There are some features in our LOB application that allow users to define their own queries to retrieve data for reports and listings within the app. The problem that we are encountering is that sometimes these queries they have written a really heavy (and sometimes erroneous) and cause massive load on the server.
Removing these features is out of the question but Im wanting to know if there is a way to create some type of sandbox within SQL server so that the queries that they execute are only allotted a certain amount of resources to execute therefore not giving them the chance to cause any damage to anyone else using the system. Any ideas?
The Resource governor has been mentioned in the comments above already. One other solution I can think of is using SQL Server High Availability Groups.
At the last place I worked had this kind of set up. There is a primary server which takes in all the transactions that write stuff to the database, with a secondary in case the primary fails. Added to this we also had read-only replicas added to the availability group.
The main purpose of this is in the event that your main server goes down you are automatically transferred to another replica. When you connect your application to the database, you connect it to the Availability Group rather than a specific server. Then if a server goes down you are automatically transferred to a secondary server instead. However, it can also be used to optimise application functionality that just needs read-only access by taking load off the primary server.
Any functionality that we knew that it only needed read-only access then we could connect to the availability group and add into the connection string ApplicationIntent=READONLY which means that we're using the read-only replica rather than the primary, leaving the primary for regular transactions. (IIRC, by default the primary will accept any read/write connection, so you have to configure the primary not to accept read-only connections)
Anyway, the kicking off point for reading up about this is here: https://msdn.microsoft.com/en-us/library/ms190202.aspx
The latest Windows 10 1903 upgrade already has inbuilt Sandbox features, where you can run SQL server within it's own sandbox. I don't think SQL Server itself has its own inbuilt sandbox environment, as it would be practically impossible to manage within a normal Windows server that is not using sandbox, if you know what I mean.
Related
I have set up an Azure database instance which supposedly replicates into a 'read only' secondary database using standard geo-replication. In the Azure portal I can see the status of the replication is 'online' and 'Secondary type' is 'Offline', which appears to be normal.
My question is, is there a way for me to see the actual contents of the secondary database, to ensure the replication is actually working as planned?
I cannot 'Manage' the database in the portal. I can connect to the instance in SQL Management Studio, where I can see the database but expanding tables / stored procedures shows nothing (a bit like connecting to a secure database using the non-secure connection string). I am also not able to run any queries against it as it gives me 'Connection to an offline secondary database is not allowed.'
I've searched this site an did a web search for an answer but can't seem to find one. Am I supposed to blindly rely on the fact that Azure is perfoming the replication correctly (with no way to double-check), or am I missing something here?
Many thanks in advance for any light you are able to shed on this.
Standard Geo-Replicated Secondary DBs are offline copies that do not accept client connections (so there is no way to query the data directly). If you need a readable Geo-Replicated Secondary then you must use the Active Geo-Replication available for Premium DBs.
Even though you can't query Standard Geo-Replicated DBs directly, you can use the DMVs in the Master to determine if the continuous copy is working correctly.
On the Master try the following:
SELECT * FROM sys.dm_database_copies
SELECT * FROM sys.dm_Continuous_copy_status
I hope this helps!
For more information about Standard Geo-Replication, Active Geo-Replication Or Checking the activity of continuous copy use the following links.
Standard Geo-Replication: https://msdn.microsoft.com/en-us/library/azure/Dn758204.aspx
Active Geo-Replication: https://msdn.microsoft.com/en-us/library/azure/dn741339.aspx
Continuous Copy DMV Blog: http://www.sqlservercentral.com/blogs/pie-in-the-sky/2014/12/25/monitoring-geo-replication-in-sql-azure-using-dmvs/
I tried to repro your situation and I think I understand the confusion.
When the Secondary Type = "Offline" then it is a standard Geo-Replicated Secondary. The Primary Databases page is confusing, but when you click on the link to the secondary should show that it is offline.
As far as understanding if the continuous copy is working, run the script below against the Primary (I was mistaken last time, Sorry).
SELECT * FROM sys.dm_Continuous_copy_status
You should see the linked server, database, and Replication State.
As before if you need to read from your secondary, you will have to created a premium active-Geo Replicated Secondary.
