All:
One of the big things missing from the "Introduction" docs is a more
thorough explanation of "How Slony Works". As a DBA or SysAdmin, that's
the first question that I desire to have answered by a manual, and serves
to help me better understand all future operations and procedures,
especially troubleshooting.
For example, in introduction.html, it is stated "namely that Slony-I
operates using triggers", but what we should probably be saying is:
"For every table, sequence, or database object that is replicated, Slony
is able to replicate changes by installing a trigger that catches updates,
inserts, and deletes."
Also, "sl_log" isn't mentioned until Chapter/Page 3 and then again in 7.
However, no mention of the "_${repset}_cluster" schema is made at all
prior to that point. It's mentioned in Ch/Pg 5, but the purpose isn't
explained. Somewhere prior mention of "sl_log_1*", there should be a
paragraph explaining design:
"For every database participating in replication, Slony creates a schema
named "_${repset}_cluster" at initialization time to maintain
configuration and status data. Most specifically, nodes acting as
master/sources maintain a _${repset}_cluster.sl_log_{1,2} table to
log/cache of all changes to master which are to be propagated to slaves."
(or something to that effect, check me)
Also, it's also not explicitly stated anywhere that only Sequences and
Tables are replicated. Although that may seem rudimentary, a it's only
briefly touched on.
It should probably be explicitly stated: "A database consists of Casts,
Languages, Schemas, Tables, Indexes, Constraints, Sequences, Triggers,
Functions, Views, Types, etc.; however Slony only replicates Tables,
Indexes, and Sequences. All other objections constitute DDL changes that
must be manually replicated by the administrator." (or something to that
effect, check me).
Another thing to add to the wishlist: Example real-world scenarios DBAs
may encountered and recommended procedures to follow.
Also, it wouldn't hurt to break out XFig or Dia and add some explanatory
diagrams explaining concepts.
Thoughts?
(And yes, I'm will to help write docs!) >:}
l8r,
~BAS
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