Re: fdatasync performance problem with large number of DB files

On Tue, May 25, 2021 at 07:13:59PM -0500, Justin Pryzby wrote:
> On Sat, Mar 20, 2021 at 12:16:27PM +1300, Thomas Munro wrote:
> > > > + {
> > > > + {"recovery_init_sync_method", PGC_POSTMASTER, ERROR_HANDLING_OPTIONS,
> > > > + gettext_noop("Sets the method for synchronizing the data directory before crash recovery."),
> > > > + },
>
> Is there any reason why this can't be PGC_SIGHUP ?
> (Same as restart_after_crash, remove_temp_files_after_crash)

I can't see any reason why this is nontrivial.
What about data_sync_retry?

commit 2d2d2e10f99548c486b50a1ce095437d558e8649
Author: Justin Pryzby <pryzbyj(at)telsasoft(dot)com>
Date: Sat May 29 13:41:14 2021 -0500

Change recovery_init_sync_method to PGC_SIGHUP..

The setting has no effect except during startup.
But it's nice to be able to change the setting dynamically, which is expected
to be pretty useful to an admin following crash recovery when turning the
service off and on again is not so appealing.

See also: 2941138e6, 61752afb2

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d8c0fd3315..ab9916eac5 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -9950,7 +9950,8 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir'
appear only in kernel logs.
</para>
<para>
- This parameter can only be set at server start.
+ This parameter can only be set in the <filename>postgresql.conf</filename>
+ file or on the server command line.
</para>
</listitem>
</varlistentry>
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 87bc688704..796b4e83ce 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -4945,7 +4945,7 @@ static struct config_enum ConfigureNamesEnum[] =
},

{
- {"recovery_init_sync_method", PGC_POSTMASTER, ERROR_HANDLING_OPTIONS,
+ {"recovery_init_sync_method", PGC_SIGHUP, ERROR_HANDLING_OPTIONS,
gettext_noop("Sets the method for synchronizing the data directory before crash recovery."),
},
&recovery_init_sync_method,
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index ddbb6dc2be..9c4c4a9eec 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -774,7 +774,6 @@
# data?
# (change requires restart)
#recovery_init_sync_method = fsync # fsync, syncfs (Linux 5.8+)
- # (change requires restart)


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