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Allow the postmaster to accept changes in PGC_BACKEND GUC variables

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from the config file, so that these changes will propagate to backends
started later.  Already-started backends continue to ignore changes
in these variables.
This commit is contained in:
Tom Lane
2001-09-30 20:16:21 +00:00
parent e43d51fddc
commit f00da6d841
3 changed files with 58 additions and 41 deletions
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72
src/backend/utils/misc/guc.c
View File

@ -4,7 +4,7 @@
* Support for grand unified configuration scheme, including SET
* command, configuration file, and command line options.
*
* $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.54 2001/09/30 18:57:45 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.55 2001/09/30 20:16:21 tgl Exp $
*
* Copyright 2000 by PostgreSQL Global Development Group
* Written by Peter Eisentraut <peter_e@gmx.net>.
@ -704,37 +704,49 @@ set_config_option(const char *name, const char *value,
* precise rules. Note that we don't want to throw errors if we're in
* the SIGHUP context. In that case we just ignore the attempt.
*/
if (record->context == PGC_POSTMASTER && context != PGC_POSTMASTER)
switch (record->context)
{
if (context != PGC_SIGHUP)
elog(ERROR, "'%s' cannot be changed after server start", name);
else
return true;
case PGC_POSTMASTER:
if (context == PGC_SIGHUP)
return true;
if (context != PGC_POSTMASTER)
elog(ERROR, "'%s' cannot be changed after server start", name);
break;
case PGC_SIGHUP:
if (context != PGC_SIGHUP && context != PGC_POSTMASTER)
elog(ERROR, "'%s' cannot be changed now", name);
/*
* Hmm, the idea of the SIGHUP context is "ought to be global, but
* can be changed after postmaster start". But there's nothing
* that prevents a crafty administrator from sending SIGHUP
* signals to individual backends only.
*/
break;
case PGC_BACKEND:
if (context == PGC_SIGHUP)
{
/*
* If a PGC_BACKEND parameter is changed in the config file,
* we want to accept the new value in the postmaster (whence
* it will propagate to subsequently-started backends), but
* ignore it in existing backends. This is a tad klugy, but
* necessary because we don't re-read the config file during
* backend start.
*/
if (IsUnderPostmaster)
return true;
}
else if (context != PGC_BACKEND && context != PGC_POSTMASTER)
elog(ERROR, "'%s' cannot be set after connection start", name);
break;
case PGC_SUSET:
if (context == PGC_USERSET || context == PGC_BACKEND)
elog(ERROR, "permission denied");
break;
case PGC_USERSET:
/* always okay */
break;
}
else if (record->context == PGC_SIGHUP && context != PGC_SIGHUP &&
context != PGC_POSTMASTER)
{
elog(ERROR, "'%s' cannot be changed now", name);
/*
* Hmm, the idea of the SIGHUP context is "ought to be global, but
* can be changed after postmaster start". But there's nothing
* that prevents a crafty administrator from sending SIGHUP
* signals to individual backends only.
*/
}
else if (record->context == PGC_BACKEND && context != PGC_BACKEND
&& context != PGC_POSTMASTER)
{
if (context != PGC_SIGHUP)
elog(ERROR, "'%s' cannot be set after connection start", name);
else
return true;
}
else if (record->context == PGC_SUSET &&
(context == PGC_USERSET || context == PGC_BACKEND))
elog(ERROR, "permission denied");
/*
* Evaluate value and set variable

13
src/include/utils/guc.h
View File

@ -4,7 +4,7 @@
* External declarations pertaining to backend/utils/misc/guc.c and
* backend/utils/misc/guc-file.l
*
* $Id: guc.h,v 1.9 2001/06/18 16:14:43 momjian Exp $
* $Id: guc.h,v 1.10 2001/09/30 20:16:21 tgl Exp $
*/
#ifndef GUC_H
#define GUC_H
@ -23,11 +23,12 @@
* certain point in their main loop. It's safer to wait than to read a
* file asynchronously.)
*
* BACKEND options can only be set at postmaster startup or with the
* PGOPTIONS variable from the client when the connection is
* initiated. Note that you cannot change this kind of option using
* the SIGHUP mechanism, that would defeat the purpose of this being
* fixed for a given backend once started.
* BACKEND options can only be set at postmaster startup, from the
* configuration file, or with the PGOPTIONS variable from the client
* when the connection is initiated. Furthermore, an already-started
* backend will ignore changes to such an option in the configuration
* file. The idea is that these options are fixed for a given backend
* once it's started, but they can vary across backends.
*
* SUSET options can be set at postmaster startup, with the SIGHUP
* mechanism, or from SQL if you're a superuser. These options cannot