Re: [HACKERS] Enforcing that all WAL has been replayed after restoring from backup
On 17.08.2011 12:26, Fujii Masao wrote: So, in master, we should change pg_controldata.c and pg_resetxlog.c for new pg_control field "backupEndRequired"? Ah, good catch! Fixed. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Enforcing that all WAL has been replayed after restoring from backup
On Wed, Aug 17, 2011 at 5:49 PM, Heikki Linnakangas wrote: > Hmm, this behaves slightly differently, if you first try to start the > restored server without recovery.conf, stop recovery, and restart it after > adding recovery.conf. But I guess that's not a big deal, the check is simply > skipped in that case, which is what always happens without this patch > anyway. Oh, I forgot to consider that case. Yeah, I agree with you. > Committed this to 9.1, Thanks a lot! > but kept master as it was. So, in master, we should change pg_controldata.c and pg_resetxlog.c for new pg_control field "backupEndRequired"? > (sorry for the delay, I wanted to fix the bogus comment as soon as I saw it, > but needed some time to ponder the rest of the patch) NM. Thanks! Regards, -- Fujii Masao NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Enforcing that all WAL has been replayed after restoring from backup
On 16.08.2011 04:10, Fujii Masao wrote: On Thu, Aug 11, 2011 at 1:34 AM, Heikki Linnakangas wrote: Hmm, that's not possible for the 'tar' output, but would work for 'dir' output. Another similar idea would be to withhold the control file in memory until the end of backup, and append it to the output as last. The backup can't be restored until the control file is written out. That won't protect from more complicated scenarios, like if you take the backup without the -x flag, and copy some but not all of the required WAL files manually to the pg_xlog directory. But it'd be much better than nothing for 9.1. We need to skip checking whether we've reached the end backup location only when the server crashes while base backup using pg_start_backup. Right? Yes. We can do this by *not* initializing ControlFile->backupStartPoint if the server is doing crash recovery and backupEndRequired is false. What about the attached patch? Hmm, this behaves slightly differently, if you first try to start the restored server without recovery.conf, stop recovery, and restart it after adding recovery.conf. But I guess that's not a big deal, the check is simply skipped in that case, which is what always happens without this patch anyway. Committed this to 9.1, but kept master as it was. (sorry for the delay, I wanted to fix the bogus comment as soon as I saw it, but needed some time to ponder the rest of the patch) -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Enforcing that all WAL has been replayed after restoring from backup
On Thu, Aug 11, 2011 at 1:34 AM, Heikki Linnakangas
wrote:
> Hmm, that's not possible for the 'tar' output, but would work for 'dir'
> output. Another similar idea would be to withhold the control file in memory
> until the end of backup, and append it to the output as last. The backup
> can't be restored until the control file is written out.
>
> That won't protect from more complicated scenarios, like if you take the
> backup without the -x flag, and copy some but not all of the required WAL
> files manually to the pg_xlog directory. But it'd be much better than
> nothing for 9.1.
We need to skip checking whether we've reached the end backup location
only when the server crashes while base backup using pg_start_backup. Right?
We can do this by *not* initializing ControlFile->backupStartPoint if the server
is doing crash recovery and backupEndRequired is false. What about the attached
patch?
Regards,
--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 11035e6..d0d68d4 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6329,11 +6329,8 @@ StartupXLOG(void)
/*
* set backupStartPoint if we're starting recovery from a base backup
*/
- if (haveBackupLabel)
- {
+ if ((InArchiveRecovery && haveBackupLabel) || backupEndRequired)
ControlFile->backupStartPoint = checkPoint.redo;
- ControlFile->backupEndRequired = backupEndRequired;
- }
ControlFile->time = (pg_time_t) time(NULL);
/* No need to hold ControlFileLock yet, we aren't up far enough */
UpdateControlFile();
@@ -6703,20 +6700,13 @@ StartupXLOG(void)
* crashes while an online backup is in progress. We must not treat
* that as an error, or the database will refuse to start up.
