Why would you use Oracle database? [closed] - database

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I'm curious for technical reasons why you choose Oracle database versus the latest flavors of:
1) Microsoft SQL Server
2) MySQL
3) PostgreSQL
What features or functionality justify the extra cost.
I'm interested in technical arguments, not a religious war.
A friend asked me this and I've always used one of the 3 I listed.
I didn't know enough about Oracle Databases to offer an opinion.
Thanks.

Noone seems to talk about the cost of developers time working with Oracle. Most developers who know any other db hate Oracle, those that don't assume that all DB code and/or ORM tools are difficult to use.
If I started a business that I believed was going to scale to Amazon proportions I might consider NoSQL solutions, otherwise I'd choose PostgreSQL, SQL Server (or indeed even Sybase now) over Oracle every time. I say this having worked (as a dev) with Oracle for 2 years - its terrible to work with!

Only Oracle and Microsoft's SQLServer are closed source, and when something goes wrong and you have a problem the answer is just a phone call away (and cash if course). Anyways MySQL and PostGre have several enterprise consulting services but in the end these consultants aren't really resposible for the product, because the product belongs to everyone. Which is great because you can go in and fix the code if you are good with C and relatively lowlevel programming, but if you aren't finding the solution might become a wild goose chase.
Now since not everyone is skilled enough, and those enterprises with money prefer the security (in the business sense) of the closed source databases, is the reason why these solutions haven't gone out of business, besides the fact that their implementations are solid and worth the money if you have it.
Ok now finally the most important difference is between SQLServer and Oracle and that difference is the OS, most people using Windows will stick with, you guessed it, SQLServer, but if you run on flavors of Unix Oracle is your closed source solution. Anyways I use Oracle on Solaris, but if our target were Windows I would probably use SQLServer because both products are rock solid, but I trust Microsoft has some special tricks under the hood to get the best performance on windows.

Just to name a few:
Oracle Real Application Cluster - provides advanced clustering features
Oracle Data Guard - in short provides physical and logical stand-by features.
Oracle Exadata - implements the database aware storage (that can do predicate filtering, column projection filtering, join processing, hastens tablespace creation). The solution comes with HP servers, full 24/7 warranty, and other nice things. It's quite nice for applications with highly intensive data loading (for example thanks to the independent tablespace creation).
Oracle Virtualization
And of course the magic of the brand ;)
And when it comes to choosing the RDBMS? Usually the choice is pretty obvious - Oracle or the rest of the world. After that you can narrow the choice down by:
platform (windows-only or not)
weight (sqlite, MySQL, PostgreSQL, ...)
budget (initial license cost, maintenance + support cost)
evolution perspectives, for example:
Oracle Express -> Oracle
SQL Server Express -> MSSQL
business perspectives - "secure, well known product" or open-source product (bear in mind the quotation around the first phrase). Other post tends to look deeper into this aspect.

The real question is, what kind of application is going to be used to make use of a RDMS. You certainly don't need oracle for your wordpress blog or twitter clone. But if you want to do some heavy business intelligence, then Oracle might have some features which can help doing that more efficiently than the others.
Ms sql server is very good aswell, it has tons of features. If you are struck on linux and you need a database with features as offered by ms sql, then oracle would be a good pick.

I think it's because Oracle was the first RDMS that supported "sharding"

The costs of SQL Server and Oracle are not that far apart, you know.
In fact for small systems the cost of Oracle vs Your Favourite Free Database is between zero (Oracle Express Edition) and not-very-big ($5,800 processor perpetual for Standard Edition One).
Here's a link to the capabilities of the various editions in 11g: http://www.oracle.com/database/product_editions.html.
List prices are available for all territories at http://store.oracle.com -- typically large companies do not pay retail, of course ;)

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SQL Server: fundamental design issue? [closed]

