Re: Master/Slave, DB separation or just spend $$$?

kelvinq@gmail.com (Kelvin Quee) writes:
> I will go look at Slony now.

It's worth looking at, but it is not always to be assumed that
replication will necessarily improve scalability of applications; it's
not a "magic wand" to wave such that "presto, it's all faster!"

Replication is helpful from a performance standpoint if there is a lot
of query load where it is permissible to look at *somewhat* out of
date information.

For instance, replication can be quite helpful for pushing load off
for processing accounting data where you tend to be doing analysis on
data from {yesterday, last week, last month, last year}, and where the
data tends to be inherently temporal (e.g. - you're looking at
transactions with dates on them).

On the other hand, any process that anticipates *writing* to the
master database will be more or less risky to try to shift over to a
possibly-somewhat-behind 'slave' system, as will be anything that
needs to be consistent with the "master state."
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