Subject: pgsql: Remove replicaiton FAQ item.

From: [email-masked] (Bruce Momjian)
Date: Sun, 14 Nov 2004 21:33:11 +0000 (GMT)

Log Message:
-----------
Remove replicaiton FAQ item.

Modified Files:
--------------
    pgsql/doc:
        FAQ (r1.269 -> r1.270)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/FAQ.diff?r1=1.269&r2=1.270)
    pgsql/doc/src/FAQ:
        FAQ.html (r1.227 -> r1.228)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/FAQ/FAQ.html.diff?r1=1.227&r2=1.228)

---

From: Robert Treat <[email-masked]>
Date: Tue, 16 Nov 2004 00:32:07 -0500

On Sunday 14 November 2004 16:33, Bruce Momjian wrote:
> (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/FAQ.diff?r1=1.269&r2=
>1.270) pgsql/doc/src/FAQ:

While the answer may have been a little dated, this still seems to be an FAQ.  
Was there a discussion on removing this?  If so I'll go read that, but ISTM 
this question should remain. 

-- 
Robert Treat
Build A Brighter Lamp :: Linux Apache {middleware} PostgreSQL

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From: "Marc G. Fournier" <[email-masked]>
Date: Tue, 16 Nov 2004 23:31:58 -0400 (AST)

> this question should remain.

agreed, this definitly does fall under a "Very FAQ" kinda thing ... 
pointers to the various methods that are currently in use, at a minimum, 
would be good ...

----
Marc G. Fournier           Hub.Org Networking Services (http://www.hub.org)
Email: [email-masked]           Yahoo!: yscrappy              ICQ: 7615664

---

From: Bruce Momjian <[email-masked]>
Date: Wed, 1 Dec 2004 17:26:11 -0500 (EST)

I am thinking of adding a replication section to the main docs rather
than have it in the FAQ.  It would be part of the external
tools/interfaces section I want to add to 8.0 (during our RC period).

---------------------------------------------------------------------------

Marc G. Fournier wrote:
> ---------------------------(end of broadcast)---------------------------
> TIP 8: explain analyze is your friend
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-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  [email-masked]               |  (610) 359-1001
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---

From: "Marc G. Fournier" <[email-masked]>
Date: Wed, 1 Dec 2004 19:44:21 -0400 (AST)

> tools/interfaces section I want to add to 8.0 (during our RC period).

Even then, a FAQ entry should be added to point to that section ... IMHO 
...

----

---

From: Bruce Momjian <[email-masked]>
Date: Wed, 1 Dec 2004 21:19:34 -0500 (EST)

> Even then, a FAQ entry should be added to point to that section ... IMHO 

Yes, once the section is done we can point to it.

---

From: Bruce Momjian <[email-masked]>
Date: Sun, 24 Apr 2005 08:01:05 -0400 (EDT)

> pointers to the various methods that are currently in use, at a minimum, 

Yep, big mistake my removing the replication FAQ item. I have re-added a
new one:

	4.21) What replication solutions are available?
	
	Though "replication" is a single term, there are two major replication
	technologies. Multi-master replication allows read/write queries to be
	sent to multiple replicated computers. Using this capability has a
	serious performance impact. Pgcluster is the most popular such solution
	available for PostgreSQL. Master-slave replication allows a single
	master to receive read/write queries, with slaves able to accept only
	read/SELECT queries. The most popular master-slave PostgreSQL
	replication solution is Slony. There are also commercial and
	hardware-based replication solutions available.

---

From: Christopher Browne <[email-masked]>
Date: Sun, 24 Apr 2005 12:11:13 -0400

> 	hardware-based replication solutions available.

A suggestion for rewording:

Though "replication" is a single term, there are a number of
approaches and technologies to handle it, and thus, for different
purposes, a number of replication systems are available.

Master/slave replication allows a single master to receive read/write
queries, where slaves can only accept read/SELECT queries.  The most
popular freely available master-slave PostgreSQL replication solution
is Slony-I.