*/
- if (InArchiveRecovery || ControlFile->backupEndRequired)
- {
- if (ControlFile->backupEndRequired)
-ereport(FATAL,
- (errmsg("WAL ends before end of online backup"),
- errhint("All WAL generated while online backup was taken must be available at recovery.")));
- else if (!XLogRecPtrIsInvalid(ControlFile->backupStartPoint))
-ereport(FATAL,
- (errmsg("WAL ends before end of online backup"),
- errhint("Online backup started with pg_start_backup() must be ended with pg_stop_backup(), and all WAL up to that point must be available at recovery.")));
- else
-ereport(FATAL,
- (errmsg("WAL ends before consistent recovery point")));
- }
+ if (!XLogRecPtrIsInvalid(ControlFile->backupStartPoint))
+ ereport(FATAL,
+ (errmsg("WAL ends before end of online backup"),
+ errhint("Online backup started with pg_start_backup() must be ended with pg_stop_backup(), and all WAL up to that point must be available at recovery.")));
+ else
+ ereport(FATAL,
+ (errmsg("WAL ends before consistent recovery point")));
}
/*
@@ -8540,7 +8530,6 @@ xlog_redo(XLogRecPtr lsn, XLogRecord *record)
if (XLByteLT(ControlFile->minRecoveryPoint, lsn))
ControlFile->minRecoveryPoint = lsn;
MemSet(&ControlFile->backupStartPoint, 0, sizeof(XLogRecPtr));
- ControlFile->backupEndRequired = false;
UpdateControlFile();
LWLockRelease(ControlFileLock);
@@ -9826,8 +9815,8 @@ read_backup_label(XLogRecPtr *checkPointLoc, bool *backupEndRequired)
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("invalid data in file \"%s\"", BACKUP_LABEL_FILE)));
/*
- * BACKUP METHOD line is new in 9.0. Don't complain if it doesn't exist,
- * in case you're restoring from a backup taken with an 9.0 beta version
+ * BACKUP METHOD line is new in 9.1. Don't complain if it doesn't exist,
+ * in case you're restoring from a backup taken with an 9.1 beta version
* that didn't emit it.
*/
if (fscanf(lfp, "BACKUP METHOD: %19s", backuptype) == 1)
diff --git a/src/include/catalog/pg_control.h b/src/include/catalog/pg_control.h
index 6688c19..9600b50 100644
--- a/src/include/catalog/pg_control.h
+++ b/src/include/catalog/pg_control.h
@@ -137,16 +137,9 @@ typedef struct ControlFileData
* we use the redo pointer as a cross-check when we see an end-of-backup
* record, to make sure the end-of-backup record corresponds the base
* backup we're recovering from.
- *
- * If backupEndRequired is true, we know for sure that we're restoring
- * from a backup, and must see a backup-end record before we can safely
- * start up. If it's false, but backupStartPoint is set, a backup_label
- * file was found at startup but it may have been a leftover from a stray
- * pg_start_backup() call, not accompanied by pg_stop_backup().
*/
XLogRecPtr minRecoveryPoint;
XLogRecPtr backupStartPoint;
- bool backupEndRequired;
/*
* Parameter settings that determine if the WAL can be used for archival
--
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Re: [HACKERS] Enforcing that all WAL has been replayed after restoring from backup
Magnus Hagander writes: >>> Or add a signal >>> handler in the pg_basebackup client emitting a warning about it? >> >> We don't have such a signal handler pg_dump either. I don't think we should >> add it. > > Hmm. I guess an aborted pg_dump will also "look ok but actually be > corrupt" (or incomplete). Good point. What about having the signal handler corrupt the backup by adding some garbage into it? Now the failure case is obvious… Regards, -- Dimitri Fontaine http://2ndQuadrant.fr PostgreSQL : Expertise, Formation et Support -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Enforcing that all WAL has been replayed after restoring from backup
On Wed, Aug 10, 2011 at 19:45, Tom Lane wrote: > Heikki Linnakangas writes: >> Hmm, that's not possible for the 'tar' output, but would work for 'dir' >> output. Another similar idea would be to withhold the control file in >> memory until the end of backup, and append it to the output as last. The >> backup can't be restored until the control file is written out. > >> That won't protect from more complicated scenarios, like if you take the >> backup without the -x flag, and copy some but not all of the required >> WAL files manually to the pg_xlog directory. But it'd be much better >> than nothing for 9.1. > > Maybe we're overcomplicating this. What about changing pg_basebackup to > print a message when the backup is completely sent/received? People > would get used to that quickly, and would know to be suspicious if they > didn't see it. That would suck for scripts, and have people redirect the output to /dev/null instead, wouldn't it? And it violates the "unix expectation" that is that a successful command will not write anything to it's output... -- Magnus Hagander Me: http://www.hagander.net/ Work: http://www.redpill-linpro.com/ -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Enforcing that all WAL has been replayed after restoring from backup
