Would you buy a car without an instrument panel?
“Naw, don’t worry about fuel or oil or speed,” says the salesman. “We’ve found that those things make people worry unnecessarily, so we’ve left them out. Cars get along fine without them.”
Of course, you know that’s bull. You can’t drive safely or calmly when you don’t know whether you have a sudden oil pressure problem, how fast you’re going or how little fuel you have left.
So why would you perform a database migration or upgrade without a way to know how it’s going?
Source and target databases get out of sync
Think about the things that can go wrong when you’re migrating Oracle databases: stale records, application changes, application errors that have gone unnoticed and updates from ongoing user activity, to name just a few. Out-of-sync conditions like those can occur during any kind of data movement. They all boil down to the biggest risk of the entire project: that target doesn’t equal source.
That’s important because if tables in your target get out of sync, then you’re not replicating the data the way you think you are. When the data on the target is different from that on the source, reporting problems may arise and cause the replication to abort due to errors. Worse yet, your customers and users could begin working with the wrong data.
If source and target databases get out of sync in the middle of an Oracle migration or upgrade, then you won’t really be sure what you’ve ended up with at the end of the project, will you?
“Migration finished?” asks a senior manager or your CIO.
“Yep,” you answer.
“Did all the data come over?”
“How do you know?”
What will you say to that? How will you know that all your data came over successfully?
Detecting and repairing errors
That’s why the single most important feature you could ask for in a database replication tool is error detection, to compare source and target databases at any point during the migration. And, if they are out of sync for some reason, you’ll want to receive notification and re-synchronize data on the target with the data on the source.
Your goal is to keep source and target in sync. You don’t want to have to impose downtime on the entire migration project while you resolve an out-of-sync situation.
If you don’t like surprises while you’re driving (like running out of gas or being cited for speeding), then you really do need the instrument panel. And if you want to be sure that your source and target databases are synchronized, your database replication tool should include real-time error detection.
Simplify Your Database Migrations and Upgrades – e-Book series
Continuing our e-book series titled “Simplify Your Database Migrations and Upgrades,” we’ve released part 3 on database replication tools including Oracle GoldenGate and SharePlex. You’ll learn about detecting out-of-sync conditions and maintaining the integrity of source and target databases throughout your migration projects. Give it a read and see how a database replication tool can facilitate your upgrades and migrations.