Slony1 PostgreSQL Replication - multiple database help

Author

multiple database help

Victoria Parsons

2005-06-24, 9:24 am

I am fairly new to slony and need a quick help.

I have my first database replicating to mulitple slaves. I now want to add another database replicating with the same origin and slaves. I thought I could add it as a new set (my first and only set contains all tables from myfirst db) but I have just realised that a node is tied to a database. So my question is, should I add more nodes to the cluster with the same connection hosts as the first set but the new database name, or should I create a new cluster. I assume with a new cluster I'll need to have run slony twice for each host, once for each cluster.

Thanksk for your help,
Vicki

____________________
____________________
__________

Victoria Parsons
victoria.parsons- UVxggvuNoGJxTUc3asy8
/Q@public.gmane.org

This message should be regarded as confidential. If you have received this email in error please notify the sender and destroy it immediately.
Statements of intent shall only become binding when confirmed in hard copy by an authorized signatory.

--
This message has been scanned for all known viruses
and dangerous content by StreamShield Protector,
and has been found to be clean.

Tim Goodaire

2005-06-24, 9:24 am

____________________
____________________
_______
Slony1-general mailing list
Slony1-general- AuKwsB3Fm+ugFIWk8tvy
RWD2FQJk+8+b@public.gmane.org
http://gborg.postgresql.org/mailman.../slony1-general

Victoria Parsons

2005-06-24, 11:25 am

Thanks for that info. Another question:=0D

If lots of database changes happen in "very quick" succession on the origin=
node, so that they are all replicated during the same SYNC, are they guara=
nteed to be replicated out in the true order they happened?=0D

Cheers,=0D
Vicki=0D

-----Original Message-----=0D
From: slony1-general-bounces- AuKwsB3Fm+ugFIWk8tvy
RWD2FQJk+8+b@public.gmane.org=0D
[mailto:slony1-general-bounces- AuKwsB3Fm+ugFIWk8tvy
RWD2FQJk+8+b@public.gmane.org]On Behalf Of Tim=0D
Goodaire=0D
Sent: 24 June 2005 14:24=0D
To: slony1-general- AuKwsB3Fm+ugFIWk8tvy
RWD2FQJk+8+b@public.gmane.org=0D
Subject: Re: [Slony1-general] multiple database help=0D

On Fri, Jun 24, 2005 at 02:15:28PM +0100, Victoria Parsons wrote:=0D

> I am fairly new to slony and need a quick help.=0D

> =0D

> I have my first database replicating to mulitple slaves. I now want to=
add=0D

> another database replicating with the same origin and slaves. I though=
t I=0D

> could add it as a new set (my first and only set contains all tables f=
rom=0D

> my first db) but I have just realised that a node is tied to a databas=
e.=0D

Right. =0D

> So my question is, should I add more nodes to the cluster with the sam=
e=0D

> connection hosts as the first set but the new database name, or should=
I=0D

> create a new cluster. =0D

You'll have to create a new cluster.=0D

> I assume with a new cluster I'll need to have run=0D

> slony twice for each host, once for each cluster.=0D

You'll need to run a slon for each node in the two clusters.=0D

Tim=0D

> =0D

> Thanksk for your help,=0D

> Vicki=0D

> =0D

> ____________________
____________________
__________=0D

> =0D

> Victoria Parsons=0D

> victoria.parsons- UVxggvuNoGJxTUc3asy8
/Q@public.gmane.org=0D

> =0D

> This message should be regarded as confidential. If you have received =
this=0D

> email in error please notify the sender and destroy it immediately.=0D

> Statements of intent shall only become binding when confirmed in hard =
copy=0D

> by an authorized signatory.=0D

> =0D

> =0D

> =0D

> This message has been scanned for all known viruses and dangerous content=
by=0D

> [1]StreamShield Protector, and has been found to be clean.=0D

> =0D

> References=0D

> =0D

> Visible links=0D

> 1. http://www.streamshield.com/=0D

> ____________________
____________________
_______=0D

> Slony1-general mailing list=0D

> Slony1-general- AuKwsB3Fm+ugFIWk8tvy
RWD2FQJk+8+b@public.gmane.org=0D

> http://gborg.postgresql.org/mailman...ony1-general=0D

-- =0D

Tim Goodaire 416-673-4126 tgoodair-swQf4SbcV9C7WVzo/KQ3Mw@public.gmane.org=0D

Database Administrator, Afilias Canada Corp.=0D

--=20
This message has been scanned for viruses and potentially
harmful content by StreamShield Protector.

Christopher Browne

2005-06-24, 11:25 am

Victoria Parsons wrote:

>Thanks for that info. Another question:
>
>If lots of database changes happen in "very quick" succession on the origin node, so that they are all replicated during the same SYNC, are they guaranteed to be replicated out in the true order they happened?
>
>
Yes, they surely are.

There is an "actionseq" column on sl_log_1 which is used to indicate the
order in which changes are applied.

Jan Wieck

2005-06-25, 11:23 am

On 6/24/2005 12:13 PM, Christopher Browne wrote:

> Victoria Parsons wrote:
>
> Yes, they surely are.
>
> There is an "actionseq" column on sl_log_1 which is used to indicate the
> order in which changes are applied.

There could be race conditions where the after trigger doing the
replication log collection is effectively fired in a different order
than the row updates really happened with respect to concurrent
transactions. But since concurrent transactions would block each other
in the case of conflicting updates, the resulting replication action
order is guaranteed to be in an agreeable order that leads to the same
end result. And since all changes of one SYNC are applied in one
transaction, nobody can see intermediate states, so nobody can actually
tell that things got applied in a slightly different order.

Jan

--
#===================
====================
====================
===========#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me. #
#===================
====================
=========== JanWieck- bwPqjjyvM7QAvxtiuMwx
3w@public.gmane.org #

Sponsored Links