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<p class=MsoNormal><font size=2 face=Arial><span lang=EN-AU style='font-size:
10.0pt'>Hi,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-AU style='font-size:
10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-AU style='font-size:
10.0pt'>If this is not an appropriate forum for these comments, please let me
know the best place to propose enhancements to functionality.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-AU style='font-size:
10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-AU style='font-size:
10.0pt'>Here’s my basic problem with slony and why I think it is not yet “industrial
strength”:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-AU style='font-size:
10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-AU style='font-size:
10.0pt'>Despite what the home page says, Slony is absolutely not a clustering
solution. It is a replication solution. For any database to have
true high availability (achievable 24/7 up time), it must have a clustering
solution. Put simply, a cluster has these things:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-AU style='font-size:
10.0pt'><o:p> </o:p></span></font></p>
<ol style='margin-top:0cm' start=1 type=1>
<li class=MsoNormal style='mso-list:l0 level1 lfo1'><font size=2 face=Arial><span
lang=EN-AU style='font-size:10.0pt'>A cluster is comprised of any number
of servers that behaves like a single server and that is addressable by a
single consistent address<o:p></o:p></span></font></li>
<li class=MsoNormal style='mso-list:l0 level1 lfo1'><font size=2 face=Arial><span
lang=EN-AU style='font-size:10.0pt'>A server may be added to the cluster
at any time without any downtime. When a server is added, it brings
itself up to date automatically<o:p></o:p></span></font></li>
<li class=MsoNormal style='mso-list:l0 level1 lfo1'><font size=2 face=Arial><span
lang=EN-AU style='font-size:10.0pt'>A server may be removed from the
cluster at any time without any downtime<o:p></o:p></span></font></li>
<li class=MsoNormal style='mso-list:l0 level1 lfo1'><font size=2 face=Arial><span
lang=EN-AU style='font-size:10.0pt'>The failure of a server is detected by
the cluster and it is automatically excluded from the cluster without any downtime<o:p></o:p></span></font></li>
</ol>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-AU style='font-size:
10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-AU style='font-size:
10.0pt'>Basically, you can add and remove servers whenever you like, and because
there’s no single point of failure, it can stay up 24/7.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-AU style='font-size:
10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-AU style='font-size:
10.0pt'>Slony can not do any of these things. That’s why I don’t
use postgres for the transaction system – we have a 24/7 operation and we
can’t guarantee achieving our SLAs with postgres.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-AU style='font-size:
10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span lang=EN-AU
style='font-size:10.0pt;color:black'>Regards,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span lang=EN-AU
style='font-size:10.0pt;color:black'>Glen<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span lang=EN-AU
style='font-size:10.0pt;color:black'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 face=Arial><span lang=EN-AU style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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