I am writing some code that is importing a large amount of data into three tables currently around 6 million rows across the three tables. I am wanting to do this in a transaction so if there are any issues or the user cancels the import nothing is imported. This works fine on my own development machine however on a slower amazon ec2 instance and micro sql instance I am getting the following exception:
System.Data.SqlClient.SqlException: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding
Now I know that the commit is finishing eventually because the data is present in the tables when I look, so my question is; can this be easily avoided without adding the connection timeout property to my connection string (I only want this one operation to not timeout) or is this a really hard/dangerous thing to be doing?
I am not sure if maybe I should import into holding tables and then call stored procedures to move the data when I am ready because I would assume this will result in a shorter transaction)
I am using Ms Sql server 2012.
Do comment if I need to add more data.
Many thanks for your help
Check what is the SP getting timedout .. if you have any third party tool like Redgate or Avicode you can figure it out ..or use Profiler to figure it out.. then see the execution plan for the SP or query .. If you find any Key lookups or RID lookups then resolve it first and try again..
Related
I have a Hangfire service running on one of my servers, I'm a DBA and sometimes I'm asked to trigger jobs using the Dashboard, but it takes me a lot of time to connect to the jobs' server due to some connectivity and security issues.
And to overcome that, I want to trigger those jobs by inserting in Hangfire's tables on the database, I can already query those tables to find which job executed when and whether they failed, succeeded or still enqueued, does anyone know an approach to do so?
I've included a sample of two tables which I think will be used to do this trick, their names are Hash and Set respectively:
Hangfire normally uses a gui like swagger in .net (http://localhost:5000/hangfire) , there should be a immediate trigger feature. If not a second option is changing the cron expression for every minute or maybe every 30 seconds.
I have a SQL Server agent job running every 5 minutes with SSIS package from SSIS Catalog, that package does:
DELETE all existing data ON OLTP_DB
Extract data from Production DB
DELETE all existing data on OLAP_DB and then
Extract data transformed from OLTP_DB into OLAP_DB ...
PROBLEM
That job I mentioned above is hanging randomly for some reason that I don't know,
I just realize using the activity monitor, every time it hangs it shows something like:
and if I try to run any query against that database it does not response just say executing.... and nothing happen until I stop the job.
The average running time for that job is 5 or 6 minutes, but when it hangs it can stay running for days if I don´t stop it. :(
WHAT I HAVE DONE
Set delayValidation : True
Improved my queries
No transactions running
No locking or blocking (I guess)
Rebuild and organize index
Ran DBCC FREEPROCCACHE
Ran DBCC FREESESSIONCACHE
ETC.....
My settings:
Recovery Mode Simple
SSIS OLE DB Destination
1-Keep Identity (checked)
2-Keep Nulls (checked)
3-Table lock (checked)
4-Check constraints (unchecked)
rows per batch (blank)
Maximum insert commit size(2147483647)
Note:
I have another job running a ssis package as well (small) in the same instance but different databases and when the main ETL mentioned above hangs then this small one sometimes, that is why I think the problem is with the instance (I guess).
I'm open to provide more information as need it.
Any assistance or help would be really appreciated!
As Joeren Mostert said, it's showing CXPACKET which means that it's executing some work in parallel. (cxpacket)
It's also showing ASYNC_NETWORK_IO (async_network_io) which means it's also transfering data to the network.
There could be many reasons. Just a few more hints:
- Have you checked if network connection is slow? - What is the size of the data being transfered vs the speed of the network? - Is there an antivirus running that could slow the data transfer?
My guess is that there is lots of data to transfer and that it's taking a long time. I would think either I/O or network but since you have an asyn_network_io that takes most of the cumulative wait time, I would go for network.
As #Jeroen Mostert and #Danielle Paquette-Harvey Said, By doing right click using the activity monitor I could figure out that I had an object that was executing in parallel (for some reason in the past), to fix the problem I remove the parallel structure and put everything to run in one batch.
Now it is working like a charm!!
Before:
After:
We are having multi server and multi DB instances in EC2. In one of the Server we have the Main DB(Master DB), but in other servers we have only the Transaction DB's. We are using SQL linked server to connect everything.
Initially there was no problem with my infrastructure. But now as the data load increased, am often getting Time Out expired error even for an normal select query.
Its not for all the processes. If there are 500 processes running in a particular server, in that at-least 200 processes are throwing this Time out expired error.
Recently, I moved all my servers into VPC.
Note:
All my queries will be running only from Master DB because only master DB knows what transaction DB is connected to respective transaction requests. All EC2 instances are in the same region.
Is there a solution for my problem ( time out error exception ). Kindly help me with your suggestions. This is really turning out into an critical business affecting issue.
Error Msg:
Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.
Since it worked fine before and started to fail with as load increased, sounds like you are running out or resources (mostly hardware). There are two things to do:
1) Buy more hardware;
2) Tunning your queries to do more work with less (hardware).
The first thing is (maybe) cheaper. To tuning your DB it ill take a lot of time for learning and test out whatever you learn.
I suggest you to get the hard way and try to optimize your queries/isolation level/schema etc.
I have a reporting solution with several reports. Up to now, I have been able to add a dataset based on a SPROC with no problems. However, when I try to add the lastest dataset, and use a SPROC for its query type, when I click on Refresh Fields I get the following error:
Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.
I have tested the database connection in Data Source properties>Edit>Test Connection, and it's working fine.
I have increased the timeout to 100 in the following areas:
The connection string for the datasource, which is - Connect
Timeout=100
Tools>Options>Database Tools>Query and View
Designers. Cancel long running query is set to 100.