On Wed, Aug 10, 2011 at 1:45 PM, Tom Lane wrote: > Heikki Linnakangas writes: >> Hmm, that's not possible for the 'tar' output, but would work for 'dir' >> output. Another similar idea would be to withhold the control file in >> memory until the end of backup, and append it to the output as last. The >> backup can't be restored until the control file is written out. > >> That won't protect from more complicated scenarios, like if you take the >> backup without the -x flag, and copy some but not all of the required >> WAL files manually to the pg_xlog directory. But it'd be much better >> than nothing for 9.1. > > Maybe we're overcomplicating this. What about changing pg_basebackup to > print a message when the backup is completely sent/received? People > would get used to that quickly, and would know to be suspicious if they > didn't see it. Yeah, but would they be sufficiently suspicious to think "oh, my backup is hopeless corrupted even if it seems to work"? I think a clearer warning is needed, at the very least, and if there's a way to prevent it altogether at least in straightforward cases, that would be even better. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Enforcing that all WAL has been replayed after restoring from backup
Heikki Linnakangas writes: > Hmm, that's not possible for the 'tar' output, but would work for 'dir' > output. Another similar idea would be to withhold the control file in > memory until the end of backup, and append it to the output as last. The > backup can't be restored until the control file is written out. > That won't protect from more complicated scenarios, like if you take the > backup without the -x flag, and copy some but not all of the required > WAL files manually to the pg_xlog directory. But it'd be much better > than nothing for 9.1. Maybe we're overcomplicating this. What about changing pg_basebackup to print a message when the backup is completely sent/received? People would get used to that quickly, and would know to be suspicious if they didn't see it. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Enforcing that all WAL has been replayed after restoring from backup
On 10.08.2011 15:34, Simon Riggs wrote: On Wed, Aug 10, 2011 at 1:19 PM, Robert Haas wrote: On Wed, Aug 10, 2011 at 6:53 AM, Magnus Hagander wrote: On Wed, Aug 10, 2011 at 12:44, Heikki Linnakangas wrote: On 10.08.2011 12:29, Magnus Hagander wrote: On Tue, Aug 9, 2011 at 18:07, Tom Lanewrote: Heikki Linnakangaswrites: On 09.08.2011 18:20, Alvaro Herrera wrote: How about making the new backup_label field optional? If absent, assume current behavior. That's how I actually did it in the patch. However, the problem wrt. requiring initdb is not the new field in backup_label, it's the new field in the control file. Yeah. I think it's too late to be fooling with pg_control for 9.1. Just fix it in HEAD. Should we add a note to the documentation of pg_basebackup in 9.1 telling people to take care about the failure case? Something like "Note: if you abort the backup before it's finished, the backup won't be valid" ? That seems pretty obvious to me, hardly worth documenting. I meant something more along the line of that it looks ok, but may be corrupted. Yeah. I'm frankly pretty nervous about shipping 9.1 with this problem, but note that I don't have a better idea. I'd favor making pg_basebackup emit a warning or maybe even remove the backup if it's aborted midway through. I don't understand why we need to change pg_control for this? Why can't we just add a line to backup_label as the first action of pg_basebackup and then updated it the last action to show the backup set is complete? Hmm, that's not possible for the 'tar' output, but would work for 'dir' output. Another similar idea would be to withhold the control file in memory until the end of backup, and append it to the output as last. The backup can't be restored until the control file is written out. That won't protect from more complicated scenarios, like if you take the backup without the -x flag, and copy some but not all of the required WAL files manually to the pg_xlog directory. But it'd be much better than nothing for 9.1. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Enforcing that all WAL has been replayed after restoring from backup