Hope This helps!
I have a delicate situation wherein some records in my database are inexplicably missing. Each record has a sequential number, and the number sequence skips over entire blocks. My server program also keeps a log file of all the transactions received and posted to the database, and those missing records do appear in the log, but not in the database. The gaps of missing records coincide precisely with the dates and times of the records that show in the log.
The project, still currently under development, consists of a server program (written by me in Visual Basic 2010) running on a development computer in my office. The system retrieves data from our field personnel via their iPhones (running a specialized app also developed by me). The database is located on another server in our server room.
No one but me has access to my development server, which holds the log files, but there is one other person who has full access to the server that hosts the database: our head IT guy, who has complained that he believes he should have been the developer on this project.
It's very difficult for me to believe he would sabotage my data, but so far there is no other explanation that I can see.
Anyway, enough of my whining. What I need to know is, is there a way to determine who has done what to my database?
If you are using identity for your "sequential number", and your insert statement errors out the identity value will still be incremented even though no record has been inserted. Just another possible cause for this issue outside of "tampering".
Look at the transaction log if it hasn't been truncated yet:
How to view transaction logs in SQL Server 2008
How do I view the transaction log in SQL Server 2008?
If you want to catch the changes in real time, I suggest you consider using SqlDependency. This way, when data changes, you will be alerted immediately and can check which user is using the database at the very moment (this could also be done using code).
You can use this code sample.
Coming to think about it, you can establish the same effect using a trigger and writing ti a table active users. Of course, if you are suspecting someone is tempering with data, using SqlDependency might be a better way to go with, as the data will be stored outside of the tampered database.
You can run a trace, for example a distant profiler trace, that will get all SQL queries containing the DELETE keyword. This way, nobody will be aware that queries are traced. You can also query the default trace regularly to get the last DELETE commands: Maintaining SQL Server default trace historical events for analysis and reporting
Please advise what suits my problem better. I have a highload web app hosted on the same server where SQL server is hosted. I also have SQL Service reporting running on the same server, generating user reports.
So my server basically works on top of disk read/write speed. I'm going to get another server and install there another SQL server in order to host SSRS there. So my criteria is to get as fresh data as it possible.
I've looked a couple of solution, currently I do make backup via jobs, copy it to second server and restore it there, also via jobs. But that's not the best solution.
All replication mechanism(transaction, merge, snapshot) affect publisher database by locking it's table, what is unacceptable for me.
So I wonder is there any possibility to create a replica with read only access, that would be synced periodically not affecting main db? I would put all report load to that replica and make my primary db be used only by web app.
What solution might suit my problem? As I'm not a DBA, I'd start investigating that direction. Thanks.
Transactional Replication is typically used to off-load reporting to another server/instance and can be near real-time in a best case scenario. The benefit of Transactional Replication is you can place different indexes on the subscriber(s) to optimize reporting. You can also choose to replicate only a portion of the data if only a subset is needed for reporting.
The only time locking occurs with Transactional Replication is when you generate a snapshot. With concurrent snapshot processing, which is the default for Transactional Replication, the shared locks are only held for a short period of time, so users are able to continue working uninterrupted. Either way, this shouldn't be an issue since you'll likely be generating the snapshot during a period of low user activity anyway.
My requirement is to retrieve data from a local SQL server and store that data in remote server. I would like to get the data from the local SQL Server and use that data in my application to proceed further.
Yes, see Create linked server with SQL command.
You can create the linked server either locally (I'd recommend that) or remotely
If you mean you want your remote server to execute queries on the local one then yes, but...
Setting this up is a fair bit of work and if I remember rightly needs a hefty amount of privileges on the remote server.
Might be easier to set up the linked server locally. NB assumes the account the local server is running as can reach the remote machine, and can access it.
I'd be a bit nervous about doing this, internally for fear of some admin type breaking it, if it's over the internet, then securing it will be a nightmare even if they allowed their server to be accessed directly..
You might find it easier to do it via the client, though that will dpend on how much data you want to synchronise, and then perhaps a briefcase approach might do the job better.
