I have a SQL Server service and multiple Windows Service doing some backgrounds work on same server.
One of them (I'm calling it "A") have a routine executing "single_user/offline" and "online/multi_user" to active databases to do some backup operations at midnight. The another ones executes multiple queries over that databases (I'm calling it "B").
The problem is the following:
1.- Windows Service "A" executes SET ONLINE.
2.- Windows Service "B" executes a random SELECT.
3.- Windows Service "A" tries to execute SET MULTI_USER. This execution is dropped because there is an active connection made from Windows Service "B".
I've tried executing SET ONLINE and SET MULTI_USER on same CommandText of the SqlCommand, but this doesn't denies the incoming query from Windows Service "B", breaking my process and keeping the database locked (because the SINGLE_USER).
How can I make an ONLINE and MULTI_USER commands at same time on the Windows Service "A" to make Windows Service "B" being cancelled or wait the process finished? (It's not a problem that Windows Service "B" being cancelled)
Could be sp_dettach_db or sp_attach_db useful?
It sounds like Service A is closing it's connection after bringing the database into Single User mode. This frees up Service B to become the single user, at which point Service A can no longer change the mode until it can grab the single connection back, which it won't be able to do as long as Service B, or any other client for that matter, has it.
I can think of a couple of things you could do here:
Once your offline operations are complete, begin polling until Service A can become the single user again
Find the SPID of the connection from Service B and kill it.
See the limitations and restrictions section about single user mode at this link for more info.
Thanks to all, but I reanalyzed the problem I was having from the beginning, and concluded that the action "SET SINGLE_USER" was not necessary, since the process does not require actions in that mode, so finally with the action "SET OFFLINE" and "SET ONLINE" could prevent intermediate connection problems.
Related
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 want to use nHibernate in a windows service. If the systems boots, it might start my service before the database. In that case, configuration of nHibernate fails and the service crashes. So now I'm wondering how I can check if the database service has already been started. In case it has not yet started, my service should wait a bit and try again later.
If your service always runs on the same machine as SQL Server, You should be using ServiceInstaller.ServicesDependedOn to tell Windows(SCM) that you depend on 'MSSQLSERVER' (the name of service that runs SQL Server).
From MSDN:
A service can require other services to be running before it can
start. The information from this property is written to a key in the
registry. When the user (or the system, in the case of automatic
startup) tries to run the service, the Service Control Manager (SCM)
verifies that each of the services in the array has already been
started.
ServiceInstaller is the class that is used by InstallUtil when it installs your service. Other installation packages including InstallShield also support this windows functionality. Equivalent SC command.
So your service will only start after SQL Server is already running. But even in this case, it might still be a good idea to offload all potentially long running startup procedures to the background thread. Do as little as possible in OnStart method. Ideally you would just spawn a new initialization thread that would take care of NHibernate session factory initialization. If for some reasons you still want to do this in OnStart, then you should consider retrying NHibernate initialization and calling ServiceBase.RequestAdditionalTime to avoid:
Error 1053: The service did not respond to the start or control
request in a timely fashion.
Ideally your service should not depend on the database availability because it might be running on a remote machine. The service is an 'always on' process that should tolerate intermittent database connectivity issues.
No clue if there are better ways, but in your service startup, check for the system uptime. If this is less then let's say 5 minutes, wait for (5 minutes - Uptime) and after that start the rest of the service as you normally would.
See the following for Calculating server uptime gives "The network path was not found"
This is not a solution however for when your service tries to connect to a SQL which is down, however if this happens you want to handle the exception and actually be notified that the SQL is down. Very unlikely you want the service to keep trying without you yourself beeing aware the SQL is down.
You could use ServiceController class and call its static method GetServices() to get the list of services. It will give an array of services, find the right one and check its status.
See ServiceController on MSDN
Currently I am making sure I can establish a connection to the database needed and running a default query (configurable). If this is successful I proceed to start the service.
What I've found in some cases is that even if the MSSQL service is started it doesn't guarantee that you can connect to it and execute queries against it.
PROBLEM BACKGROUND
Sorry if this is a bit tedious to read, but please bear with me.