On Wed, Aug 10, 2011 at 1:19 PM, Robert Haas wrote: > On Wed, Aug 10, 2011 at 6:53 AM, Magnus Hagander wrote: >> On Wed, Aug 10, 2011 at 12:44, Heikki Linnakangas >> wrote: >>> On 10.08.2011 12:29, Magnus Hagander wrote: On Tue, Aug 9, 2011 at 18:07, Tom Lane wrote: > > Heikki Linnakangas writes: >> >> On 09.08.2011 18:20, Alvaro Herrera wrote: >>> >>> How about making the new backup_label field optional? If absent, >>> assume >>> current behavior. > >> That's how I actually did it in the patch. However, the problem wrt. >> requiring initdb is not the new field in backup_label, it's the new >> field in the control file. > > Yeah. I think it's too late to be fooling with pg_control for 9.1. > Just fix it in HEAD. Should we add a note to the documentation of pg_basebackup in 9.1 telling people to take care about the failure case? >>> >>> Something like "Note: if you abort the backup before it's finished, the >>> backup won't be valid" ? That seems pretty obvious to me, hardly worth >>> documenting. >> >> I meant something more along the line of that it looks ok, but may be >> corrupted. > > Yeah. I'm frankly pretty nervous about shipping 9.1 with this > problem, but note that I don't have a better idea. I'd favor making > pg_basebackup emit a warning or maybe even remove the backup if it's > aborted midway through. I don't understand why we need to change pg_control for this? Why can't we just add a line to backup_label as the first action of pg_basebackup and then updated it the last action to show the backup set is complete? That would be safe for 9.1 -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Enforcing that all WAL has been replayed after restoring from backup
On Wed, Aug 10, 2011 at 6:53 AM, Magnus Hagander wrote: > On Wed, Aug 10, 2011 at 12:44, Heikki Linnakangas > wrote: >> On 10.08.2011 12:29, Magnus Hagander wrote: >>> >>> On Tue, Aug 9, 2011 at 18:07, Tom Lane wrote: Heikki Linnakangas writes: > > On 09.08.2011 18:20, Alvaro Herrera wrote: >> >> How about making the new backup_label field optional? If absent, >> assume >> current behavior. > That's how I actually did it in the patch. However, the problem wrt. > requiring initdb is not the new field in backup_label, it's the new > field in the control file. Yeah. I think it's too late to be fooling with pg_control for 9.1. Just fix it in HEAD. >>> >>> Should we add a note to the documentation of pg_basebackup in 9.1 >>> telling people to take care about the failure case? >> >> Something like "Note: if you abort the backup before it's finished, the >> backup won't be valid" ? That seems pretty obvious to me, hardly worth >> documenting. > > I meant something more along the line of that it looks ok, but may be > corrupted. Yeah. I'm frankly pretty nervous about shipping 9.1 with this problem, but note that I don't have a better idea. I'd favor making pg_basebackup emit a warning or maybe even remove the backup if it's aborted midway through. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Enforcing that all WAL has been replayed after restoring from backup
On Wed, Aug 10, 2011 at 12:44, Heikki Linnakangas wrote: > On 10.08.2011 12:29, Magnus Hagander wrote: >> >> On Tue, Aug 9, 2011 at 18:07, Tom Lane wrote: >>> >>> Heikki Linnakangas writes: On 09.08.2011 18:20, Alvaro Herrera wrote: > > How about making the new backup_label field optional? If absent, > assume > current behavior. >>> That's how I actually did it in the patch. However, the problem wrt. requiring initdb is not the new field in backup_label, it's the new field in the control file. >>> >>> Yeah. I think it's too late to be fooling with pg_control for 9.1. >>> Just fix it in HEAD. >> >> Should we add a note to the documentation of pg_basebackup in 9.1 >> telling people to take care about the failure case? > > Something like "Note: if you abort the backup before it's finished, the > backup won't be valid" ? That seems pretty obvious to me, hardly worth > documenting. I meant something more along the line of that it looks ok, but may be corrupted. >> Or add a signal >> handler in the pg_basebackup client emitting a warning about it? > > We don't have such a signal handler pg_dump either. I don't think we should > add it. Hmm. I guess an aborted pg_dump will also "look ok but actually be corrupt" (or incomplete). Good point. -- Magnus Hagander Me: http://www.hagander.net/ Work: http://www.redpill-linpro.com/ -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Enforcing that all WAL has been replayed after restoring from backup