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Closed 11 years ago.
The director of the company I work for met another director of a software company at a party (this is not a joke !).
The second director told my director that,
'he had spent a fortune abandoning SQL Server' because 'if several people were querying the same table in different ways the database locked up'. Further, this is a 'known fundamental design issue with SQL Server where each query competes for maximum resources until SQL Server locks up after about 7 concurrent queries to the same table'.
Now I know a bit about SQL Server locking and IO and this is news to me. AFAIK there is nothing inherent in the SQL Server architectur that causes such problems. And SQL Server performs well in the TPC benchmarks, esp on price/performance.
Feel embarrassed asking but I have to be sure - is there any grain of truth to what he said ?
EDIT - after reading some of the comments I thought Id make it clear that I agree its possible to write poorly performing sql in Sql Server, as it is on any db platform. Sort of asking if there is anyting inherent in the architecture that blocks it out under certain high concurrency conditions irrespective of how well your db/sql is crafted?
There is absolutely no truth to this, and the other director clearly had one of the following two scenarios in his IT department, which can be found at very many firms:
No DBA, or the (idiot) director was the DBA, or someone with no DBA qualifications whatsoever was forced to act as the DBA
An incompetent DBA or incompetent IT employees who created the DB schema(s) and queried the database in incompetent ways given those schemas. Also, see TomTom's comment to this answer below, which expands and expounds on this item further.
Also, do have a look at SQL Server's market dominance at the moment, before coming to any conclusions of its inability to do something.
That is not to say that SQL Server is perfect and has no "fundamental design issues," such as for example this unbelievable bug you can encounter when using identity columns which practically everybody does for surrogate keys:
SCOPE_IDENTITY() sometimes returns incorrect value
I know you can lock up SQL accidentally or with some poorly written queries but I wouldnt say it is a design flaw with SQL Server itself.
I have worked on software that was going to be deployed across the UK, 80+ stores all querying the same tables and never had any problems. Our company also produced way larger software built on a SQL database which would have 100s of stores with anything from 10 - 100+ applications all querying / updating the same tables, we had a few issues with deadlock but they were all resolved.
With the right people and knowledge SQL is an amazing tool, when you get any old programmer and make them the DBA you get problems which I suspect has happened here.
When I hear stories like this unless the person telling me is developing some huge enterprise level application I always think if big business can manage to use this application without it giving them huge problems then me saying I cant use SQL in my smaller application is just me doing it wrong.
It would be interesting to know what they migrated to instead of SQL though.
Poorly written queries can result in the behavior he is talking about. This is not a reason to abandon SQL Server though, it is a reason to look for better developers/DBAs.
Any technology, when used incorrectly can appear to have problems. There are a number of huge projects out there that are built on SQL Server (including StackOverflow). If what he was describing were a result of SQL Server and not the developers then SQL Server would most likely not even be around...

What database to use for big data storage and manipulation?

