statistics to the pg_stat_wal view. I'm thinking to add the following statistics. Please let me know your thoughts. 1. Basic wal statistics * wal_records: Total number of WAL records generated * wal_fpi: To

Re: New statistics for tuning WAL buffer size

2020-10-05 Thread Masahiro Ikeda
Hi, I think it's better to add other WAL statistics to the pg_stat_wal view. I'm thinking to add the following statistics. Please let me know your thoughts. 1. Basic wal statistics * wal_records: Total number of WAL records generated * wal_fpi: Total number of WAL full page images generated

Re: New statistics for tuning WAL buffer size

2020-10-01 Thread Masahiro Ikeda
On 2020-10-02 10:21, Fujii Masao wrote: On 2020/10/01 13:35, Fujii Masao wrote: On 2020/10/01 12:56, Masahiro Ikeda wrote: On 2020-10-01 11:33, Amit Kapila wrote: On Thu, Oct 1, 2020 at 6:53 AM Kyotaro Horiguchi wrote: At Thu, 1 Oct 2020 09:05:19 +0900, Fujii Masao wrote in > > > On 20

Re: New statistics for tuning WAL buffer size

2020-10-01 Thread Fujii Masao
On 2020/10/01 13:35, Fujii Masao wrote: On 2020/10/01 12:56, Masahiro Ikeda wrote: On 2020-10-01 11:33, Amit Kapila wrote: On Thu, Oct 1, 2020 at 6:53 AM Kyotaro Horiguchi wrote: At Thu, 1 Oct 2020 09:05:19 +0900, Fujii Masao wrote in > > > On 2020/09/30 20:21, Amit Kapila wrote: > >

RE: New statistics for tuning WAL buffer size

2020-10-01 Thread tsunakawa.ta...@fujitsu.com
From: Fujii Masao > I think that we can improve that, for example, by storing backend id > into WalSndCtl and making pg_stat_get_wal_senders() directly > get the walsender's LocalPgBackendStatus with the backend id, > rather than joining pg_stat_get_activity() and pg_stat_get_wal_senders(). Yeah,

Re: New statistics for tuning WAL buffer size

2020-10-01 Thread Fujii Masao
On 2020/10/01 10:50, tsunakawa.ta...@fujitsu.com wrote: From: Kyotaro Horiguchi Another reason that I mildly want to object to subdivided functions is I was annoyed that a stats view makes many individual calls to functions that internally share the same statistics entry. That behavior requ

Re: New statistics for tuning WAL buffer size

2020-09-30 Thread Fujii Masao
On 2020/10/01 12:56, Masahiro Ikeda wrote: On 2020-10-01 11:33, Amit Kapila wrote: On Thu, Oct 1, 2020 at 6:53 AM Kyotaro Horiguchi wrote: At Thu, 1 Oct 2020 09:05:19 +0900, Fujii Masao wrote in > > > On 2020/09/30 20:21, Amit Kapila wrote: > > On Tue, Sep 29, 2020 at 9:23 PM Fujii Masao

Re: New statistics for tuning WAL buffer size

2020-09-30 Thread Masahiro Ikeda
On 2020-10-01 11:33, Amit Kapila wrote: On Thu, Oct 1, 2020 at 6:53 AM Kyotaro Horiguchi wrote: At Thu, 1 Oct 2020 09:05:19 +0900, Fujii Masao wrote in > > > On 2020/09/30 20:21, Amit Kapila wrote: > > On Tue, Sep 29, 2020 at 9:23 PM Fujii Masao > > wrote: > >> > >> On 2020/09/29 11:51, Ma

Re: New statistics for tuning WAL buffer size

2020-09-30 Thread Amit Kapila
On Thu, Oct 1, 2020 at 6:53 AM Kyotaro Horiguchi wrote: > > At Thu, 1 Oct 2020 09:05:19 +0900, Fujii Masao > wrote in > > > > > > On 2020/09/30 20:21, Amit Kapila wrote: > > > On Tue, Sep 29, 2020 at 9:23 PM Fujii Masao > > > wrote: > > >> > > >> On 2020/09/29 11:51, Masahiro Ikeda wrote: > > >