On 10.08.2011 12:29, Magnus Hagander wrote: On Tue, Aug 9, 2011 at 18:07, Tom Lane wrote: Heikki Linnakangas writes: On 09.08.2011 18:20, Alvaro Herrera wrote: How about making the new backup_label field optional? If absent, assume current behavior. That's how I actually did it in the patch. However, the problem wrt. requiring initdb is not the new field in backup_label, it's the new field in the control file. Yeah. I think it's too late to be fooling with pg_control for 9.1. Just fix it in HEAD. Should we add a note to the documentation of pg_basebackup in 9.1 telling people to take care about the failure case? Something like "Note: if you abort the backup before it's finished, the backup won't be valid" ? That seems pretty obvious to me, hardly worth documenting. Or add a signal handler in the pg_basebackup client emitting a warning about it? We don't have such a signal handler pg_dump either. I don't think we should add it. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Enforcing that all WAL has been replayed after restoring from backup
On Tue, Aug 9, 2011 at 18:07, Tom Lane wrote: > Heikki Linnakangas writes: >> On 09.08.2011 18:20, Alvaro Herrera wrote: >>> How about making the new backup_label field optional? If absent, assume >>> current behavior. > >> That's how I actually did it in the patch. However, the problem wrt. >> requiring initdb is not the new field in backup_label, it's the new >> field in the control file. > > Yeah. I think it's too late to be fooling with pg_control for 9.1. > Just fix it in HEAD. Should we add a note to the documentation of pg_basebackup in 9.1 telling people to take care about the failure case? Or add a signal handler in the pg_basebackup client emitting a warning about it? -- Magnus Hagander Me: http://www.hagander.net/ Work: http://www.redpill-linpro.com/ -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Enforcing that all WAL has been replayed after restoring from backup
On 09.08.2011 19:07, Tom Lane wrote: Heikki Linnakangas writes: On 09.08.2011 18:20, Alvaro Herrera wrote: How about making the new backup_label field optional? If absent, assume current behavior. That's how I actually did it in the patch. However, the problem wrt. requiring initdb is not the new field in backup_label, it's the new field in the control file. Yeah. I think it's too late to be fooling with pg_control for 9.1. Just fix it in HEAD. Done. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Enforcing that all WAL has been replayed after restoring from backup
Heikki Linnakangas writes: > On 09.08.2011 18:20, Alvaro Herrera wrote: >> How about making the new backup_label field optional? If absent, assume >> current behavior. > That's how I actually did it in the patch. However, the problem wrt. > requiring initdb is not the new field in backup_label, it's the new > field in the control file. Yeah. I think it's too late to be fooling with pg_control for 9.1. Just fix it in HEAD. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Enforcing that all WAL has been replayed after restoring from backup
On 09.08.2011 18:20, Alvaro Herrera wrote: Excerpts from Heikki Linnakangas's message of mar ago 09 05:00:00 -0400 2011: I think this is a nice additional safeguard to have, making streamed backups more robust. I'd like to add this to 9.1, but it required an extra field to be added to the control file, so it would force an initdb. It's probably not worth that. Or, we could sneak in the extra boolean field to some currently unused pad space in the ControlFile struct. How about making the new backup_label field optional? If absent, assume current behavior. That's how I actually did it in the patch. However, the problem wrt. requiring initdb is not the new field in backup_label, it's the new field in the control file. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Enforcing that all WAL has been replayed after restoring from backup
Excerpts from Heikki Linnakangas's message of mar ago 09 05:00:00 -0400 2011: > I think this is a nice additional safeguard to have, making streamed > backups more robust. I'd like to add this to 9.1, but it required an > extra field to be added to the control file, so it would force an > initdb. It's probably not worth that. Or, we could sneak in the extra > boolean field to some currently unused pad space in the ControlFile struct. How about making the new backup_label field optional? If absent, assume current behavior. -- Álvaro Herrera The PostgreSQL Company - Command Prompt, Inc. PostgreSQL Replication, Consulting, Custom Development, 24x7 support -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