I have to make a decision of which database server to use for my next project, but the simple decision to use MySQL like almost all the projects I did is harder now, because I expect very much records.
The database will store a user list, some other irrelevant tables, and the last one, some user-collected data. Let's say, if I have 6000 users responding to a quiz about each other. Simple math shows that from those users, if each one completes the quiz about everyone (and in my project that is 99% sure that will happen) I'll end up with 35.99million records(they will exclude themselves and in this particular situation the operation is 6000*5999). Unfortunately 6000 maybe is a small number, the real one growing day by day.
What to choose? MySQL and maybe if things go well and the project grows to expand it in a cluster? PostgreSQL, MSSQL? Oracle?
I've read about all of them, each one has it's pros and cons, but still don't know what to choose. The advantage of MySQL and PostgreSQL is of course, the starting price of $0 which is pretty nice in a usual self-funded startup.
Any opinions, pieces of advice? If you encountered this situation in your experience as developers, I'd love to hear from you.
These days, free isn't something that differenciates between databases any more. Both Oracle and SQL Server have free versions, but the limitations is resources - 4 GB database, RAM & single CPU utilization. Millions of records is not a concern - it's what datatypes you're using.
I saw the OPs comment about not liking MS software - that's your prerogative, but using the free versions of either Oracle or SQL Server do benefit from seamless transition to upscale versions of the respective database.
Personally, my choice would be either Oracle or SQL Server because of IMHO, real feature considerations like hierarchical query support, subquery factoring/CTE, packages (long before I get concerned with functions/procedures), full text searching, xml support, etc.
MySQL will handle 35 million records no problem. Worry about scalability when you get there. You can easily add raid hard disks backing your database tables, and if you really start getting big you can get a compellant SAN that will scream... Don't worry about the DB engine as much as the underlying hardware.. MySQL rocks for us with millions of records.
I've had no problems handling tables as large as 36,000,000 rows on MySQL and Oracle.
Just be sure that you index the proper columns, run EXPLAINs for your queries, and maintain proper design principles.
Most of the truly large scale web properties use a distributed key-value store. That said, 35 million is large, but not that large. With most modern databases, your main two scaling worries should be throughput and what happens when no single box can contain your entire database anymore. And both of these problems can be solved to some degree for any database you choose to use. (Caching, replication, sharding, etc.)
Use MySQL until you can't anymore. At that point, you ought to be rolling in dough anyways and you now have a very desirable problem.
Use MySQL as it's free and you have experience with it.
Besides in my opinion it matters more on how you design the tables than which database you use.
35 million records can be easily handled by MS SQL Server (assuming proper database design, indices, etc.). You can start with the free SQL Server Express edition and later, if you need, you can upgrade to the full version which supports clustering, etc.
SQL Server Express does have some limitations - single CPU, 1 GB memory, max 4 GB database size and a few other things. I'm not sure how quickly these limitations will become a problem but you can always move to the full version when you run into them.
MySQL(i) & Postgre
0$ of costs
large community
many tutorials
well documentated
MSSQL
You can get "money" from MS if you promote that you are using MSSQL (secret information from some companies I worked for)
MS tools work very well
Complete tool set from C# IDE over .NET lib to Windows Server 2003
Oracle
Professional and commercial provider
Used by many large companies (I also heard about Blizzard (World of Warcraft) using Oracle)
- expensive
The final decision depends on the very special requirements of your project.
Make yourself a quick list of things , that ARE IMPORTANT for your project (e.g. quick performed queries) and look up which Database pros are matching the most to your requirements.
Everything is about design. SQL Database are some kind of cars, you just have to know which component has to be placed here and which there.
Make a clear design and you won't struggle with any of them.
May be you can test Firebird
Blog post about big Firebird database here
MySQL licence is here (not allways free).
Postgresql and Firebird are free.
First of all, don't think about performance. Premature optimization being the root of all evil and all that. You can always throw more hardware and/or tuning at it later.
All of the mentioned should perform nicely if tuned/maintained correctly. I'd focus on manageability and familiarity. IMHO open source databases excels on manageability (perhaps not the best GUIs, but the CLI has been my home for a long long time).
And if the database becomes the bottleneck, why limit yourself to those choices? How about a key-value distributed database? Or perhaps serialize data directly to disk? Storing data outside of a RDBMS, while often frowned upon, might be the correct path. Or simply use the common route of denormalization.
Always remember not to optimize prematurely.
As far as opinions go (since you specifically asked for it) I favor open source databases, specifically PostgreSQL. It's rock solid, fast and very well-featured. And even with (relatively) large datasets it has performed superbly on mediocre hardware (some tuning involved, of course, but you can't skip that step no matter which db you end up choosing).

How long does it take to become reasonably proficient in Oracle given SQL Server [closed]