RE: New statistics for tuning WAL buffer size

2020-09-30 Thread tsunakawa.ta...@fujitsu.com
From: Kyotaro Horiguchi > Another reason that I mildly want to object to subdivided functions is > I was annoyed that a stats view makes many individual calls to > functions that internally share the same statistics entry. That > behavior required me to provide an entry-caching feature to my > sh

Re: New statistics for tuning WAL buffer size

2020-09-30 Thread Kyotaro Horiguchi
At Thu, 1 Oct 2020 09:05:19 +0900, Fujii Masao wrote in > > > On 2020/09/30 20:21, Amit Kapila wrote: > > On Tue, Sep 29, 2020 at 9:23 PM Fujii Masao > > wrote: > >> > >> On 2020/09/29 11:51, Masahiro Ikeda wrote: > >>> On 2020-09-29 11:43, Amit Kapila wrote: > On Tue, Sep 29, 2020 at 7:

Re: New statistics for tuning WAL buffer size

2020-09-30 Thread Fujii Masao
On 2020/09/30 20:21, Amit Kapila wrote: On Tue, Sep 29, 2020 at 9:23 PM Fujii Masao wrote: On 2020/09/29 11:51, Masahiro Ikeda wrote: On 2020-09-29 11:43, Amit Kapila wrote: On Tue, Sep 29, 2020 at 7:39 AM Masahiro Ikeda wrote: On 2020-09-28 12:43, Amit Kapila wrote: On Mon, Sep 28, 2

Re: New statistics for tuning WAL buffer size

2020-09-30 Thread Amit Kapila
On Tue, Sep 29, 2020 at 9:23 PM Fujii Masao wrote: > > On 2020/09/29 11:51, Masahiro Ikeda wrote: > > On 2020-09-29 11:43, Amit Kapila wrote: > >> On Tue, Sep 29, 2020 at 7:39 AM Masahiro Ikeda > >> wrote: > >>> > >>> On 2020-09-28 12:43, Amit Kapila wrote: > >>> > On Mon, Sep 28, 2020 at 8:24 A

Re: New statistics for tuning WAL buffer size

2020-09-29 Thread Fujii Masao
On 2020/09/29 11:51, Masahiro Ikeda wrote: On 2020-09-29 11:43, Amit Kapila wrote: On Tue, Sep 29, 2020 at 7:39 AM Masahiro Ikeda wrote: On 2020-09-28 12:43, Amit Kapila wrote: > On Mon, Sep 28, 2020 at 8:24 AM Kyotaro Horiguchi > wrote: >> >> At Mon, 28 Sep 2020 08:11:23 +0530, Amit Kapi

Re: New statistics for tuning WAL buffer size

2020-09-28 Thread Masahiro Ikeda
On 2020-09-29 11:43, Amit Kapila wrote: On Tue, Sep 29, 2020 at 7:39 AM Masahiro Ikeda wrote: On 2020-09-28 12:43, Amit Kapila wrote: > On Mon, Sep 28, 2020 at 8:24 AM Kyotaro Horiguchi > wrote: >> >> At Mon, 28 Sep 2020 08:11:23 +0530, Amit Kapila >> wrote in >> > One other thing that occur

Re: New statistics for tuning WAL buffer size

2020-09-28 Thread Amit Kapila
On Tue, Sep 29, 2020 at 7:39 AM Masahiro Ikeda wrote: > > On 2020-09-28 12:43, Amit Kapila wrote: > > On Mon, Sep 28, 2020 at 8:24 AM Kyotaro Horiguchi > > wrote: > >> > >> At Mon, 28 Sep 2020 08:11:23 +0530, Amit Kapila > >> wrote in > >> > One other thing that occurred to me today is can't we

Re: New statistics for tuning WAL buffer size

2020-09-28 Thread Masahiro Ikeda
On 2020-09-28 12:43, Amit Kapila wrote: On Mon, Sep 28, 2020 at 8:24 AM Kyotaro Horiguchi wrote: At Mon, 28 Sep 2020 08:11:23 +0530, Amit Kapila wrote in > One other thing that occurred to me today is can't we keep this as > part of PgStat_GlobalStats? We can use pg_stat_reset_shared('wal')

