I use RODBC to send queries to an SQL-Server. Sometimes they take too much time to run, so I need to cancel them.
Clicking the red "stop" button in RStudio yields this error message:
R is not responding to your request to interrupt processing so to stop
the current operation you may need to terminate R entirely.
Terminating R will cause your R session to immediately abort. Active
computations will be interrupted and unsaved source file changes and
workspace objects will be discarded.
Do you want to terminate R now?
And if I click yes my session is indeed terminated. (note: using Rgui instead of RStudio doesn't make things better)
However:
when I use another software (named "Query ExPlus") to connect to this same SQL-Server, I have a similar stop button, and clicking it instantly interrupts the query, without any crash.
when I connect to a PostgreSQL database using the RPostgres package I can also interrupt the query at any time.
These two points lead me to think that there should be a way to solve my problem. What can I do?
So far my workaround is:
library(RODBC)
library(R.utils)
withTimeout(mydf <- sqlQuery(myconnection, myquery), timeout=120)
Note: I don't have permission to kill queries from the database side.
I've just stumbled upon the odbc package. It allows to interrupt a query at any time.
Basic usage goes like this:
library(DBI)
myconnection <- dbConnect(odbc::odbc(),
driver = "SQL Server",
server = "my_server_IP_address",
database = "my_DB_name",
uid = "my_user_id",
pwd = "my_password")
dbGetQuery(myconnection, myquery)
I don't have a deep understanding of what happens behind the scenes, but for what I've seen so far in my personal use this package has other advantages over RODBC:
really faster
get the column types from the DB instead of guessing them (see here)
no stringsAsFactors and as.is arguments necessary
Most SQL Server users use SQL Server Management Studio (which is free and can be downloaded from Microsoft) to connect to SQL Server or execute commands from the command line via a tool called SQLCMD.
If you can determine the session id that the SQL Command is being run in you can kill the session which would stop any executing command(s). SQL Server will still need time (could be a 'long' time) to rollback any changes made during the execution of the command.
Terminating a session (depending on the software) can take a while to communicate to SQL Server that the session has been terminated. When I connected to DB2 from SQL Server using linked servers DB2 would buffer the terminate command and it would frequently take up to an hour for DB2 to realize the session had been terminated.
To determine what the session you are running in you can try:
select ##spid;
once you have the spid (lets say 86)
you can then issue (depending on if you have permission to do so)
kill 86;
but as Microsoft notes:
Terminates a user process that is based on the session ID or unit of work (UOW). If the specified session ID or UOW has a lot of work to undo, the KILL statement may take some time to complete, particularly when it involves rolling back a long transaction.
Try to close your "tab query" on SQL Server Management Studio
Then it will appear pop-up,
This Query is currently executing. Do you want to cancel this query ?
Cancel anyway, choose "yes".
try to set your connection prior to query:
sql = odbcConnect('Database name')
Then use same line to run your query:
mydf <- sqlQuery(sql, " myquery ")
Note: The running time is dependant on both database and R server but setting up the connection this way should resolve termination problem.
I am doing restores across servers via dynamic sql and linked servers as follows:
Exec ('USE MASTER; RESTORE DATABASE <dbname> FROM DISK = <path> WITH REPLACE, RECOVERY') AT <target server>
The database is set to single user mode before the above statement runs. However, on intermittent occasions, when trying to get the database back to multi user mode I get the a query timeout from the the target server and error:
ALTER DATABASE is not permitted while a database is in the Restoring state
I have looked around for this error but apparently I'm should not be getting it when using the RECOVERY option.
Any ideas please?
I managed to figure this out today. The culprit behind the issue was the default remote query time out for Sql Server which is 600s (10mins). More on this in the following link https://msdn.microsoft.com/en-us/library/ms189040(v=sql.105).aspx
My restore usually takes around 10mins to complete, sometimes a bit less so it succeeds and sometimes a bit more when it fails. Hence the issue was manifesting itself intermittently.
I increased the remote query time out on the source server to 36000s and it restored successfully. Just to prove the point, I decreased the remote query time out to a small figure like 60s and got the same symptom again.
Michelle - I set the database in single user to kill any running queries before the restore and to make sure there are no conflicts whilst the database is restored. This would eliminate the Exclusive Access could not be obtained because the database is in use error. Alternatively the database can be put to offline before the restore is initiated and back to online afterwards.
We are building an ERP system, and sometimes we need to see the SQL statement in SQL Server Profiler for debuging purposes. I can catch my ERP's queries by the SPID on Profiler. My ERP doesnt keep an open connection, it opens a connection everytime it needs it.
I have been thinking that everytime my ERP opens a connection, it should get a new SPID. How does it give the same SPID?
SPIDs are recycled, they are guaranteed to be unique at any one time, but if a connection drops, its SPID can be reused by a new connection.
My application is periodically connecting to MyDatabase and performing a query.
I need to handle the case where the MyDatabase database does not already exist and needs to be created. What I am doing currently is each time I first connect to the master database and run something like this:
SELECT * FROM sysdatabases WHERE NAME='MyDatabase'
to determine whether MyDatabase exists. If it doesn't I create it and then proceed with connecting to MyDatabase and performing the query.
Opening a separate connection to the master database and performing a query each time seems unnecessary (even though the connections are pooled). Why can't I just connect to MyDatabase straight away? 99% of the time it will succeed and I can execute the queries. The 1% of times it fails I can detect MyDatabase is missing and create it at that point right?
But when I try this I hit a problem. If I attempt to connect to MyDatabase and it doesn't exist I get a SqlException
Cannot open database MyDatabase requested by the login. The login failed.
Fine. Great. I can catch any SqlException and then go off to the master database to determine MyDatabase does not exist and create it.
