Re: [HACKERS] Proposal for a cascaded master-slave replication system

On Wed, Nov 12, 2003 at 02:08:23PM +0100, Hans-J?rgen Sch?nig wrote:

> an inferior product anyway. What I want to point out is that some people
> want an alternative Oracle's Real Application Cluster. They want load
> balancing and hot failover. Even data centers asking for replication did
> not want to have an async approach in the past.

I think Jan has already outlined his more-distant-future idea, but
I'd also like to know whether the people who are asking for a
replacement for RAC are willing to invest in it? You could buy some
_awfully_ good development time for even a year's worth of licensing
for RAC. I get the impression from the Postgres-R list that their
biggest obstacle is development resources.

<rant> People often like to say they need hot-fail-capable, five
nines, 24/7/365 systems. For most applications, I just do not
believe that, and the truth is that the cost of getting from three
nines to four (never mind five) is so great that people cheat: one
paragraph has the "five nines" clause, and the next paragraph talks
about scheduled downtime. In a real "five nines" system (the phone
company, say, or the air traffic control system), the time for
scheduled downtime is just the cumulative possible outage at any node
when it is being switched with its replacement. Five minutes a year
is a pretty high bar to jump, and most people long ago concluded that
you don't actually need it for most applications. </rant>

A

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