Looks like somebody is really trying to hack into your SQL Server with brute force attacks. I recommend taking a look at this Whitepaper on SQL Server security, that will help you a lot. Since most attacks happen at the same time, make sure you don't have a security scanner on your network that runs its checks at that time. Locking is essential to successful SQL Server transactions processing and it is designed to allow SQL Server to work seamlessly in a multi-user environment. Locking is the way that SQL Server manages transaction concurrency. Essentially, locks are in-memory structures which have owners, types, and the hash of the resource that it should protect. Locking is essential to successful SQL Server transactions processing and it is designed to allow SQL Server to work seamlessly in a multi-user environment. Locking is the way that SQL Server manages transaction concurrency. Essentially, locks are in-memory structures which have owners, types, and the hash of the resource that it should protect. Here are nine hacker tricks used to gain access and abuse systems running Microsoft SQL Server. Direct connections via the Internet. These connections can be used to attach to SQL Servers sitting naked without firewall protection for the entire world to see (and access). How to avoid attacks on Web server; Hacking Activity: Hack a WebServer; Web server vulnerabilities. A web server is a program that stores files (usually web pages) and makes them accessible via the network or the internet. A web server requires both hardware and software.
Active4 years, 2 months ago
This was my original question:
I am trying to figure out how to enforce EXCLUSIVE table locks in SQL Server. I need to work around uncooperative readers (beyond my control, closed source stuff) which explicitly set their ISOLATION LEVEL to READ UNCOMMITTED. The effect is that no matter how many locks and what kind of isolation I specify while doing an insert/update, a client just needs to set the right isolation and is back to reading my garbage-in-progress.
The answer turned out to be quite simple - Tony hawk pro skater 3 iso pc.
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while there is no way to trigger an explicit lock, any DDL change triggers the lock I was looking for.
While this situation is not ideal (the client blocks instead of witnessing repeatable reads), it is much better than letting the client override the isolation and reading dirty data. Here is the full example code with the dummy-trigger lock mechanism
WINNING!
RESULT:emlai
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Peter RabbitsonPeter Rabbitson
3 Answers
One hack hack hack way to do this is to force an operation on the table which takes a SCH-M lock on the table, which will prevent reads against the table even in READ UNCOMMITTED isolation level. Eg, doing an operation like ALTER TABLE REBUILD (perhaps on a specific empty partition to reduce performance impact) as part of your operation will prevent all concurrent access to the table until you commit.
stevehemstevehem
Add a locking hint to your
SELECT :
SELECT COUNT(*) FROM artist WITH (TABLOCKX)
and put your
INSERT into a transaction.
If your initial statement is in an explicit transaction, the JNKJNK
SELECT will wait for a lock before it processes.
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There's no direct way to force locking when a connection is in the
READ UNCOMMITTED isolation level.
A solution would be to create views over the tables being read that supply the
READCOMMITTED table hint. If you control the table names used by the reader, this could be pretty straightforward. Otherwise, you'll have quite a chore as you'll have to either modify writers to write to new tables or create INSTEAD OF INSERT/UPDATE triggers on the views.
Edit:
Michael Fredrickson is correct in pointing out that a view simply defined as a select from a base table with a table hint wouldn't require any trigger definitions to be updatable. If you were to rename the existing problematic tables and replace them with views, the third-party client ought to be none the wiser.
zinglonzinglon
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Active9 years, 3 months ago
My company is working on a development project using SQL Server 2008 Express. The amount of data we plan to store in our main table will quickly exceed the 4GB size limit of Express. We can buy ourselves some time with SQL Server 2008 R2, but eventually we will surpass the 10GB limitation as well.
The team lead wants to hear all available options before purchasing licenses for Standard Edition. The expertise available in our company is SQL Server and Oracle, so using MySQL or PostgresSQL would be considered a last resort.
The only alternative I can think of is a design where the main table is horizontally partitioned into separate, distinct databases. In addition, there would be a central database to store the information about where the data was stored.
For example, all of the table data for 2008 would be stored in DB_2008, 2009 data in DB_2009, and so on. The metadata table might look like this:
Sql Server Management Studio
This table would be used to determine the database location of the data for our stored procedures. Most of our code already uses parameterized, dynamic SQL, so this would not be difficult to implement.
Has anyone ever done this before?
Is there an established model for this type of design or is it just a horrible idea?
8kb8kb
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6 Answers
I realize this doesn't address your question exactly, but in my experience it's always more expensive to hack up a nasty kludge like this--think dollars per hour for development and maintenance, plus the time you've lost developing features that really matter--than to buy the right tools in the first place.
EDITED: And why Standard edition instead of Workgroup? If Express satisfies your feature requirements, so will Workgroup, and it's ~$3500 cheaper than Standard. Still, either is a bargain compared to saddling yourself as described above -- doubly so if you can license by CAL instead of by Processor. :-)
Ben MBen M
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It's a horrible idea. IANAL, but you may still be violating the SQL Server license even with this scheme. They put in all sorts of fine print about 'multiplexing' and whatnot.
Even if you got this to work, you could very well run into nasty performance and authentication issues, and maintaining the data would be a pain. Assuming your developers don't work for free, buying a license would be cheaper.
Don't do it.
Dave MarkleDave Markle
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The only way I would consider doing anything like this is if I was guaranteed that
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The reality is that those constraints rarely work. Consider someone wanting a 12 month report in march, from the previous march.. You'll have to aggregate the results in code.
At the end of the day you are going to spend a LOT more in development time making this work than a sql standard license will cost you. EDIT: I take that last sentence back: it will cost more to do than a sql enterprise license would.
NotMeNotMe
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There is no such thing as free software! :) Even if you can get around the 10GB size limitation you will still be limited by the 1GB memory ceiling. With a 10GB database that will most likely seriously impair performance (unless your query workload is very small).
Note that if you have varbinary data in your database you can store that outside of the 10GB limit by using Filestream.
nvogelnvogel
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It can be done, you see it in data warehousing and document storage, but those are systems where you rarely need to select accross a boundary (year, etc). If you will often need to work with data from multiple partitions/databases it's probably cheaper to buy the license than do the coding and support of the partitioned model.
C. RossC. Ross
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Have you seen the Web Edition of SQL Server? If you fit into it's licensing model, it does all of the main sql server stuff (doesn't do mirroring and can't server as a replication source, among some other limitations) but is very affordable.
Sql Server ExpressRQDQRQDQ
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