Tools>Options>Database Tools>Table and Database Designers>Checked
'Override Connection String time-out value for table designer
updates. Transaction time-out after is set to 100
The SPROC runs fine in the SQL database. It takes about 55 seconds.
Any other ideas?
Thanks.
UPDATE: I now can't add any dataset with a SPROC. Even thought the SPROCs are all working fine in SQL!!!!!!
If you are using Report Builder, you can increase timeout also in your DataSet.
I have also face same problem for adding the newly added column in stored procedure.
From the following way overcome this issue.
Alter the stored procedure as comment all the query except that final select command.
Now that new column has been added, then un-comment that quires in sp.
The thing to remember with your report is that when it is ran, it will attempt to run ALL the datasets just to make sure the are runnable, and the data they are requesting can be returned. So by running the each proc seperately you are in fact not duplicating with SSRS is trying to do...and to be honest don't bother.
What you could try is running sp_who while the report is running, or even just manually go through the procedures to see what table they have in common. Since your proc takes 52 seconds to return its dataset I'm going to assume its doing some heavy lifting. Without the queries nobody will be able to tell what the exact problem is.
I suggest using NO LOCK to see if that resolves your issue. If it does then your procs are fighting for data and blocking each other...possibly in a endless loop. Using NO LOCK is NOT a fix. Read what it does and judge for yourself however.
My solution was to go to the Dataset Properties for the given problem dataset, paste the query in the Query field, click Refresh Fields, and click Ok.
I've got a scenario when sometimes a user selects the right parameters and makes a query which takes several minutes or more to execute. I cannot prevent him to select such a combination of parameters (it's quite legal), so I'd like to set a timeout on the query.
Note that I really want to stop the query execution itself and rollback any transactions, because otherwise it hogs up most of server resources. Add an impatient user who restarts the application and tries the combination again, and you've got a recipe for a disaster (read: SQL Server DoS).
Can this be done and how?
As far as I know, apart from setting the command or connection timeouts in the client, there is no way to change timeouts on a query by query basis in the server.
You can indeed change the default 600 seconds using sp_configure, but these are server scoped.
Humm!
did you try LOCK_TIMEOUT
Note down what it was orginally before running the query
set it for your query
after running your query set it back to original value
SET LOCK_TIMEOUT 1800;
SELECT ##LOCK_TIMEOUT AS [Lock Timeout];
I might suggest 2 things.
1)
If your query takes a lot of time because it´s using several tables that might involve locks, a quite fast solution is to run your queries with the "NoLock" hint.
Simply add Select * from YourTable WITH (NOLOCK) in all your table references an that will prevent your query to block for concurrent transactions.
2) if you want to be sure that all of your queries runs in (let´s say) less than 5 seconds, then you could add what #talha proposed, that worked sweet for me
Just add at the top of your execution
SET LOCK_TIMEOUT 5000; --5 seconds.
And that will cause that your query takes less than 5 or fail. Then you should catch the exception and rollback if needed.
Hope it helps.
In management studio you can set the timeout in seconds.
menu Tools => Options set the field and then Ok
It sounds like more of an architectual issue, and any timeout/disconnect you can do would be more or less a band-aid. This has to be solved on SQL server side, by the way of read-only replica, transaction log shipping (to give you a read-only server to connect to), replication and such. Basically you give the DMZ sql server that heavy read can go to without killing stuff. This is very common. A well-designed SQL system won't be taken down by DDoS - that'd be like a car that dies if you step on the gas.
That said, if you are at the liberty to change the code, you could guesstimate if the query is too heavy and you could either reject or return only X rows in your stored procedure. If you are mated to some reporting tool and such and can't control the SELECT it generates, you could point it to a view and then do the safety valve in the view.
Also, if up-to-the-minute freshness isn't critical and you could compromise on that, like monthly sales data, then compiling a physical table of complex joins by job to avoid complex joins might do the trick - that way everything would be sub-second per query.
It entirely depends on what you are doing, but there is always a solution. Sometimes it takes extra coding to optimize it, sometimes it takes extra money to get you the secondary read-only DB, sometimes it needs time and attention in index tuning.
So it entirely depends, but I'd start with "what can I compromise? what can I change?" and go from there.
You can set Execution time-out in seconds.
If you have just one query I don't know how to set timeout on T-SQL level.
However if you have a few queries (i.e. collecting data into temporary tables) inside stored procedure you can just control time of execution with GETDATE(), DATEDIFF() and a few INT variables storing time of execution of each part.
You can specify the connection timeout within the SQL connection string, when you connect to the database, like so:
"Data Source=localhost;Initial Catalog=database;Connect Timeout=15"
On the server level, use MSSQLMS to view the server properties, and on the Connections page you can specify the default query timeout.
I'm not quite sure that queries keep on running after the client connection has closed. Queries should not take that long either, MSSQL can handle large databases, I've worked with GB's of data on it before. Run a performance profile on the queries, prehaps some well-placed indexes could speed it up, or rewriting the query could too.
Update:
According to this list, SQL timeouts happen when waiting for attention acknowledgement from server:
Suppose you execute a command, then the command times out. When this happens the SqlClient driver sends a special 8 byte packet to the server called an attention packet. This tells the server to stop executing the current command. When we send the attention packet, we have to wait for the attention acknowledgement from the server and this can in theory take a long time and time out. You can also send this packet by calling SqlCommand.Cancel on an asynchronous SqlCommand object. This one is a special case where we use a 5 second timeout. In most cases you will never hit this one, the server is usually very responsive to attention packets because these are handled very low in the network layer.
So it seems that after the client connection times out, a signal is sent to the server to cancel the running query too.