Re: [HACKERS] Standby Mode

2006-08-03 Thread Simon Riggs
On Wed, 2006-08-02 at 18:49 -0400, Tom Lane wrote:
 Simon Riggs [EMAIL PROTECTED] writes:
  [I have an outstanding question on how to include LWlock support into
  the archiver, required to flesh out the feature set, and of course
  assuming these patches being accepted.]
 
 The archiver is deliberately designed not to be connected to shared
 memory.  If you want to change that you'll have to make a very strong
 case why we should give up the safety and security advantages of it.

We should let the user decide. 

If archiver_timeout is a server start GUC then we can attach to shared
memory if it is set, if not we avoid that.

If they are in a position to want that functionality they can make that
trade-off.

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  Simon Riggs
  EnterpriseDB  http://www.enterprisedb.com


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Re: [HACKERS] Standby Mode

2006-08-03 Thread Tom Lane
Simon Riggs [EMAIL PROTECTED] writes:
 On Wed, 2006-08-02 at 18:49 -0400, Tom Lane wrote:
 The archiver is deliberately designed not to be connected to shared
 memory.  If you want to change that you'll have to make a very strong
 case why we should give up the safety and security advantages of it.

 We should let the user decide. 

Really?  The way we let the user decide whether to run as root or not?
I don't think we make security-related decisions that way.

You haven't actually explained what you want this for, so the entire
discussion is operating in a vacuum ...

regards, tom lane

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Re: [HACKERS] Standby Mode

2006-08-03 Thread stark
Tom Lane [EMAIL PROTECTED] writes:

 Simon Riggs [EMAIL PROTECTED] writes:
 On Wed, 2006-08-02 at 18:49 -0400, Tom Lane wrote:
 The archiver is deliberately designed not to be connected to shared
 memory.  If you want to change that you'll have to make a very strong
 case why we should give up the safety and security advantages of it.

 We should let the user decide. 

 Really?  The way we let the user decide whether to run as root or not?
 I don't think we make security-related decisions that way.

Well there is also precedent the other way, namely fsync.

I think the key factor is, is it a decision the user may know more about than
we do. In the case of fsync the user may well know that the data isn't
important (yet) such as in the case of an initial database load. In general I
would say security decisions are more prone rather than less to having this
property.

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  Gregory Stark
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Re: [HACKERS] Standby Mode

2006-08-02 Thread Josh Berkus
Simon,

How close do your PITR patches take us to Oracle's Standby Databases?  
I'm trying to decide whether it's a major features for PR purposes or 
not.

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Josh Berkus
PostgreSQL @ Sun
San Francisco

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Re: [HACKERS] Standby Mode

2006-08-02 Thread Simon Riggs
On Wed, 2006-08-02 at 13:05 -0700, Josh Berkus wrote:

 How close do your PITR patches take us to Oracle's Standby Databases?  
 I'm trying to decide whether it's a major features for PR purposes or 
 not.

That was pretty much the sweet spot I was aiming at. Many databases
support such functionality.

Oracle supports five gradations of functionality, of which we hit first
two. There is a sixth level also, which we can hit using Hannu's ideas
but thats a roll-your own for now.

It would be fair to say that we may support Standby Databases with
asynchronous log file shipping. 

[I have an outstanding question on how to include LWlock support into
the archiver, required to flesh out the feature set, and of course
assuming these patches being accepted.]

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  EnterpriseDB  http://www.enterprisedb.com


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Re: [HACKERS] Standby Mode

2006-08-02 Thread Tom Lane
Simon Riggs [EMAIL PROTECTED] writes:
 [I have an outstanding question on how to include LWlock support into
 the archiver, required to flesh out the feature set, and of course
 assuming these patches being accepted.]

The archiver is deliberately designed not to be connected to shared
memory.  If you want to change that you'll have to make a very strong
case why we should give up the safety and security advantages of it.

regards, tom lane

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Re: [HACKERS] Standby Mode

2006-08-01 Thread Tom Lane
Josh Berkus josh@agliodbs.com writes:
 Diogo's xlogviewer stuff should be ready shortly also (1-3 weeks). Since
 that's a contrib module how do we stand on having that get into 8.2,
 even though it isn't going to hit the main feature freeze?

 This is why I was asking for status reports on pgsql-students 10 days ago.  

