What does it mean by XLOG_BACKUP_RECORD?

On Thu, Jun 29, 2017 at 10:28 AM, Masahiko Sawada <sawada.mshk@gmail.com> wrote:

While reading source codes I found the following comment in xlog.c.

/*
* Have we passed our safe starting point? Note that minRecoveryPoint is
* known to be incorrectly set if ControlFile->backupEndRequired, until
* the XLOG_BACKUP_RECORD arrives to advise us of the correct
* minRecoveryPoint. All we know prior to that is that we're not
* consistent yet.
*/
if (!reachedConsistency && !ControlFile->backupEndRequired &&
minRecoveryPoint <= lastReplayedEndRecPtr &&
XLogRecPtrIsInvalid(ControlFile->backupStartPoint))

What does XLOG_BACKUP_RECORED means by? I could not find such XLOG info value.
Does it mean XLOG_BACKUP_END?

This comment is a thinko, it refers to XLOG_BACKUP_END. This comment
block could be reworded a bit, it looks cleaner to me to say
"ControlFile->backupEndRequired is false" instead of just referring to
the variable itself. Worse, the current comment implies that
minRecoveryPoint is incorrectly set if it is true. Bleh.
--
Michael

On Thu, Jun 29, 2017 at 10:49 AM, Michael Paquier
<michael.paquier@gmail.com> wrote:

On Thu, Jun 29, 2017 at 10:28 AM, Masahiko Sawada <sawada.mshk@gmail.com> wrote:

While reading source codes I found the following comment in xlog.c.

/*
* Have we passed our safe starting point? Note that minRecoveryPoint is
* known to be incorrectly set if ControlFile->backupEndRequired, until
* the XLOG_BACKUP_RECORD arrives to advise us of the correct
* minRecoveryPoint. All we know prior to that is that we're not
* consistent yet.
*/
if (!reachedConsistency && !ControlFile->backupEndRequired &&
minRecoveryPoint <= lastReplayedEndRecPtr &&
XLogRecPtrIsInvalid(ControlFile->backupStartPoint))

What does XLOG_BACKUP_RECORED means by? I could not find such XLOG info value.
Does it mean XLOG_BACKUP_END?

This comment is a thinko, it refers to XLOG_BACKUP_END. This comment
block could be reworded a bit, it looks cleaner to me to say
"ControlFile->backupEndRequired is false" instead of just referring to
the variable itself.

Thanks, I agree to use XLOG_BACKUP_END instead.

Worse, the current comment implies that
minRecoveryPoint is incorrectly set if it is true. Bleh.

Looking at the condition, we use minRecoveryPoint only when
ControlFile->backupEndRequired is *false*. So I guess that it means
that minRecoveryPoint is incorrectly set if
ControlFile->backupEndReuired is true. Am I missing something?

Regards,

--
Masahiko Sawada
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center

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On 6/29/17 06:09, Masahiko Sawada wrote:

Thanks, I agree to use XLOG_BACKUP_END instead.

Worse, the current comment implies that
minRecoveryPoint is incorrectly set if it is true. Bleh.

Looking at the condition, we use minRecoveryPoint only when
ControlFile->backupEndRequired is *false*. So I guess that it means
that minRecoveryPoint is incorrectly set if
ControlFile->backupEndReuired is true. Am I missing something?

I agree with you that the logic in the comment is correct. I've
committed just the symbol change.

--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

On Sat, Dec 9, 2017 at 1:25 AM, Peter Eisentraut
<peter.eisentraut@2ndquadrant.com> wrote:

On 6/29/17 06:09, Masahiko Sawada wrote:

Thanks, I agree to use XLOG_BACKUP_END instead.

Worse, the current comment implies that
minRecoveryPoint is incorrectly set if it is true. Bleh.

Looking at the condition, we use minRecoveryPoint only when
ControlFile->backupEndRequired is *false*. So I guess that it means
that minRecoveryPoint is incorrectly set if
ControlFile->backupEndReuired is true. Am I missing something?

I agree with you that the logic in the comment is correct. I've
committed just the symbol change.

Thank you for picking up an old thread and committing it!

Regards,

--
Masahiko Sawada
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center