You can set up linked servers either via the GUI in SSMS, or via scripts. A couple of things to look out for though - first make sure you create a login account on each server that is mapped to the appropriate database on each server, with the least possible permissions. Then verify the mapping after you've set it up. Be aware that you are opening up the attack surface via this solution, so you may want to have your admin set up auditing too.
I am working on a project which uses a relational database (SQL Server 2008). The local (on-premises) application both reads and writes to the database. I am working on a different front end for Azure (MVC2 Web Role), which will use the same data, but in a read only fashion. If I was deploying a traditional web app, I would use SQL Express to act as the local database, and deploy changes with updates to the application (the data changes very slowly) or via some sync system.
With Azure, the picture is a little cloudy (sorry, I had to). I can't seem to find any information to indicate if SQL Express will work inside of Web Roles, and if so, how to do it. Does anyone know if using SQL Express in an Azure web role is possible?
Other options I could do if forced: SQL CE or use SQL Azure. Both have a number of downsides, and are definitely less than perfect.
Thanks,
Erick
Edit
I think my scenario may not have been clear enough.
This data won't change between deployments, and is only accessed from within the Web Role; it is basically a static cache. The on-premises part is kind of a red herring, as it doesn't impact the data on the web role (aside from being its source). Basically, what I want to do is have a local data store/cache that I use existing T-SQL/DAL code with.
While I could use SQL Azure, it doesn't add anything, and if anything only adds additional overhead and failure points. I could also use a VM Role, but that is way too costly/complex.
In a perfect world, I would package the MDF into the cspkg (so it gets deployed with the app) and then use it locally from within the role. If there is no way to do this, then that is ok and I need to figure out the pros and cons of other solutions. We don't live in a perfect world. :)
You might be able to run SQL Express using a custom VHD but you won't be able to rely on any data every being present on that VHD. The VMs are completely reset when they reboot - there is no physical persistence across reboots.
If you wanted to, you might be able to locate your entire SQL Server installation in Azure blob storage.
However, in doing all of this, you'll only be able to have one worker/web role that can use that database. Remember: a SQL Server database can only be attached to one SQL Server at a time. If you want to scale out, you'll have to create new SQL Server instances for every web/worker role.
Outside of cost concerns, I can't think of anything that is in SQL Express that should be a show stopper for 99.9% of applications out there.
Adding to Jeremiah's answer: SQL Azure should give you nearly everything SQL Express does today, and you can use the Sync service to synchronize on-premise SQL Server with SQL Azure.
If you installed SQL Express into a VM role, you'd be consuming around $90 monthly just for that instance, plus blob storage (you'd want a Cloud Drive for durability). By definition, a VM Role (or any role) must support scale-out; if you were to scale to 2 instances for whatever reason, both instances would need their own copy of the database, so you'd need to create a blob snapshot for each instance.
Keep in mind, though, if you choose to install SQL Express in a VM: once you're at 2 instances, along with, say, 20GB per instance of blob storage, you're nearing $200 monthly and you're maintaining your VM's OS patches, SQL Express configuration and updates, failure recovery procedures, etc. In contrast, SQL Azure at 20GB, while costing the same $200, will offer better performance and works with the sync service, while completely removing any OS or database server management tasks from you.
To add to the already existing answers and for anyone wondering if its a good idea to run SQL Express in the cloud:
it does makes sense as a temporary storage area. Consider this architectural approach:
say you're spinning up nodes to run jobs. Storing a gazillion of calculation results might be a good idea inside a local SQL Express for each node, and provide the aggregated responses immediately when the job finishes on the node. Transfer of the no longer hot results to off-prem SQL server for future reporting/etc can be done afterwords. SQL Azure may not be optimal from the volume/latency/cost perspective to store gazillion of results and ATS will not always fit the bill, especially when relational data, performance or existing code are involved.
To expand on what David mentioned you can register for SQL Azure Data Sync CTP2 that would allow sync from SQL Server to SQL Azure here: http://www.microsoft.com/en-us/SQLAzure/datasync.aspx
Make sure to use CTP2 though since CTP1 did not support SQL Server.
If it's a read only local cache - SQL CE 4 or SQLite.
Both have Entity Framework providers.
If you're writing to it - SQL Azure