I m getting the above error when running the Web Job in multi-threaded environment. I m calling one stored procedure to perform some action, stored procedure has code which Inserts/Updates/Delete records from pretty big temporal tables(3-4M records[not sure if its relevant here]). Every time the job is run it deals with(Insert/Update) around 40K-80K records based on condition. When the single thread is running everything goes fine. But as soon as number of parallel jobs count is set to 2 or more I m getting the error. From initial analysis seems like issue is with Auto generated column values with for SysStartTime and SysEndTime in history table. I have tried one of the solution from internet to reduce 1 second from the date to be saved in those columns as below
DEFAULT (dateadd(second,(-1),sysutcdatetime()))
But its not working. I have read few articles where it says temporal tables does not work properly in multi-threaded environment. Now I m not sure why the issue is happening and how to resolve this in multi-threaded environment.
Can someone here please help me understanding the reason behind the error and how to fix it.
NOTE: I can't make my code to run on single thread. Minimum three threads are required. Converting to single thread is not solution in this case.
Ok, I got an weird problem: I got two server-side api, one is to select data from A table; the Other one is to Insert new record to B table with part of the data and PK from first one. They should not have any problem to each other with the Usual actions.
Somehow, I detected someone which called my select and insert function at less than 0.005 sec on my SQL monitor, which caused S-IX deadlock. So I searched the Internet and found an solution that told me to enable the Snapshot isolation. But I tried it on my test DB(which its total size is about 223MB), that Alter Database command does not show any sight of finishing after 1 hour execution, so this is intolerable to execute it on the Production DB with such long Downtime(Which its data size is bigger than the Test one).
So my question is: Does anyone know the Other way to solve the S-IX deadlock?(Without lower the Throughput.)
P.S.: My DB is SQL Server 2008
Someone was botnetting my httpd as a result my website to go down, the cpu to hit 100% and the error log to get spammed of "not enough threads left or w/e" and once I blocked all the non-cloudflare IPs, the DDoS has stopped.
He's now back though ... with sql flood. Whenever I leave my httpd open he's sql flooding my server and sqlservr process is the one which hits 100% in cpu now. I made a website copy on a sub-folder and disabled all the sql executions from the main website so everything is fine but I need a proper solution... so I must find out what sql stuff he's actually executing so I can disable or limit them.
Any ideas about how I can find all the sql executions which takes place through my web ? I remember I had a tool years ago which used to inform me about every "sql executions through web", in real time... but I forgot its name.
Any advice ?
Below is an example of a query to glean a summary of the most frequently executed queries since the instance was started.
SELECT TOP (100) qs.execution_count,
SUBSTRING(qt.text,qs.statement_start_offset/2 +1,
(CASE WHEN qs.statement_end_offset = -1
THEN LEN(CONVERT(nvarchar(max), qt.text)) * 2
ELSE qs.statement_end_offset end -
qs.statement_start_offset
)/2
) AS query_text
, DB_NAME (qt.dbid) AS dbname
, qs.total_rows
, qs.total_physical_reads
, qs.total_worker_time
FROM sys.dm_exec_query_stats AS qs
CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) AS qt
ORDER BY
qs.execution_count DESC;
For details of individual queries, you'll need a SQL Trace or Extended Event trace of batch and RPC completed events. The script for the SQL Trace can be created from Profiler (File-->Export-->Script trace definition). Customize the script after saving (file path, file size, rollover files) and execute.
I am having this big database on one MSSQL server that contains data indexed by a web crawler.
Every day I want to update SOLR SearchEngine Index using DataImportHandler which is situated in another server and another network.
Solr DataImportHandler uses query to get data from SQL. For example this query
SELECT * FROM DB.Table WHERE DateModified > Config.LastUpdateDate
The ImportHandler does 8 selects of this types. Each select will get arround 1000 rows from database.
To connect to SQL SERVER i am using com.microsoft.sqlserver.jdbc.SQLServerDriver
The parameters I can add for connection are:
responseBuffering="adaptive/all"
batchSize="integer"
So my question is:
What can go wrong while doing this queries every day ? ( except network errors )
I want to know how is SQL Server working in this context ?
Further more I have to take a decicion regarding the way I will implement this importing and how to handle errors, but first I need to know what errors can arise.
Thanks!
Later edit
My problem is that I don't know how can this SQL Queries fail. When i am calling this importer every day it does 10 queries to the database. If 5th query fails I have to options:
rollback the entire transaction and do it again, or commit the data I got from the first 4 queries and redo somehow the queries 5 to 10. But if this queries always fails, because of some other problems, I need to think another way to import this data.
Can this sql queries over internet fail because of timeout operations or something like this?
The only problem i identified after working with this type of import is:
Network problem - If the network connection fails: in this case SOLR is rolling back any changes and the commit doesn't take place. In my program I identify this as an error and don't log the changes in the database.
Thanks #GuidEmpty for providing his comment and clarifying out this for me.
There could be issues with permissions (not sure if you control these).
Might be a good idea to catch exceptions you can think of and include a catch all (Exception exp).
Then take the overall one as a worst case and roll-back (where you can) and log the exception to include later on.
You don't say what types you are selecting either, keep in mind text/blob can take a lot more space and could cause issues internally if you buffer any data etc.
