I have been looking into this project for a side-by-side upgrade solution. The most widely suggested/used solution is to do a full back of SQL Server 2000 database and restore on SQL Server 2008 with norecovery. Then restore the subsequent transaction log backups with norecovery. When we are ready to switch, change SQL Server 2000 to read-only mode, backup the tail-log and restore it on SQL Server 2008 with recovery. Then bring SQL Server 2008 online.
But, can't the upgrade be done with transactional replication where SQL Server 2000 is the publisher and SQL Server 2008 is the subscriber. Script all objects such as logins, indexes, etc and apply to SQL Server 2008. When we are ready to switch, we will stop replication, delete all replication jobs, and switch all apps to connect to SQL Server 2008. I haven't found anyone that suggests this method. Is there anything wrong with it?
The method of data migration you describe is possible to perform using SQL Server Replication.
There is nothing wrong with this method or any other data migration method for that matter, so long as the choice you decide upon addresses the specific requirements of your project/application platform.
That said the method you describe is certainly more technically involved in both the configuration and implementation of the actual migration steps. If you can accept downtime, a simple backup and restore process is certainly going to be much more straight forward. Log shipping would also be another simpler migration method.
So far, you know that the replication method could work in theory. Now is the time to build out a working solution in test in order to validate your data migration strategy and to practice the implementation process.
If you aren't replicating otherwise, creating a replication subscription will change your schema and a few settings.
For example, you may end up with GUIDs generated for all your rows just to facilitate the replication.
Caution - transactional replication will turn off all IDENTITY columns at the subscriber (the transactional replication SPs actually depend on this fact, as they insert into the IDENTITY columns without first specifying IDENTITY_INSERT ON). I can only confirm this is the case when the subscriber is SQL 2000 as well - perhaps the subscriber on 2008 will behave differently.
For this reason, transactional replication with SQL 2K doesn't really give you a hot standby. We had to do a fair bit of SQL tweaking (re-instating the IDENTITY columns & re-writing the replication SPs with IDENTITY_INSERT wrappers) to get ourselves a situation where the subscriber actually works as a hot standby, ready to have applications pointed at it. But it certainly wouldn't work out of the box =)
Yes, it will work, provided that you transfer the other objects over.
Related
We have an Oracle OLTP system and a SQL Server reporting solution. We run nightly stored procedures to extract the data using linked server but it it very slow as it is transferring millions of records. It would be great to have some transactional replication to get this data into our SQL Server environment in a near real time manner for reporting purposes. Has anyone tried this? Without buying an expensive piece of software what would be the best bet?
We've looked into Apache Kafka to capture the changes and apply them to another database but it seems like a high maintenance approach.
If we switched on CDC on the Oracle side could we write a stored procedure to query the CDC table and make the changes?
Is there a simpler approach that we've overlooked?
We only have read access to the Oracle server but it is managed by a third party that could set up something on our behalf.
Recently I had to implement transactional replication to have a live copy of that database on another server for reporting purposes. While configuring replication I realized that a lot of tables didn't have a primary key, so I could not publish all the tables I wanted to.
Second option was to implement merge replication but that would have added a GUID column to all the tables. Since it is a database for a vendor application and vendor has warned us to not "touch" the database structure because any change in the database structure can cause their application to break. So merge replication is not an option anymore.
I have been doing some research on other available options for me in this scenario; the only thing I could find is Log Shipping. I know it will leave my database in Read-Only mode but (to my knowledge) since this is the only option I am left with and it will be strictly used for Reporting purposes only I think I can live with this.
Can anyone suggest a better solution for this? Or is Log Shipping the only option left for me?
It is SQL Server 2008 R2 64-bit DataCenter Edition.
Your other options are:
Database mirroring, and using a snapshot for read-only operations. It can be a pain to manage snapshots.
Upgrading to SQL Server 2012, and make use of Readable Secondaries in Availability Groups. This can be a pain in the wallet.
You mention log shipping but, based on your follow-up comments I don't think it's clear that, every time you restore a log to the log shipped copy, you need to kick out all of the users that may be running reports. This is because you need exclusive access to the database in order to restore the log. This is another case of "you get what you pay for" - you can log ship to Express instances, if you want to (and if your database supports it), but it's not exactly a watertight solution.
The two servers have exactly the same setup (databases/tables etc). I want one of the tables (on both servers) to have the same data. So the update procedure on server A should also be able to update server B.
I want this to happen with each call to that update stored procedure with out any time delay. Any thoughts?
I did look at the other questions but this aspect of multiple servers seems to be un-answered. Any thoughts?
Edit to clarify: The Server B always should follow Server A. (Also, the stored procedure that updates A can be edited to update B... if the Dbs were on the same server... this is a different case.)
Take a look at SQL Server High Availability solutions. Log Shipping, Failover Cluster, or Database Mirroring may fit your particular needs. It depends whether you need a failover for backup or an online DB for reporting.
Side Note: Database Mirroring will be deprecated in future SQL Server versions and should be avoided. It is being superseded by AlwaysOn Availability Groups in SQL Server 2012.
I have 2 databases that have the same structure, one on a local machine and one on the company's server. Every determined amount of time, the data from the local DB should be synchronized to the server DB.
I have a general idea on how to do this - create a script that somehow "merges" the information that is not on the server DB, then make this script run as a scheduled job for the server. However, my problem lies in the fact that I am not very well experienced with this.
Does SQL Server Management Studio provide an easy way to do this (some kind of wizard) and generates this kind of script? Is this something I'll have to build from scratch?