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In applying for jobs via agents I sometimes get blocked by an agent who says do you know software package X. When I reply that I know the similar package Y they might say unless you know X I cannot put you forward.
The problem is that some of these agents don't know what they talking about, they are merely being used by their clients as a screening filter.
It would be useful to be able to say to these agents that because I know Y I can expect to become reasonably proficient in X in a given number of days/months. However not knowing X determining the required time is why I'm asking this question.
Most recently X was Oracle and Y was SQL Server.
Please can those of you who know both, express an opinion on how long is required to become reasonably proficient? NB I'm not talking about becoming a DBA!
I'll state my bias upfront - Oracle is far more complex than Sql Server. So it depends what you'll be asked to do. You say that this is not for a DBA position but that definition is pretty fluid. At my company, Developers are charged with designing tables, adding the correct indexes, determining partitioning.
If you say, all I'll do is code in java or c# and call packages written by a DBA or Oracle Developer, then you are safe.
But if you take all of your MSSS experience and add semi-colons to the end of your lines you'll kill your Oracle instance. Many standard practices in MSSS are anethema to Oracle. In MSSS it's recommended to have clustered indexes on most every table. In Oracle we build IOTs (Index Organized Tables) only for specific purposes. In MSSS doing DDL in T-SQL is as easy as falling off a log. In Oracle it is made difficult on purpose, it's discouraged and in fact somewhat dangerous. In MSSS you whip off #temp table like they're jelly beans, in Oracle we plan them in advance since they are permanent database objects that aren't just created in the middle of a proc when the logic gets a little tricky.
That said, would you be able to make Oracle do something? Well, yah, but the real question is will it work efficiently and scale to meet the needs of the business your agent placed you at. And that's a resounding no.
I've gone the other way (Oracle first, then SQL Server). My experience is:
SQL queries - trivial differences, except in the realm of string-date conversions, which are WAY easier in Oracle.
Stored Procedures - T-SQL syntax is significantly different from PL/SQL. There is a learning curve there, but nothing insurmountable.
Database Admin - very different, but WAY easier in SQL Server. If that's part of the job description, then they might be justified in considering someone else.
If you're being hired as a DBA, it will take a while to switch between databases as the management of them differs (I base this on my experience with Oracle and DB2 only).
I DON'T know SQL Server but I can imagine a Microsoft program with its nice GUI management would be vastly different to managing DB2/z, for example (although you can use the fancy DB2 LUW (Linux/UNIX/Window) tools if you're that way inclined).
If you're just cutting code to use the database, the SQL differences are minor (relatively). That shouldn't take much time at all, assuming you're already proficient with SQL.
I've done SQL Server for 10 years, but started working with Oracle about a year and a half ago. Like any database, there's no magical proficiency point - you just learn more about it the more you use it. In terms of what a developer would need to know, it shouldn't take more than a week (and even that's a bit much) for an experienced developer to get up to speed with using it. PL/SQL isn't that much different than T-SQL, although stored procs are kind of different.
Programming-wise, the Oracle data access classes are modeled on ADO.NET (we use OleDb actually - one of the side benefits is that you don't have to futz around with the OracleBlob class in order to access BLOB data), so not much learning to be done there.
I originally had my team using TOAD, because I had heard that TOAD is what you're supposed to use with Oracle (although I also heard bad things about it). We eventually got to the point where I was the only one using TOAD, and everyone else was using SqlDeveloper. Avoid TOAD.
I went from SQL Server to Oracle in 2001 where I went from working on a VB6/SQL Server project (as a developer) to working as an Oracle development DBA for a large J2EE project. Here are the edited highlights of my experiences and some reflections.
For development, the basic principle of SQL is not radically differnt. T-SQL is a somewhat different beast to PL/SQL so the idioms are a bit different. Most competent programmers should be able to make the jump by just tinkering around and getting some good SQL server books such as the Guru's Guide or Oracle books such as Expert one-on-one Oracle, depending on which way you're going.
I'd say for a developer a week or two to get used to another database platform will get you most of the way there. The basic principles are fairly similar (modulo differences in the architecture); really only the window dressing is different. However, if you're going to Oracle, get a copy of a third-party query tool such as TOAD as these are much, much, much better than the ones that Oracle supplies.
Agents are notoriously bad for matching specific buzzwords and I get this on a semi-regular basis (I'm a contractor). If you need to bone up on SQL Server the Developer Edition is very cheap and will install on a desktop O/S such as Windows XP. Oracle also offers Free downloads for all their supported platforms that you can use to tinker.
You might also get some mileage from asking a stackoverflow question along the lines of "What are the main idiomatic differences between PL/SQL and T-SQL".
If all you want to do is put a bullet point on your resume to get past the agents, just add it, that will get you past the agents and give you a chance to get your foot in the door. If you are an honest type, grab Oracle XE, Read the appropriate guide at the documentation library, and spend a day or 5 throwing together a blog/address book/flickr clone/etc in your favorite language against Oracle.
As others have suggested there is some significant difference in things you would do compared to SQL Server, if you just apply what you know from SQL Server to Oracle, you'll likely kill performance.
I would disagree that the SQL is similar. The SQL SYNTAX is similar (to the lowest common denominator of ANSI) for basic CRUD development. But actually building packages, writing multi-table / multi step joins, bulk updates and inserts, use of the rich and powerful Oracle feature set is very different from SQL Server. This takes a different mindset and can take many years to master. However...
The purpose of the CV / resume is to get an interview.
Work with your agent to highlight your best TALENTS and BEHAVIOUR'S, not purely skills.
Skill's can be learnt and taught. A talent for, and the demonstration of, learning new skills in new environments is gold dust for an employer.
Don't try to blag it. Don't lie. You'll be found out. Use your experience gained from SQL Server to demonstrate that you can solve the problem. Show eagerness to learn, train and graft.
But, if they really want a "parachute in and start running Oracle programmer", then your stuffed!
AS for my knowledge,It is better to learn Oracle rather than SQL Server because Through out my life I have come across majority of people who are working with SQL Server and a lot competition involved with it because this database is easy to learn.So If you learn oracle,it makes you strong at initial stages and less competition Involved with it.