Though just a quick re-read and you don't need to roll-back if you are only selecting.
I think you would be better having a think about what you are hoping to achieve and whether knowing all possible problems will help?
HTH
We got a legacy vb.net applicaction that was working for years
But all of a sudden it stops working yesterday and gives sql server timeout
Most part of application gives time out error , one part for example is below code :
command2 = New SqlCommand("select * from Acc order by AccDate,AccNo,AccSeq", SBSConnection2)
reader2 = command2.ExecuteReader()
If reader2.HasRows() Then
While reader2.Read()
If IndiAccNo <> reader2("AccNo") Then
CAccNo = CAccNo + 1
CAccSeq = 10001
IndiAccNo = reader2("AccNo")
Else
CAccSeq = CAccSeq + 1
End If
command3 = New SqlCommand("update Acc Set AccNo=#NewAccNo,AccSeq=#NewAccSeq where AccNo=#AccNo and AccSeq=#AccSeq", SBSConnection3)
command3.Parameters.Add("#AccNo", SqlDbType.Int).Value = reader2("AccNo")
command3.Parameters.Add("#AccSeq", SqlDbType.Int).Value = reader2("AccSeq")
command3.Parameters.Add("#NewAccNo", SqlDbType.Int).Value = CAccNo
command3.Parameters.Add("#NewAccSeq", SqlDbType.Int).Value = CAccSeq
command3.ExecuteNonQuery()
End While
End If
It was working and now gives time out in command3.ExecuteNonQuery()
Any ideas ?
~~~~~~~~~~~
Some information :
There isnt anything that has been changed on network and the app uses local database
The main issue is that even in development environment it donest work anymore
I'll state the obvious - something changed. It could be an upgrade that isn't having the desired effect - it could be a network component going south - it could be a flakey disk - it could be many things - but something in the access path has changed. What other problem indications are you seeing, including problems not directly related to this application? Where is the database stored (local disk, network storage box, written by angels on the head of a pin, other)? Has your system administrator "helped" or "improved" things somehow? The code has not worn out - something else has happened.
Is it possible that this query has been getting slower over time and is now just exceeded the default timeout?
How many records would be in the acc table and are there indexes on AccNo and AccSeq?
Also what version of SQL are you using?
How long since you updated statistics and rebuilt indexes?
How much has your data grown? Queries that work fine for small datasets can be bad for large ones.
Are you getting locking issues? [AMJ] Have you checked activity monitor to see if there are locks when the timeout occurs?
Have you run profiler to grab the query that is timing out and then run it directly onthe server? Is it faster then? Could also be network issues in moving the information from the database server to the application. That would at least tell you if it s SQl Server issue or a network issue.
And like Bob Jarvis said, what has recently changed on the server? Has something changed in the database structure itself? Has someone added a trigger?
I would suggest that there is a lock on one of the records that you are trying to update, or there are transactions that haven't been completed.
I know this is not part of your question, but after seeing your sample code i have to make this comment: is there any chance you could change your method of executing sql on your database? It is bad on so many levels.
Perhaps should you set the CommandTimeout property to a higher delay?
Doing so will allow your command to wait a little longer for the underlying database to respond. As I see it, perhaps are you not letting time enough for your database engine to perform all what is required before creating another command to perform your update.
Know that the SqlDataReader continues to "SELECT" while feeding the in-memory objects. Then, while reading, you require your code to update some other table, which your DBE just can't handle, by the time your SqlCommand requires, than times out.
any chances of a "quotes" as part of the strings you are passing to queries?
any chances of date dependent queries where a special condition is not working anymore?
Have you tested the obvious?
Have you run the "update Acc Set AccNo=#NewAccNo,AccSeq=#NewAccSeq where AccNo=#AccNo and AccSeq=#AccSeq" query directly on your SQL Server Management Studio? (Please replace the variables with some hard coded values)
Have you run the same test on another colleague's PC?
Can we make sure that the SQLConnection is working fine. It could be the case that SQL login criteria is changed and connection is getting a timeout. It will be probably more helpful if you post the error message here.
You can rewrite the update as a single query. This will run much faster than the original query.
UPDATE subquery
SET AccNo = NewAccNo, AccSeq = NewAccSeq
FROM
(SELECT AccNo, AccSeq,
DENSE_RANK() OVER (PARTITION BY AccNo ORDER BY AccNo) NewAccNo,
ROW_NUMBER() OVER (PARTITION BY AccNo ORDER BY AccDate, AccSeq)
+ 10000 NewAccSeq
FROM Acc) subquery
After HLGEM's suggestions, I would check the data and make sure it is okay. In cases like this, 95% of the time it is the data.
Make sure disk is defragged. Yes, I know, but it does make a difference. Not the built-in defragger. One that defrags and optimizes like PerfectDisk.
This may be a bit of a long shot, but if your entire application has stopped working, have you run out of space for the transaction log in your database? Either it's been specified to an absolute size, and that has been reached, or your disk is just full.
May be your tables include more information, and defined SqlConnection.ConnectionTimeout property value in config file with little value. And this value isn't necessary to execute your queries.
you can trying optimize your queries, and also rebuilt indexes.