SQL Server and Oracle, which one is better in terms of scalability? [closed]

Answer 1

Both Oracle and SQL Server are shared-disk databases so they are constrained by disk bandwidth for queries that table scan over large volumes of data. Products such as Teradata, Netezza or DB/2 Parallel Edition are 'shared nothing' architectures where the database stores horizontal partitions on the individual nodes. This type of architecture gives the best parallel query performance as the local disks on each node are not constrained through a central bottleneck on a SAN.

Shared disk systems (such as Oracle Real Application Clusters or Clustered SQL Server installations still require a shared SAN, which has constrained bandwidth for streaming. On a VLDB this can seriously restrict the table-scanning performance that is possible to achieve. Most data warehouse queries run table or range scans across large blocks of data. If the query will hit more than a few percent of rows a single table scan is often the optimal query plan.

Multiple local direct-attach disk arrays on nodes gives more disk bandwidth.

Having said that I am aware of an Oracle DW shop (a major european telco) that has an oracle based data warehouse that loads 600 GB per day, so the shared disk architecture does not appear to impose unsurmountable limitations.

Between MS-SQL and Oracle there are some differences. IMHO Oracle has better VLDB support than SQL server for the following reasons:

• Oracle has native support for bitmap indexes, which are an index structure suitable for high speed data warehouse queries. They essentially do a CPU for I/O tradeoff as they are run-length encoded and use relatively little space. On the other hand, Microsoft claim that Index Intersection is not appreciably slower.

• Oracle has better table partitioning facilities than SQL Server. IIRC The table partitioning in SQL Server 2005 can only be done on a single column.

• Oracle can be run on somewhat larger hardware than SQL Server, although one can run SQL server on some quite respectably large systems.

• Oracle has more mature support for Materialized views and Query rewrite to optimise relational queries. SQL2005 does have some query rewrite capability but it is poorly documented and I haven't seen it used in a production system. However, Microsoft will suggest that you use Analysis Services, which does actually support shared nothing configurations.

Unless you have truly biblical data volumes and are choosing between Oracle and a shared nothing architecture such as Teradata you will probably see little practical difference between Oracle and SQL Server. Particularly since the introduction of SQL2005 the partitioning facilities in SQL Server are viewed as good enough and there are plenty of examples of multi-terabyte systems that have been successfully implemented on it.

Answer 2

When you get to OBSCENE database sizes (where over 1TB is really big enough, and 500TB is frigging massive), then operational support must come very high up on the list of requirements. With that much data, you don't mess about with penny pinching system specifications.

How are you going to backup that size of system? Upgrade the OS and patch the database? Scalability and reliability a concern?

I have experience of both Oracle and MS SQL, and for the really really big systems (users, data or importance) then Oracle is better designed for operational support and data management.

Every tried to backup and restore a 1TB+ SQL Server database split over multiple databases on multiple instances with transaction log files being spat out everywhere by each database and trying to keep it all in sync? Good luck with that.

With Oracle, you have ONE database (so I disagree with the "shared nothing" approach is better) with ONE set of REDO logs(1) and one set of archive logs(2) and you can just add extra hardware nodes without changing (i.e. repartitioning) you application and data.

(1) Redo logs are, of course, mirrored. (2) Archive logs are, of course, stored in multiple locations.

Answer 3

Whether Oracle or MSSQL will scale / perform better is question #15. The data model is the first make-it or break-it item regardless of if you're running Oracle, MSSQL, Informix or anything else. Data model structure, what kind of applicaiton, how it accesses the db etc, which platform your developers know well enough to target for a large system etc are the first questions you should ask yourself.

Answer 4

oracle people will tell you oracle is better, sql server peopele will tell you sql server is better. i say they scale pretty much the same. use what you know better. you have databases out there that are that size on oracle as well as sql server

Answer 5

It would also depend on what is your application meant for. If it uses only Inserts with very few updates, then I think MSSQL would be more scalable and better in terms of performance. However if one has lots of updates, then Oracle would scaleup better

Answer 6

When you are talking 500TB, that is (a) big and (b) specialized. I'd be going to a consultancy firm with appropriate specialists to look at the existing skill sets, integration with existing technology stacks, expected usage, backup/recovery/DR requirements....

In short, it's not the sort of project I'd be heading into based on opinions from stackoverflow. No offence intended, but there's simply too many factors to take into account, a lot of which would be business confidential.