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

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Closed 11 years ago.
MS SQL Server and Oracle, which one is better in terms of scalability?
For example, if the data size reach 500 TB etc.
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.
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.
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.
I've worked as a DBA on Oracle (although some years back) and I use MSSQL extensively now, although not as a formal DBA. My advice would be that in the vast majority of cases both will meet everything you can throw at them and your performance issues will be much more dependent upon database design and deployment than the underlying characteristics of the products, which in both cases are absolutely and utterly solid (MSSQL is the best product that MS makes in many peoples opinion so don't let the usual perception of MS blind you on that).
Myself I would tend towards MSSQL unless your system is going to be very large and truly enterprise level (massive numbers of users, multiple 9's uptime etc.) simply because in my experience Oracle tends to require a higher level of DBA knowledge and maintenance than MSSQL to get the best out of it. Oracle also tends to be more expensive, both for initial deployment and in the cost to hire DBAs for it. OTOH if you are looking at an enterprise system then Oracle would have the edge, not least because if you can afford it their support is second to none.
I have to agree with those who said deisgn was more important.
I've worked with superfast and super slow databases of many different flavors (the absolute worst being an Oracle database, but it wasn't Oracle's fault). Design of the database and how you decide to index it and partition it and query it have far more to do with the scalability than whether the product is from MSSQL Server or Oracle.
I think you may more easily find more Oracle dbas with terrabyte database experience (running a large database is a specialty just like knowing a particular flavor of SQL) but that could depend on your local area.
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
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.
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
I very much doubt that you are going to get an objective answer to that particular question, until you come across anyone that has implemented the same database (schema, data, etc.) on both platforms.
However given the fact that you can find millions of happy users of both databases, I dare say it's not too much of a stretch to say either will scale just fine (I've seen a snappy Sql 2005 implementation of 300 TB that seemed pretty responsive)
Oracle like a high-quality manual film camera, which needs the best photographer to take the best picture while MS SQL like an automatic digital camera. In old days, of course, all professional photographers will use film camera, now think about how many professional photographers use automatic digital camera.

