Обсуждение: wal_init_zero and wal_recycle
Hi, The group of wal_init_zero and wal_recycle is WAL_SETTINGS in guc.c, but their descriptions are located in "19.6. Replication"/"19.6.1. Sending Servers" section. This seems a documentation bug. They should be located in "19.5. Write Ahead Log"/"19.5.1. Settings". Thought? Regards, -- Fujii Masao Advanced Computing Technology Center Research and Development Headquarters NTT DATA CORPORATION
On Wed, 27 May 2020 at 04:27, Fujii Masao <masao.fujii@oss.nttdata.com> wrote:
Hi,
The group of wal_init_zero and wal_recycle is WAL_SETTINGS in guc.c,
but their descriptions are located in "19.6. Replication"/"19.6.1. Sending
Servers" section. This seems a documentation bug. They should be located
in "19.5. Write Ahead Log"/"19.5.1. Settings". Thought?
+1
Why are there two settings for the same thing (COW support)?
Would we really want to allow setting one but not the other?
On Wed, May 27, 2020 at 7:09 PM Simon Riggs <simon@2ndquadrant.com> wrote: > On Wed, 27 May 2020 at 04:27, Fujii Masao <masao.fujii@oss.nttdata.com> wrote: >> >> Hi, >> >> The group of wal_init_zero and wal_recycle is WAL_SETTINGS in guc.c, >> but their descriptions are located in "19.6. Replication"/"19.6.1. Sending >> Servers" section. This seems a documentation bug. They should be located >> in "19.5. Write Ahead Log"/"19.5.1. Settings". Thought? > > > +1 > > Why are there two settings for the same thing (COW support)? > Would we really want to allow setting one but not the other? In the long discussion[1] we decided to invent GUCs that tell you precisely what they do, rather than trying to have a mysterious "COW filesystem mode", given the apparent lack of COW filesystem expertise in the thread (for example: claims, theories and data about ZFS were presented, but do they also apply to BTRFS, APFS, ReFS, ...? I dunno, and no one showed up with more information on that.) [1] https://www.postgresql.org/message-id/flat/CACPQ5Fo00QR7LNAcd1ZjgoBi4y97%2BK760YABs0vQHH5dLdkkMA%40mail.gmail.com
On 2020/05/28 8:43, Thomas Munro wrote: > On Wed, May 27, 2020 at 7:09 PM Simon Riggs <simon@2ndquadrant.com> wrote: >> On Wed, 27 May 2020 at 04:27, Fujii Masao <masao.fujii@oss.nttdata.com> wrote: >>> >>> Hi, >>> >>> The group of wal_init_zero and wal_recycle is WAL_SETTINGS in guc.c, >>> but their descriptions are located in "19.6. Replication"/"19.6.1. Sending >>> Servers" section. This seems a documentation bug. They should be located >>> in "19.5. Write Ahead Log"/"19.5.1. Settings". Thought? >> >> >> +1 Thanks! Patch attached. Since they are located just before wal_buffers in postgresql.conf.sample, I moved the descriptions of them also just before that of wal_buffers in "Write Ahead Log"/"Settings" section. BTW, while reading guc.c, I found the GUC context of wal_recycle is PGC_SUSET. But isn't it better to set it to PGC_SIGHUP because wal_recycle doesn't affect any backends? Basically checkpointer and startup process use wal_recycle. Regards, -- Fujii Masao Advanced Computing Technology Center Research and Development Headquarters NTT DATA CORPORATION
Вложения
On 2020/05/29 13:13, Fujii Masao wrote: > > > On 2020/05/28 8:43, Thomas Munro wrote: >> On Wed, May 27, 2020 at 7:09 PM Simon Riggs <simon@2ndquadrant.com> wrote: >>> On Wed, 27 May 2020 at 04:27, Fujii Masao <masao.fujii@oss.nttdata.com> wrote: >>>> >>>> Hi, >>>> >>>> The group of wal_init_zero and wal_recycle is WAL_SETTINGS in guc.c, >>>> but their descriptions are located in "19.6. Replication"/"19.6.1. Sending >>>> Servers" section. This seems a documentation bug. They should be located >>>> in "19.5. Write Ahead Log"/"19.5.1. Settings". Thought? >>> >>> >>> +1 > > Thanks! Patch attached. > Since they are located just before wal_buffers in postgresql.conf.sample, > I moved the descriptions of them also just before that of wal_buffers > in "Write Ahead Log"/"Settings" section. Barring any objection, I will commit this patch. Regards, -- Fujii Masao Advanced Computing Technology Center Research and Development Headquarters NTT DATA CORPORATION
On 2020/06/02 14:25, Fujii Masao wrote: > > > On 2020/05/29 13:13, Fujii Masao wrote: >> >> >> On 2020/05/28 8:43, Thomas Munro wrote: >>> On Wed, May 27, 2020 at 7:09 PM Simon Riggs <simon@2ndquadrant.com> wrote: >>>> On Wed, 27 May 2020 at 04:27, Fujii Masao <masao.fujii@oss.nttdata.com> wrote: >>>>> >>>>> Hi, >>>>> >>>>> The group of wal_init_zero and wal_recycle is WAL_SETTINGS in guc.c, >>>>> but their descriptions are located in "19.6. Replication"/"19.6.1. Sending >>>>> Servers" section. This seems a documentation bug. They should be located >>>>> in "19.5. Write Ahead Log"/"19.5.1. Settings". Thought? >>>> >>>> >>>> +1 >> >> Thanks! Patch attached. >> Since they are located just before wal_buffers in postgresql.conf.sample, >> I moved the descriptions of them also just before that of wal_buffers >> in "Write Ahead Log"/"Settings" section. > > Barring any objection, I will commit this patch. Pushed. Thanks! Regards, -- Fujii Masao Advanced Computing Technology Center Research and Development Headquarters NTT DATA CORPORATION