But after creating it, when I now try to connect to MyDatabase I immediately get the same error:
Cannot open database MyDatabase requested by the login. The login failed.
It looks like it isn't trying to connect again and instead is returning a cached result. If I wait 10 seconds after creating the database before attempting to connect to it, the connection succeeds.
My question is, is this caching expected (I guess so) and more importantly is there a best practice for dealing with this situation? Is there perhaps a cache clearance or timeout setting in the SqlConnection API I can use? I could implement my own timeout delay I think but I would like to know there isn't a better method I am missing.
I had exactly the same problem.
When I call the static SqlConnection.ClearAllPools() method before I try to open the newly created database, it works fine!
I'm trying to perform some offline maintenance (dev database restore from live backup) on my dev database, but the 'Take Offline' command via SQL Server Management Studio is performing extremely slowly - on the order of 30 minutes plus now. I am just about at my wits end and I can't seem to find any references online as to what might be causing the speed problem, or how to fix it.
Some sites have suggested that open connections to the database cause this slowdown, but the only application that uses this database is my dev machine's IIS instance, and the service is stopped - there are no more open connections.
What could be causing this slowdown, and what can I do to speed it up?
After some additional searching (new search terms inspired by gbn's answer and u07ch's comment on KMike's answer) I found this, which completed successfully in 2 seconds:
ALTER DATABASE <dbname> SET OFFLINE WITH ROLLBACK IMMEDIATE
(Update)
When this still fails with the following error, you can fix it as inspired by this blog post:
ALTER DATABASE failed because a lock could not be placed on database 'dbname' Try again later.
you can run the following command to find out who is keeping a lock on your database:
EXEC sp_who2
And use whatever SPID you find in the following command:
KILL <SPID>
Then run the ALTER DATABASE command again. It should now work.
There is most likely a connection to the DB from somewhere (a rare example: asynchronous statistic update)
To find connections, use sys.sysprocesses
USE master
SELECT * FROM sys.sysprocesses WHERE dbid = DB_ID('MyDB')
To force disconnections, use ROLLBACK IMMEDIATE
USE master
ALTER DATABASE MyDB SET SINGLE_USER WITH ROLLBACK IMMEDIATE
Do you have any open SQL Server Management Studio windows that are connected to this DB?
Put it in single user mode, and then try again.
In my case, after waiting so much for it to finish I had no patience and simply closed management studio. Before exiting, it showed the success message, db is offline. The files were available to rename.
execute the stored procedure
sp_who2
This will allow you to see if there is any blocking locks.. kill their should fix it.
In SSMS: right-click on SQL server icon, Activity Monitor. Open Processes. Find the processed connected. Right-click on the process, Kill.
In my case I had looked at some tables in the DB prior to executing this action. My user account was holding an active connection to this DB in SSMS. Once I disconnected from the server in SSMS (leaving the 'Take database offline' dialog box open) the operation succeeded.
anytime you run into this type of thing you should always think of your transaction log. The alter db statment with rollback immediate indicates this to be the case. Check this out: http://msdn.microsoft.com/en-us/library/ms189085.aspx
Bone up on checkpoints, etc. You need to decide if the transactions in your log are worth saving or not and then pick the mode to run your db in accordingly. There's really no reason for you to have to wait but also no reason for you to lose data either - you can have both.
Closing the instance of SSMS (SQL Service Manager) from which the request was made solved the problem for me.....
To get around this I stopped the website that was connected to the db in IIS and immediately the 'frozen' 'take db offline' panel became unfrozen.
Also, close any query windows you may have open that are connected to the database in question ;)
I tried all the suggestions below and nothing worked.
EXEC sp_who
Kill < SPID >
ALTER DATABASE SET SINGLE_USER WITH Rollback Immediate
ALTER DATABASE SET OFFLINE WITH ROLLBACK IMMEDIATE
Result: Both the above commands were also stuck.
4 . Right-click the database -> Properties -> Options
Set Database Read-Only to True
Click 'Yes' at the dialog warning SQL Server will close all connections to the database.
Result: The window was stuck on executing.
As a last resort, I restarted the SQL server service from configuration manager and then ran ALTER DATABASE SET OFFLINE WITH ROLLBACK IMMEDIATE. It worked like a charm
In SSMS, set the database to read-only then back. The connections will be closed, which frees up the locks.
In my case there was a website that had open connections to the database. This method was easy enough:
Right-click the database -> Properties -> Options
Set Database Read-Only to True
Click 'Yes' at the dialog warning SQL Server will close all connections to the database.
Re-open Options and turn read-only back off
Now try renaming the database or taking it offline.
For me, I just had to go into the Job Activity Monitor and stop two things that were processing. Then it went offline immediately. In my case though I knew what those 2 processes were and that it was ok to stop them.
In my case, the database was related to an old Sharepoint install. Stopping and disabling related services in the server manager "unhung" the take offline action, which had been running for 40 minutes, and it completed immediately.
You may wish to check if any services are currently utilizing the database.
Next time, from the Take Offline dialog, remember to check the 'Drop All Active Connections' checkbox. I was also on SQL_EXPRESS on local machine with no connections, but this slowdown happened for me unless I checked that checkbox.
SSMS, especially if running it from your own desktop remotely and not directly within the database server, can be a reason for the long delays in detaching a database. For some reason SSMS may not be able to disconnect any existing "connections" to the database.
We found the process was almost instant when we did it directly from the database server itself. And in fact it killed the attempt from my own desktop SSMS session, and it "took over" and detached the database.
Nothing else suggested here worked.
Thanks
In my case i stopped Tomcat server . then immediately the DB went offline .