Re: New statistics for tuning WAL buffer size

2020-09-27 Thread Amit Kapila
On Mon, Sep 28, 2020 at 8:24 AM Kyotaro Horiguchi wrote: > > At Mon, 28 Sep 2020 08:11:23 +0530, Amit Kapila > wrote in > > One other thing that occurred to me today is can't we keep this as > > part of PgStat_GlobalStats? We can use pg_stat_reset_shared('wal'); to > > reset it. It seems to me t

Re: New statistics for tuning WAL buffer size

2020-09-27 Thread Kyotaro Horiguchi
At Mon, 28 Sep 2020 08:11:23 +0530, Amit Kapila wrote in > One other thing that occurred to me today is can't we keep this as > part of PgStat_GlobalStats? We can use pg_stat_reset_shared('wal'); to > reset it. It seems to me this is a cluster-wide stats and somewhat > similar to some of the oth

Re: New statistics for tuning WAL buffer size

2020-09-27 Thread Amit Kapila
On Mon, Sep 28, 2020 at 7:00 AM Masahiro Ikeda wrote: > > On 2020-09-26 19:18, Amit Kapila wrote > > > This makes sense to me. I think even if such background processes have > > to write WAL due to wal_buffers, it will be accounted next time the > > backend sends the stats. > > Thanks for your com

Re: New statistics for tuning WAL buffer size

2020-09-27 Thread Masahiro Ikeda
On 2020-09-26 19:18, Amit Kapila wrote: On Fri, Sep 25, 2020 at 11:06 PM Fujii Masao wrote: On 2020/09/25 12:06, Masahiro Ikeda wrote: > On 2020-09-18 11:11, Kyotaro Horiguchi wrote: >> At Fri, 18 Sep 2020 09:40:11 +0900, Masahiro Ikeda >> wrote in >>> Thanks. I confirmed that it causes HOT p

Re: New statistics for tuning WAL buffer size

2020-09-27 Thread Kyotaro Horiguchi
At Sat, 26 Sep 2020 15:48:49 +0530, Amit Kapila wrote in > On Fri, Sep 25, 2020 at 11:06 PM Fujii Masao > wrote: > > > > On 2020/09/25 12:06, Masahiro Ikeda wrote: > > > On 2020-09-18 11:11, Kyotaro Horiguchi wrote: > > >> At Fri, 18 Sep 2020 09:40:11 +0900, Masahiro Ikeda > > >> wrote in > >

Re: New statistics for tuning WAL buffer size

2020-09-26 Thread Amit Kapila
On Fri, Sep 25, 2020 at 11:06 PM Fujii Masao wrote: > > On 2020/09/25 12:06, Masahiro Ikeda wrote: > > On 2020-09-18 11:11, Kyotaro Horiguchi wrote: > >> At Fri, 18 Sep 2020 09:40:11 +0900, Masahiro Ikeda > >> wrote in > >>> Thanks. I confirmed that it causes HOT pruning or killing of > >>> dead

Re: New statistics for tuning WAL buffer size

2020-09-25 Thread Fujii Masao
On 2020/09/25 12:06, Masahiro Ikeda wrote: On 2020-09-18 11:11, Kyotaro Horiguchi wrote: At Fri, 18 Sep 2020 09:40:11 +0900, Masahiro Ikeda wrote in Thanks. I confirmed that it causes HOT pruning or killing of dead index tuple if DecodeCommit() is called. As you said, DecodeCommit() may ac

Re: New statistics for tuning WAL buffer size

2020-09-24 Thread Masahiro Ikeda
On 2020-09-18 11:11, Kyotaro Horiguchi wrote: At Fri, 18 Sep 2020 09:40:11 +0900, Masahiro Ikeda wrote in Thanks. I confirmed that it causes HOT pruning or killing of dead index tuple if DecodeCommit() is called. As you said, DecodeCommit() may access the system table. ... The wals are gener

Re: New statistics for tuning WAL buffer size

2020-09-17 Thread Kyotaro Horiguchi
At Fri, 18 Sep 2020 09:40:11 +0900, Masahiro Ikeda wrote in > Thanks. I confirmed that it causes HOT pruning or killing of > dead index tuple if DecodeCommit() is called. > > As you said, DecodeCommit() may access the system table. ... > The wals are generated only when logical replication is p