I've done some basic google searches and came across the term 'Replication' but I don't fully understand it. I would rather hear some input from people who have actually done this or who are good with explaining this kind of stuff.
Thanks.
Replication sounds like a good option for this, but there would be some overhead (not technical overhead, but the knowledge need to support it).
Another SQL Server option is SSIS. SSIS provides graphical tools to design what you're trying to do. The SSIS package can also run SQL statements, if appropriate. An SSIS package can be started, and therefore scheduled, from a SQL Server job.
You should consider the complexity of the synchronization rules when choosing your solution. For example, would it be difficult to resolve conflicts, such as a duplicate key, when merging the data. A SQL script may be easy to create if the rules are simple. But, complex conflict rules may be more difficult to implement in a script (or, replication).
SQL Server Management Studio unfortunately doesn't offer much in this way.
You should have a serious look at some of the excellent commercial offerings out there:
Red Gate Software's SQL Compare and SQL Data Compare - excellent tools, highly recommended! You can even compare a live database against a backup from another database and synchronize the data - pretty nifty!
ApexSQL's SQL Diff and SQL Data Diff
They all cost money - but if you're serious about it, and you use them in your daily routine, they're paid for in no time at all - well worth every dime.
The only "free" option you have in SQL Server 2008 would be to create a link between the two servers and then use something like the MERGE statement (new in SQL Server 2008) to transfer the data. That doesn't work for structural changes, and it's limited only to having a live connection between the two servers.
You should definitely read up on transactional replication. It sounds like a good fit for the situation you've described. Here are a few links to get you started.
How Transactional Replication
Works
How do I... Configure
transactional replication between two
SQL Server 2005 systems?
Performance Tuning SQL Server
Transactional Replication
What you want is Peer-to-Peer Transactional Replication, which allows data to be updated at both databases yet keep them in sync through a contiguous merge of changes. This is the closes match to what you want, but is a fairly costly option (requires Enterprise Edition on both sites). Another option is Bidirectional Transactional Replication, but since this requires also two EE licenses, I say that peer-to-peer is easier to deploy for the same money.
A more budget friendly option is Updatable Subscriptions for Transactional Replication, but updatable subscriptions are being deprecated and you'd bet your money on a loosing horse.
Another option is to use Merge Replication. And finally, for the cases when the 'local' database is quite mobile there is Sync Framework.
Note that all these options require some configuration and cooperation from the Company's server DB.
There are some excellent third party tools out there. For me, xSQL Data Compare has always done the trick. And because the comparisons are highly modifiable it is suitable for almost every data compare or data-synchronization scenario. Hope this helps!
I have two database servers running SQL Server 2005 Enterprise that I want to make one of them as mirror database server.
What I need is; to create an exact copy database from primary server on mirror server, so when the primary server was down, we could switch database IP on application to use mirror server.
I have examined "mirror" feature on SQL Server 2005, and based on this article:
http://aspalliance.com/1388_Database_Mirroring_in_Microsoft_SQL_Server_2005.all
The mirror database cannot be accessed directly; however snapshots of the mirror database can be taken for read only purposes. (Prerequisites no. 4)
So how it can be useful when I can't access it when primary server was down?
I've been thinking about creating a regular backup on primary server and restore it on mirror server on hourly basis, but that's quite inefficient (slow) especially if I want an exact copy (since hundreds data's are added once in minute).
Any other suggestion?
EDIT:
Maybe what I mean was a replication thing, not a mirror (thanks JP for commenting)
They are referring to the fact that you can't perform queries on the mirrored copy, but you can get around that limitation by creating a snapshot of the mirrored database. This is often done to create a read-only database copy for reporting uses. You would have full access of the mirror if the primary were to fail, but it will not failover automatically.
Log shipping is another option, which allows you to query (read-only) the standby database without having to create a snapshot.
If I understand your question correctly, you shouldn't have to do that. There are several role switching forms you can use to have your mirror take over as primary. You don't change the IP address at the application level, the cluster itself has a virtual IP address that allows access to the data at any given time (given a reasonable amount of time for the switch over to the mirror from a primary failure). The mirror stays in synch by itself. :) There are good articles here and here on clustering.
Edit: Okay, based on the comments, check out the various options for replication.
Your confusion is common - there's a lot of ways to do disaster recovery planning with SQL Server. I've recorded a 10-minute video tutorial of SQL Server disaster recovery options including log shipping, mirroring, replication and more. If you like that one, we've got a longer one at Quest called Disaster Recovery Techniques but that one requires registration.
Instead of investigating a specific technology here, what you might want to do is tell us what your needs are, and then we can help you find out what option is right for you. The videos will give you an idea of what kinds of information you need to know before selecting a particular solution.
When using only two SQL Servers, you need to do the fail-over manually. The 'backup' database will be usable after you do two things;
Disable mirroring on it
Restore the database with RECOVERY (but without a backup file, this will make the database usable).
Therefore mirroring in this manner does make scense, however it is hard to maintain;
Moving back from the backup database to the primary is a 'pain' as you have to set-up the complete mirroring again using a backup of the redundant server. This is needed to get the primary back up to speed.
My recommendation would be to get a thrid SQL Server into the picture that can act as a witness. The witness will monitor the status of the mirroring databases. Your bonus; you will get automatic failover, and will not have the fail-over (and after fail-over) issues.
If I remeber correct, the witness server can be running SQL Express so no need for the Enterprise version on all three - just the two where the actual mirroring will take place.
Let me know if you need Transact SQL for the commands to fail-over and 'anti-fail-over' in a two server scenario, and I can dig them up.