Slony1 PostgreSQL Replication - some questions from new user

Author

some questions from new user

Vincent Chen

2005-08-11, 1:28 pm

Hi, all

I just setup a postgresql cluster and some questions come to me:

1. slon running on foreground and keep showing logs, how can I configure =
slon
run on background as daemon?

2. my test environment has 1 master and 1 slave node. if I need to add an=
other
slave node, how can I do that?

3. mysql also has replication ability. what's the difference between thes=
e 2
DBMS cluster solution?

Thanks,

Vincent Chen

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http://messenger.yahoo.com.tw/

Christopher Browne

2005-08-11, 1:28 pm

Vincent Chen wrote:

>Hi, all
>
>I just setup a postgresql cluster and some questions come to me:
>
>1. slon running on foreground and keep showing logs, how can I configure slon
>run on background as daemon?
>
>
Typically, we write wrapper scripts to start the slon.

>2. my test environment has 1 master and 1 slave node. if I need to add another
>slave node, how can I do that?
>
>
There's no such thing as a "master node" or a "slave node." They are all
just nodes.

If you need to add another node, then...
1. Copy the schema over to the new database,
2. Use STORE NODE to initialize the new database as a Slony-I node
3. Use SUBSCRIBE SET to subscribe the new node to your replication set(s).

>3. mysql also has replication ability. what's the difference between these 2
>DBMS cluster solution?
>
>
I haven't used the MySQL replication system so can't comment on it
meaningfully.

But when cooking, I find that starting with good quality ingredients
turns out a lot better than grabbing ingredients of dubious integrity.
The latter may be satisfactory for generating some sort of stew to which
one adds heavy spices so you can't taste the ingredients.

I'd generally rather start cooking my database applications with
PostgreSQL...

Scott Marlowe

2005-08-22, 11:24 am

On Tue, 2005-08-09 at 21:04, Vincent Chen wrote:
> Hi, all
>
> I just setup a postgresql cluster and some questions come to me:
>
> 1. slon running on foreground and keep showing logs, how can I configure slon
> run on background as daemon?

There are some scripts that come with slon to do that.

> 2. my test environment has 1 master and 1 slave node. if I need to add another
> slave node, how can I do that?

I'm pretty sure this is handled in the basic documentation. And as
someone else mentioned, there is not master and slave, just subscribers
and providers.

> 3. mysql also has replication ability. what's the difference between these 2
> DBMS cluster solution?

Slony works reliably? Just do a search on google or the mysql mailing
lists for reports of mysql replication failing mysteriously, with no
error messages or anything.

Also, slony allows you to take a live db, apply replication, get the
subscriber up to speed, and then switch over with minimal downtime.

MySQL requires you to down the master, make the slave an exact copy, and
then start them both up. Any problem with replication will require you
to repeat this process. ugh.

Slony is a well thought out, third or so generation of replication for
PostgreSQL, and it's designers learned from the mistakes made in
previous replication systems.

MySQL's replication had to get out the door because marketing said so,
bumps and warts and all. They're mostly all still there.

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