Re: New statistics for tuning WAL buffer size

2020-09-17 Thread Masahiro Ikeda
On 2020-09-15 17:10, Fujii Masao wrote: On 2020/09/15 15:52, Masahiro Ikeda wrote: On 2020-09-11 01:40, Fujii Masao wrote: On 2020/09/09 13:57, Masahiro Ikeda wrote: On 2020-09-07 16:19, Fujii Masao wrote: On 2020/09/07 9:58, Masahiro Ikeda wrote: Thanks for the review and advice! On 2020-0

Re: New statistics for tuning WAL buffer size

2020-09-15 Thread Fujii Masao
On 2020/09/15 15:52, Masahiro Ikeda wrote: On 2020-09-11 01:40, Fujii Masao wrote: On 2020/09/09 13:57, Masahiro Ikeda wrote: On 2020-09-07 16:19, Fujii Masao wrote: On 2020/09/07 9:58, Masahiro Ikeda wrote: Thanks for the review and advice! On 2020-09-03 16:05, Fujii Masao wrote: On 202

Re: New statistics for tuning WAL buffer size

2020-09-14 Thread Masahiro Ikeda
On 2020-09-11 01:40, Fujii Masao wrote: On 2020/09/09 13:57, Masahiro Ikeda wrote: On 2020-09-07 16:19, Fujii Masao wrote: On 2020/09/07 9:58, Masahiro Ikeda wrote: Thanks for the review and advice! On 2020-09-03 16:05, Fujii Masao wrote: On 2020/09/02 18:56, Masahiro Ikeda wrote: +/* -

Re: New statistics for tuning WAL buffer size

2020-09-11 Thread Fujii Masao
On 2020/09/11 16:54, Kyotaro Horiguchi wrote: At Fri, 11 Sep 2020 13:48:49 +0900, Fujii Masao wrote in On 2020/09/11 12:17, Kyotaro Horiguchi wrote: Hello. At Wed, 09 Sep 2020 13:57:37 +0900, Masahiro Ikeda wrote in I checked what function calls XLogBackgroundFlush() which calls Advanc

Re: New statistics for tuning WAL buffer size

2020-09-11 Thread Kyotaro Horiguchi
At Fri, 11 Sep 2020 13:48:49 +0900, Fujii Masao wrote in > > > On 2020/09/11 12:17, Kyotaro Horiguchi wrote: > > Hello. > > At Wed, 09 Sep 2020 13:57:37 +0900, Masahiro Ikeda > > wrote in > >> I checked what function calls XLogBackgroundFlush() which calls > >> AdvanceXLInsertBuffer() to incr

Re: New statistics for tuning WAL buffer size

2020-09-10 Thread Fujii Masao
On 2020/09/11 12:17, Kyotaro Horiguchi wrote: Hello. At Wed, 09 Sep 2020 13:57:37 +0900, Masahiro Ikeda wrote in I checked what function calls XLogBackgroundFlush() which calls AdvanceXLInsertBuffer() to increment m_wal_buffers_full. I found that WalSndWaitForWal() calls it, so I added it

Re: New statistics for tuning WAL buffer size

2020-09-10 Thread Kyotaro Horiguchi
Hello. At Wed, 09 Sep 2020 13:57:37 +0900, Masahiro Ikeda wrote in > I checked what function calls XLogBackgroundFlush() which calls > AdvanceXLInsertBuffer() to increment m_wal_buffers_full. > > I found that WalSndWaitForWal() calls it, so I added it. > Is it better to move it in WalSndLoop()

Re: New statistics for tuning WAL buffer size

2020-09-10 Thread Fujii Masao
On 2020/09/09 13:57, Masahiro Ikeda wrote: On 2020-09-07 16:19, Fujii Masao wrote: On 2020/09/07 9:58, Masahiro Ikeda wrote: Thanks for the review and advice! On 2020-09-03 16:05, Fujii Masao wrote: On 2020/09/02 18:56, Masahiro Ikeda wrote: +/* -- + * Backend types + * --

