On Wed, Jan 5, 2011 at 10:06 PM, Emmanuel Lécharny <elecharny@apache.org> wrote:
On 1/5/11 8:17 PM, Alex Karasulu wrote:
On Wed, Jan 5, 2011 at 8:13 PM, Emmanuel Lecharny<elecharny@gmail.com>wrote:

On 1/5/11 6:49 PM, Alex Karasulu wrote:

So when considering compatibility we have to consider several things
besides
just APIs and SPIs:

  o Database Format
  o Schema
  o Replication Mechanism
  o Configuration
  o API Compatibility
  o Plugins - We have pseudo plugins like Partitions, Interceptors and
Handlers that users can alter which involve SPIs.

I would get the Database Format and Configuration out of the equation. It's
up to us to provide tools to migrate from one format to the other. Don't get
me wrong : when I say that configuration is out of the equation, I mean that
the configuration can change, not its format (ie switching from XML to DIT
is possible between to major releases, not between two minor releases).


Will this be transparent to the user? Meaning can he just upgrade the
software and the migration will occur without any change in their workflow,
or anything noticeable in performance, wait time on startup? More
specifically:

(1) Does the user have to run a tool to migrate from one version to the next
?

Definitively, yes.


This is a bit worrisome to me but I cannot figure out why yet. Something in my gut that I have not translated into real consequences yet.

I can see advantages with such a tool which allows us to change these formats and configurations. But the disadvantage is the one off of having to figure out if you need the tool with every minor or micro release. It's yet another one off and the tool make take a day to run depending on how big the DIB is.

However with modularity and OSGi these points become less problematic.

If this is set as the policy then this tool must always be provided. Those who push this as the way then need to be held responsible for providing the tool when needed. That sort of goes against the community dynamic: it's going to be a must do for those accepting the policy.  

So for those who want it, it should be provided by them on demand before any release takes place. That's kind of harsh.

Instead if we respect the DB format and just release with the right versioning schemes then we should be OK. If compatibility breaks then a major release can be done and tools can still be provided to migrate optionally without requirement.

See my point here?

(2) If a user has 100 Million entries and there's a migration operation
running with this take say a few hours to start up the server?
This should be a low level tool, so it should act on the Backend interface level


Yeah but it can still take days depending on the DB size but should not be an issue with 90% of our users.

--
Alex Karasulu
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