Any alternative communication for dblink a 9iR2 and a 10gR2 on same unix?

Question

I want to access tables of a 9iR2 with a 10gR2 sql function(ora_hash). is there any better alternative for dblink access in performance perspective?
or is there any tricks to create the dblink for two instances on the same unix?
thank you.

Answer 1

At what point are you going to to do the validation?after complete sync of databases we were given 2 hours of downtime for validation, parallel to some configuration on application servers and some user acceptance tests Justin.
If the hash doesn't match, what are you going to do? You can't go back to the old system without losing transactions made on the new system. And you can't easily figure out which rows don't match (and why) from a single hash value.we will be doing MINUS ALL over dblink to see the details of the difference, hashing is like a boolean flag, so we will be only interested for the ones that have a false flag with hashing.
what is the back-out plan? we are not letting go the platform A databases until everything is validated successfully. they will be opened restricted and read-only. another important point is when there is a need of going back after some hours or days on the platform B, for this purposes we will be again capturing the changes on the target databases in order to apply them back to the source databases in any unexpected case may occur after some time we opened the customer channels.
Do you really need a hash that combines every row? Could you not pick a reasonable and representative sample of rows to verify that the changes came across (i.e. by forcing updates to Dummy Customer A-Z records at various "interesting" points during the transition and verifying that the changes come over)?ora_hash is fast, it runs on SQL engine, we can generate count and hash values within an hour for over 10 TB of data with our hardware for now. So we didn't need sampling yet.
Obviously, you can do the validation in the lower environments because you don't have to run 24x7 there. Is that level of validation not sufficient? If something works in dev, test, and staging, do you really need to do the full validation in production?as always dev. and test environments are not %100 representative for a production, we are doing tests but I am nearly sure that we will see new things when we go for production :)