Re: New statistics for tuning WAL buffer size

2020-09-08 Thread Masahiro Ikeda
On 2020-09-07 16:19, Fujii Masao wrote: On 2020/09/07 9:58, Masahiro Ikeda wrote: Thanks for the review and advice! On 2020-09-03 16:05, Fujii Masao wrote: On 2020/09/02 18:56, Masahiro Ikeda wrote: +/* -- + * Backend types + * -- You seem to forget to add "*/" into the above

Re: New statistics for tuning WAL buffer size

2020-09-07 Thread Fujii Masao
On 2020/09/07 9:58, Masahiro Ikeda wrote: Thanks for the review and advice! On 2020-09-03 16:05, Fujii Masao wrote: On 2020/09/02 18:56, Masahiro Ikeda wrote: +/* -- + * Backend types + * -- You seem to forget to add "*/" into the above comment. This issue could cause the f

Re: New statistics for tuning WAL buffer size

2020-09-06 Thread Masahiro Ikeda
Thanks for the review and advice! On 2020-09-03 16:05, Fujii Masao wrote: On 2020/09/02 18:56, Masahiro Ikeda wrote: +/* -- + * Backend types + * -- You seem to forget to add "*/" into the above comment. This issue could cause the following compiler warning. ../../src/include/p

Re: New statistics for tuning WAL buffer size

2020-09-05 Thread Magnus Hagander
On Fri, Sep 4, 2020 at 5:42 AM Fujii Masao wrote: > > > On 2020/09/04 11:50, tsunakawa.ta...@fujitsu.com wrote: > > From: Fujii Masao > >>> I changed the view name from pg_stat_walwrites to pg_stat_walwriter. > >>> I think it is better to match naming scheme with other views like > >> pg_stat_bg

Re: New statistics for tuning WAL buffer size

2020-09-03 Thread Fujii Masao
On 2020/09/04 11:50, tsunakawa.ta...@fujitsu.com wrote: From: Fujii Masao I changed the view name from pg_stat_walwrites to pg_stat_walwriter. I think it is better to match naming scheme with other views like pg_stat_bgwriter, which is for bgwriter statistics but it has the statistics rela

RE: New statistics for tuning WAL buffer size

2020-09-03 Thread tsunakawa.ta...@fujitsu.com
From: Fujii Masao > > I changed the view name from pg_stat_walwrites to pg_stat_walwriter. > > I think it is better to match naming scheme with other views like > pg_stat_bgwriter, > > which is for bgwriter statistics but it has the statistics related to > > backend. > > I prefer the view name p

Re: New statistics for tuning WAL buffer size

2020-09-03 Thread Fujii Masao
On 2020/09/02 18:56, Masahiro Ikeda wrote: +/* -- + * Backend types + * -- You seem to forget to add "*/" into the above comment. This issue could cause the following compiler warning. ../../src/include/pgstat.h:761:1: warning: '/*' within block comment [-Wcomment] Thanks fo

Re: New statistics for tuning WAL buffer size

2020-09-02 Thread Masahiro Ikeda
+/* -- + * Backend types + * -- You seem to forget to add "*/" into the above comment. This issue could cause the following compiler warning. ../../src/include/pgstat.h:761:1: warning: '/*' within block comment [-Wcomment] Thanks for the comment. I fixed. The contents of pg_s

Re: New statistics for tuning WAL buffer size

2020-09-01 Thread Fujii Masao
On 2020/08/24 21:00, Masahiro Ikeda wrote: On 2020-08-24 20:45, Masahiro Ikeda wrote: Hi, thanks for useful comments. I agree to expose the number of WAL write caused by full of WAL buffers. It's helpful when tuning wal_buffers size. Haribabu separated that number into two fields in his pat

Re: New statistics for tuning WAL buffer size

2020-08-24 Thread Masahiro Ikeda
On 2020-08-24 20:45, Masahiro Ikeda wrote: Hi, thanks for useful comments. I agree to expose the number of WAL write caused by full of WAL buffers. It's helpful when tuning wal_buffers size. Haribabu separated that number into two fields in his patch; one is the number of WAL write by backend