We've never had a policy of 12:00 AM is the deadline, 1:00 AM is too
late.  However, a week or two late is getting towards too late.  The
entire point of the feature-freeze deadline is to push the pghackers
community out of develop cool stuff mode, and into fix what you
broke, and how about some documentation and regression tests? mode.
The train is leaving the station, real soon.

regards, tom lane

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Re: [HACKERS] Standby Mode

2006-07-31 Thread Bruce Momjian

Seems you completed most of the PITR items.  That will make great
additions for 8.2.

---

Simon Riggs wrote:
 The restartableRecovery patch introduces the concept of standby_mode,
 where you define in the recovery.conf file that this server is acting as
 a log-shipping target. We can extend that concept to a few other useful
 places.
 
 We've discussed a number of times that we can use a script that waits
 indefinitely for a log file. On reflection, it seems fairly trivial to
 put this directly into the backend. I've got a number of possible
 designs:
 
 1. standby_mode tests to see if restore_command fails, if so it will
 test for a notification_file then loops back round for the
 restore_command again. When a failover occurs the failure-sensing
 mechanism writes the notification file and we bring up the standby.
 
 2. standby_timeout - potentially usable in conjunction with
 archive_timeout. The standby server loops while waiting for the
 restore_command to work until it gets to standby_timeout seconds, then
 automatically comes up in standby mode. Sounds great, but possibly
 slightly less useful since there's no explicit instruction to perform
 failover.
 
 Both of those are very easy to implement, now that I've seen how, and
 would augment the other functionality recently delivered for 8.2.
 
 What does the panel think? Take the red pill, or stick with blue?
 
 -- 
   Simon Riggs
   EnterpriseDB  http://www.enterprisedb.com
 
 
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Re: [HACKERS] Standby Mode

2006-07-31 Thread Simon Riggs
On Mon, 2006-07-31 at 20:34 -0400, Bruce Momjian wrote:
 Seems you completed most of the PITR items.  That will make great
 additions for 8.2.

Diogo's xlogviewer stuff should be ready shortly also (1-3 weeks). Since
that's a contrib module how do we stand on having that get into 8.2,
even though it isn't going to hit the main feature freeze?

I'll be able to spend more time with him on that now.

Do we care whether that's part of the release or not? It's a pretty
specific tool.

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  EnterpriseDB  http://www.enterprisedb.com


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Re: [HACKERS] Standby Mode

2006-07-31 Thread Bruce Momjian
Simon Riggs wrote:
 On Mon, 2006-07-31 at 20:34 -0400, Bruce Momjian wrote:
  Seems you completed most of the PITR items.  That will make great
  additions for 8.2.
 
 Diogo's xlogviewer stuff should be ready shortly also (1-3 weeks). Since
 that's a contrib module how do we stand on having that get into 8.2,
 even though it isn't going to hit the main feature freeze?

I think we would allow a /contrib tool during freeze, especially since
it is a debugging tool and not something that you use for queries.

 I'll be able to spend more time with him on that now.
 
 Do we care whether that's part of the release or not? It's a pretty
 specific tool.

True.  We could put it on pgfoundry and let him make improvements to it
during the 8.2 cycle (faster than we can), and then roll it into 8.3. 
One idea is to put the URL of the pgfoundry project in our
documentation.

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  Bruce Momjian   [EMAIL PROTECTED]
  EnterpriseDBhttp://www.enterprisedb.com

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Re: [HACKERS] Standby Mode

2006-07-31 Thread Josh Berkus
Simon,

 Diogo's xlogviewer stuff should be ready shortly also (1-3 weeks). Since
 that's a contrib module how do we stand on having that get into 8.2,
 even though it isn't going to hit the main feature freeze?

This is why I was asking for status reports on pgsql-students 10 days ago.  

I guess the question is, will it be *production-ready* in 3 weeks, or just 
ready to be tested?


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PostgreSQL @ Sun
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Re: [HACKERS] Standby Mode

2006-07-31 Thread Bruce Momjian
Josh Berkus wrote:
 Simon,
 
  Diogo's xlogviewer stuff should be ready shortly also (1-3 weeks). Since
  that's a contrib module how do we stand on having that get into 8.2,
  even though it isn't going to hit the main feature freeze?
 
 This is why I was asking for status reports on pgsql-students 10 days ago.  
 
 I guess the question is, will it be *production-ready* in 3 weeks, or just 
 ready to be tested?

At this point we are making no promises that it will be in 8.2.  It is
possible if we like it in the future, and see no downside, but at this
point, just assume it will not be in 8.2.

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  Bruce Momjian   [EMAIL PROTECTED]
  EnterpriseDBhttp://www.enterprisedb.com

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