On Fri, Oct 14, 2022 at 11:51:30AM -0700, Nathan Bossart wrote:
> On Fri, Oct 14, 2022 at 12:10:18PM +0530, Bharath Rupireddy wrote:
>> 2) I think we have a problem - set archive_mode and archive_library
>> and start the server, then set archive_command, reload the conf, see
>> [3] - the archiver needs to error out right? The archiver gets
>> restarted whenever archive_library changes but not when
>> archive_command changes. I think the right place for the error is
>> after or at the end of HandlePgArchInterrupts().
>
> Good catch. You are right, this is broken. I believe that we need to
> check for the misconfiguration in HandlePgArchInterrupts() in addition to
> LoadArchiveLibrary(). I will work on fixing this.
As promised...
--
Nathan Bossart
Amazon Web Services: https://aws.amazon.com
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 66312b53b8..9d0f3608c4 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -3597,9 +3597,11 @@ include_dir 'conf.d'
</para>
<para>
This parameter can only be set in the <filename>postgresql.conf</filename>
- file or on the server command line. It is ignored unless
+ file or on the server command line. It is only used if
<varname>archive_mode</varname> was enabled at server start and
- <varname>archive_library</varname> is set to an empty string.
+ <varname>archive_library</varname> is set to an empty string. If both
+ <varname>archive_command</varname> and <varname>archive_library</varname>
+ are set, archiving will fail.
If <varname>archive_command</varname> is an empty string (the default) while
<varname>archive_mode</varname> is enabled (and <varname>archive_library</varname>
is set to an empty string), WAL archiving is temporarily
@@ -3624,7 +3626,9 @@ include_dir 'conf.d'
<para>
The library to use for archiving completed WAL file segments. If set to
an empty string (the default), archiving via shell is enabled, and
- <xref linkend="guc-archive-command"/> is used. Otherwise, the specified
+ <xref linkend="guc-archive-command"/> is used. If both
+ <varname>archive_command</varname> and <varname>archive_library</varname>
+ are set, archiving will fail. Otherwise, the specified
shared library is used for archiving. For more information, see
<xref linkend="backup-archiving-wal"/> and
<xref linkend="archive-modules"/>.
diff --git a/src/backend/postmaster/pgarch.c b/src/backend/postmaster/pgarch.c
index 3868cd7bd3..39c2115943 100644
--- a/src/backend/postmaster/pgarch.c
+++ b/src/backend/postmaster/pgarch.c
@@ -801,7 +801,8 @@ HandlePgArchInterrupts(void)
archiveLibChanged = strcmp(XLogArchiveLibrary, archiveLib) != 0;
pfree(archiveLib);
- if (archiveLibChanged)
+ if (archiveLibChanged ||
+ (XLogArchiveLibrary[0] != '\0' && XLogArchiveCommand[0] != '\0'))
{
/*
* Call the currently loaded archive module's shutdown callback,
@@ -809,17 +810,25 @@ HandlePgArchInterrupts(void)
*/
call_archive_module_shutdown_callback(0, 0);
- /*
- * Ideally, we would simply unload the previous archive module and
- * load the new one, but there is presently no mechanism for
- * unloading a library (see the comment above
- * internal_load_library()). To deal with this, we simply restart
- * the archiver. The new archive module will be loaded when the
- * new archiver process starts up.
- */
- ereport(LOG,
- (errmsg("restarting archiver process because value of "
- "\"archive_library\" was changed")));
+ if (archiveLibChanged)
+ {
+ /*
+ * Ideally, we would simply unload the previous archive module
+ * and load the new one, but there is presently no mechanism
+ * for unloading a library (see the comment above
+ * internal_load_library()). To deal with this, we simply
+ * restart the archiver. The new archive module will be loaded
+ * when the new archiver process starts up.
+ */
+ ereport(LOG,
+ (errmsg("restarting archiver process because value of "
+ "\"archive_library\" was changed")));
+ }
+ else
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("both archive_command and archive_library specified"),
+ errdetail("Only one of archive_command, archive_library may be set.")));
proc_exit(0);
}
@@ -836,6 +845,12 @@ LoadArchiveLibrary(void)
{
ArchiveModuleInit archive_init;
+ if (XLogArchiveLibrary[0] != '\0' && XLogArchiveCommand[0] != '\0')
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("both archive_command and archive_library specified"),
+ errdetail("Only one of archive_command, archive_library may be set.")));
+
memset(&ArchiveContext, 0, sizeof(ArchiveModuleCallbacks));
/*