Re: New statistics for tuning WAL buffer size

2020-08-24 Thread Masahiro Ikeda
Hi, thanks for useful comments. I agree to expose the number of WAL write caused by full of WAL buffers. It's helpful when tuning wal_buffers size. Haribabu separated that number into two fields in his patch; one is the number of WAL write by backend, and another is by background processes an

Re: New statistics for tuning WAL buffer size

2020-08-20 Thread Fujii Masao
On 2020/08/21 12:08, tsunakawa.ta...@fujitsu.com wrote: From: Fujii Masao Just idea; it may be worth exposing the number of when new WAL file is created and zero-filled. This initialization may have impact on the performance of write-heavy workload generating lots of WAL. If this number is r

RE: New statistics for tuning WAL buffer size

2020-08-20 Thread tsunakawa.ta...@fujitsu.com
From: Fujii Masao > Just idea; it may be worth exposing the number of when new WAL file is > created and zero-filled. This initialization may have impact on > the performance of write-heavy workload generating lots of WAL. If this > number is reported high, to reduce the number of this initializat

RE: New statistics for tuning WAL buffer size

2020-08-20 Thread tsunakawa.ta...@fujitsu.com
From: Fujii Masao > I agree to expose the number of WAL write caused by full of WAL buffers. > It's helpful when tuning wal_buffers size. Haribabu separated that number > into two fields in his patch; one is the number of WAL write by backend, > and another is by background processes and workers.

Re: New statistics for tuning WAL buffer size

2020-08-20 Thread Fujii Masao
On 2020/08/20 20:01, Fujii Masao wrote: On 2020/08/19 14:10, Masahiro Ikeda wrote: On 2020-08-19 13:49, tsunakawa.ta...@fujitsu.com wrote: From: Masahiro Ikeda If my understanding is correct, we have to measure the performance impact first. Do you know HariBabu is now trying to solve it?

Re: New statistics for tuning WAL buffer size

2020-08-20 Thread Fujii Masao
On 2020/08/19 14:10, Masahiro Ikeda wrote: On 2020-08-19 13:49, tsunakawa.ta...@fujitsu.com wrote: From: Masahiro Ikeda If my understanding is correct, we have to measure the performance impact first. Do you know HariBabu is now trying to solve it? If not, I will try to modify patches to ap

RE: New statistics for tuning WAL buffer size

2020-08-18 Thread Masahiro Ikeda
On 2020-08-19 13:49, tsunakawa.ta...@fujitsu.com wrote: From: Masahiro Ikeda If my understanding is correct, we have to measure the performance impact first. Do you know HariBabu is now trying to solve it? If not, I will try to modify patches to apply HEAD. No, he's not doing it anymore. It'

RE: New statistics for tuning WAL buffer size

2020-08-18 Thread tsunakawa.ta...@fujitsu.com
From: Masahiro Ikeda > If my understanding is correct, we have to measure the performance > impact first. > Do you know HariBabu is now trying to solve it? If not, I will try to > modify patches to apply HEAD. No, he's not doing it anymore. It'd be great if you could resume it. However, I reco

RE: New statistics for tuning WAL buffer size

2020-08-18 Thread Masahiro Ikeda
On 2020-08-18 16:35, tsunakawa.ta...@fujitsu.com wrote: From: Masahiro Ikeda It's important to provide the metrics for tuning the size of WAL buffers. For now, it's lack of the statistics how often processes wait to write WAL because WAL buffer is full. If those situation are often occurred,

RE: New statistics for tuning WAL buffer size

2020-08-18 Thread tsunakawa.ta...@fujitsu.com
From: Masahiro Ikeda > It's important to provide the metrics for tuning the size of WAL buffers. > For now, it's lack of the statistics how often processes wait to write WAL > because WAL buffer is full. > > If those situation are often occurred, WAL buffer is too small for the > workload. > DBA

New statistics for tuning WAL buffer size

2020-08-18 Thread Masahiro Ikeda
Hi, It's important to provide the metrics for tuning the size of WAL buffers. For now, it's lack of the statistics how often processes wait to write WAL because WAL buffer is full. If those situation are often occurred, WAL buffer is too small for the workload. DBAs must to tune the WAL buf