Multi-master replication allows read/write queries to be sent to
multiple replicated computers.  Using this capability generaly has a
fairly severe impact on performance due to the need to synchronize
changes between servers.  Pgcluster is the most popular such solution
freely available for PostgreSQL.

There are also commercial and hardware-based replication solutions
available supporting a variety of replication models.
-- 
(format nil "~S@~S" "cbbrowne" "acm.org")
http://linuxdatabases.info/info/slony.html
"It   can be   shown   that for any  nutty  theory,  beyond-the-fringe
political view or  strange religion there  exists  a proponent  on the
Net. The proof is left as an exercise for your kill-file."
-- Bertil Jonell

---

From: Jeff Davis <[email-masked]>
Date: Sun, 24 Apr 2005 11:04:42 -0700

Should the text include a mention of synchronous vs. asynchronous? Or
does master-master imply synchronous?

Regards,
	Jeff Davis

---

From: "Joshua D. Drake" <[email-masked]>
Date: Sun, 24 Apr 2005 11:40:50 -0700

> does master-master imply synchronous?

It shouldn't. It is possible to have synchronous replication without it
being master<->master.

Sincerely,

Joshua D. Drake

---

From: Bruce Momjian <[email-masked]>
Date: Sun, 24 Apr 2005 18:54:29 -0400 (EDT)

> It shouldn't. It is possible to have synchronous replication without it

We could mention async vs sync but at the FAQ stage I think the
multi-master/master-slave disinction is enough. Let's see what questions
we get.

---

From: Mischa Sandberg <[email-masked]>
Date: Sun, 24 Apr 2005 16:15:06 -0700

> multi-master/master-slave disinction is enough. Let's see what 
 
About all you can say is, it is not possible to implement synchronous 
master-master replication, because of conflict resolution of 
simultaneous transactions. 
-- 
"Dreams come true, not free." -- S.Sondheim, ITW

---

From: Bruce Momjian <[email-masked]>
Date: Sun, 24 Apr 2005 19:24:36 -0400 (EDT)

> simultaneous transactions. 

You mean asynchronous master-master?  There are some implementations
(Sybase?, pgreplicator) that do this and have conflict resolution.

---

From: Mischa Sandberg <[email-masked]>
Date: Sun, 24 Apr 2005 17:04:21 -0700

> (Sybase?, pgreplicator) that do this and have conflict resolution. 
 
Forgive my kibitz, then; perhaps my head has been stuck in sand a 
while. You're right, I forgot about the nicer bits of Sybase 
RepServer. Synchronous replication was scratched early in the project, 
because two-phase commit took too long across a dozen db servers. 
 
Pgreplicator advertises itself as a "store-and-forward asynch replica 
(sic) engine." (quoth http://pgreplicator.sourceforge.net/ ) 
--  
"Dreams come true, not free." -- S.Sondheim, ITW

---

From: Bruce Momjian <[email-masked]>
Date: Fri, 29 Apr 2005 23:52:26 -0400 (EDT)

OK, updated:

    <P>Though "replication" is a single term, there are several technologies
    for doing replication, with advantages and disadvantages for each.</P>

    <P>Master/slave replication allows a single master to receive read/write
    queries, while slaves can only accept read/<SMALL>SELECT</SMALL> queries.
    The most popular freely available master-slave PostgreSQL replication
    solution is <A href="http://gborg.postgresql.org/project/slony1/projdisplay$
    Slony-I</A>.</P>

    <P>Multi-master replication allows read/write queries to be sent to
    multiple replicated computers.  This capability also has a severe
    impact on performance due to the need to synchronize changes between
    servers.  <A href="http://pgfoundry.org/projects/pgcluster/">Pgcluster</a>
    is the most popular such solution freely available for PostgreSQL.</P>

    <P>There are also commercial and hardware-based replication solutions
    available supporting a variety of replication models.</P>

Christopher Browne wrote:
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> 
>                http://archives.postgresql.org
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