I have been tasked to determine the most restrictive security permissions...or rather investigate if more restrictive security settings can be configured for the SQL server login our program uses, yet still function as normal.
Currently the program runs as a Windows service configured to log on using a Windows user account that has been configured in SQL server with trusted auth. The login used has been assigned a db_owner role and the service works fine like that.
So to narrow the permissions for this user I removed the db_owner rights and assigned it to the db_datareader and db_datawriter roles. Unfortunately this causes a problem and when I start up the service I get an error dialogue displaying:
Error 1053: the service did not respond to the start or control request in a timely fashion.
and in the event viewer under the System events are logged:
event 7009 (timeout waiting for..to connenct)
event 7000 (the service did not respond to the start or control )
My problem is the code base is really large and I'm not sure what exactly to look for that would require db_owner permissions (it sets permissions maybe?).
QUESTION
What should I be looking for in a program that executes SQL that would cause it to require db_owner permissions?
In case the first question is too general: is there an easy way/any tools I can use to figure out what a Windows service is trying to do during start-up 'SQL wise' if I get system error events logged:
event 7009 (Timeout (30000 milliseconds) waiting for the ... service to connect)
event 7000 (The service did not respond to the start or control request in a timely fashion).
BTW I tried running profiler with all audit events selected, but still get nothing logged when starting the service.
This is such a broad question without knowing the architecture of your service and how it communicates with SQL Server. Are you using in-line SQL? Stored Procedures?
I think you'd best tackle this issue by starting from the service's code and tracing the execution path from the start and see what is being executed on/against SQL Server.
Alternatively, if you are using stored procedures, you may want to script them all out into a file and search on some common T-SQL commands limited to a db_owner, such as CREATE, DROP, ALTER.
I'm trying to write a program that is able to import and export a specific database, plus users and logins, from a Microsoft SQL Server database. I have an abstraction layer between my code and ODBC that much of our other software uses. The abstraction layer normally runs with autocommit off and handles transactions on its own, but since the BACKUP command doesn't like being run in any transaction, I"m using another method of the layer, called executeDirect, that runs it with autocommit on.
The method uses the SQLExecDirect function to run the BACKUP command. When it's done, the function returns SUCCESS_WITH_INFO, since the BACKUP command likes to give three lines of output. The code then attempts to get the output with SQLGetDiagField and is able to gather the first line from record #1, but there is no record #2.
The last thing the method wants to do is reset the connection to autocommit off, but when it attempts that, an error occurs, saying "Connection is busy with results from another command", SQL State is "HY000". So, obviously, the connection wants to remit the other two lines of output, but I don't know how to let it do so.
The BACKUP DATABASE command works as a batch, requiring a call to SQLMoreResults to continue with the backup.
I know there is already a question about this but my issue is more oriented to remote scenarios.
With net start/stop you can specify a /y parameter to bounce users off current sessions but you cannot start/stop remotely.
With sc you can start/stop remotely but if the SQLServer instance is being used it won't let you stop the service (with a "[SC] ControlService FAILED 1051: A stop control has been sent to a service that other running services are dependent on." message)
So my question is: what's the best way of kicking out users stopping the SqlServer service remotely?
I think the /y just answers Yes to the "Are you sure?" prompt. I'd think that sc could be used as well, though it may time out waiting for the service to stop if there's a lot of inflight transactions. Does it give you any specifics of why it can't stop?
Here's a couple of other methods to stop a remote SQL instance. Except for SHUTDOWN WITH NOWAIT, I'd recommend any of them.
psexec will let you run net stop remotely.
There's also the SQL SHUTDOWN command - you can issue that WITH NOWAIT to avoid waiting for current transactions to finish and checkpointing, which will make shutdown faster (but subsequent startup slower, and could lead to lost data).
Or you could use either Configuration Manager or Management Studio to stop a remote instance.
Edit: The error is pretty self explanatory. It means you must stop dependent services first. Sql Agent is probably at least one of them. Checking Admin Tools->Services will show you the rest.
Using SSMS is the best make sure you have the proper privileges to shutdown and check to see the status of replications and ALWAYS ON and Log Shipping.