Oracle XE or SQL Server Express

I'm starting a new project here (Windows Forms). What's the best option today for a small (free as in beer) DBMS?
I've used SQL Server Express on the past projects, but time and time again I hear people saying that the product from Oracle is faster and more powerful.
It will be used in a small company (around 20 users) and will not reach the 4 GB limit any time soon :)
I don't want to start a flame war on my first post, so please point me to some link showing a good (and actual) comparison between the 2 products, if possible.
PS: I've heard about IBM DB2 Express too, but I coudn't find any information about it. (Marketing material from IBM doesn't count :) )
I would go for the SQL Server Express solution, unless you absolutely have to use a feature in Oracle that SQL Server does not have and you have no usable workaround.
Example of Oracle's strengths:
Analytical Functions in Oracle ROCK!
PL/SQL is better than T-SQL.
If you're going to scale up the system to 1,000's of users all updating the same small dataset
You scale upto multi-TB databases,
You need to scale to need big numbers of CPU's in your server (over 8).
need instant failover (RAC)
you really cannot afford to lose a transaction.
Maybe you can tell, I'm a big Oracle fan! But I think that Oracle Express is a commercial reaction to SQL Server Express and I don't think Oracle really deep deep down likes it.
You know with SQL Server that there is an upgrade path (SQL Server 2008 is soon) plus service packs.
SQL Express is also more "install and forget" than Oracle.
and it will integrate better with your IDE (if your using .NET)
In terms of speed, both are going to be lighting quick with such a small dataset size.
It would be hard to argue either way given the needs you outlined, that either would shine over the other.
What I will say is this:
You say you are already familar with SSExpress, then that is a good reason to stick with it
IMHO the tools with SSExpress are superior and easier to use than the Oracle equivalent
That said, I have much more experience with SS than Oracle so YMMV.
Sorry, no link, but one advice. Because we support Oracle and SQL Server, I know that getting fixes for the 'normal' Oracle database, is not something what I call fun. You have to pay for it, and if you have no tool which updates your Oracle system for you, it's a pain in the a.., if you ask me. Check out how the Oracle XE is supported with updates/fixes. I don't know, I only use the 'normal' Oracle (Developer) database.
I think it's great to rethink things every once in a while and that it's very smart to consider alternative products when you are at a junction to do so.
If you are comfortable optimizing systems and are dba level in skills, I'd consider PostgreSQL. I do not consider myself a dba and have middling database skills and find SQL Server Express extremely easy to use. Also, I've had products exceed the limits of SQL Server Express - the transition to SQL Server Standard/Enterprise is seemless.
I realize that this doesn't matter at a technical level, but Larry Ellison buys jets and prostitutes with his profit. Bill Gates is solving problems of immense importance to humanity with his. All things being equal, I always prefer to give my money to Bill Gates.
Is this any use:
https://web.archive.org/web/1/http://downloads.techrepublic%2ecom%2ecom/5138-9592-6028761.html
NB Registration is required
Both of KiwiBastard's points are very good and I completely agree with him.
If you really want a free alternative that is similar to MS SQL and supports growth should you need it, you could have a look at MySQL or PostgreSQL. SQLite also seems a good choice.
Surely you can afford an old Linux server if you work in a company with 20 employees.
100% SQL Express, more easy to install and maintain than Oracle.
IMHO the major problem with SQL Server, has for a long time been, no multi-version read consistency. Fortunately this has been corrected since SQL Server 2005 with the snapshot isolation level.
If your looking for a good RDBMS for a small project requring minimal knowledge for maintenance, SQL Server Express Edition is a good pick. The SQL Server Express Edition UI is much easier to understand than RMAN or the "easier"-to-use backup scripts included with Oracle Database XE which requires offlining your database.
Oracle Database XE is on my *** list. They recently released an ODBC driver for Linux that wasn't compiled properly (ld returns missing symbols for required ODBC functions) to be at all usable (10.2.0.4). With this kind of lack of attention to any reasonable amount of QA even for a 'free' product I would think twice about going down that road.
For DB2 Express-C see:
"DB2 Express-C™ is the free version of one of the most advanced
database management systems in the world. Why pay when you can have
all you need for free? DB2 Express-C is free to develop, deploy and
distribute.
It is a fast, secure, reliable, and amazingly scalable dataserver,
ideal for most startups and small/medium sized businesses. DB2
Express-C 9.7 is available on Linux, Unix, Windows, and now Mac OS X
as well! It also enables developers to easily handle XML through the
native storage technology called pureXML™. Whether you develop in
Java, .Net, Ruby, Python, Perl or pretty much any other programming
language out there, DB2 can be your technological advantage."

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