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.
Related
I'm working with a moderately sized database of about 60,000 records. I am working on building a mobile application which will be able to check out a single table into a compact .sdf on for viewing and altering on the device, then allow the user to sync their changes back up with the main server and receive any new information.
I have set it up with the Sync Framework using a WCF Service Library. When setting up the connection for some reason the database won't let me check "Use SQL Server Change Tracking" and throws up the error:
"'Unable to initialize the client database, because the schema for table 'Inventory' could >not be retrieved by the GetSchema() method of DbServerSyncProvider. Make sure that you can >establish a connection to the client database and that either the >SelectIncrementalInsertsCommand property or the SelectIncrementalUpdatesCommand property of >the SyncAdapter is specified correctly."
So I leave it unchecked and set it to use some already created columns "AddDateTime" and "LastEditTime" it seems to work okay, and after a massive amount of tweaking I have it partially working. The changes on the device sync up perfectly with the database, updates, deletes, all get applied. However, changes on the server side...never get updated. I've made sure everything is set up right with the bidirectional setup so that shouldn't be the problem. And, I let it sit overnight so the database received ~500 new records, this morning it actually synced the latest 24 entries to the database...out of 500 new. So that should be further proof that it's able to receive information from the server, but for all useful purposes, it's not.
I've tried pretty much everything and I'm honestly getting close to losing it. If anyone has any ideas they can throw out I can chase after I would be most grateful.
I'm not sure if I just need to go back and figure out why I can't do it with the "SQL Server Change Tracking". Or if there is a simple explanation for why it's not actually syncing 99% of the changes on the server back to the client.
Also, the server database table schema can't be altered as a lot of other services use it. But the compact database can be whatever the heck in needs to be to just store the table and sync properly in both directions.
Thank you!!
Quick Overview:
Using WCF and syncing without SQL Server Change Tracking (Fully enabled on server and database)
Syncing changes from client to server works perfectly
Syncing from server back to the client not so much: out of 500 new entries overnight, on a sync it downloaded 24.
EDIT: JuneT got me thinking about the time and their anchors. When I synced this morning it pulled 54 of about 300 new added records. I went in to the line (there are about 60 or so columns, so I removed them for readability, this is kind of a joke)
this.SelectIncrementalUpdatesCommand.CommandText = #"SELECT [Value], [Value], [Value] FROM >TABLE WHERE ([LastEditDate] > #sync_last_received_anchor AND [LastEditDate] <= >#sync_new_received_anchor AND [AddDateTime] <= #sync_last_received_anchor)";
And replaced #sync_last_received_anchor with two DIFFERENT times. Upon syncing it now returns the rows trapped between those two and took out the middle one giving me:
this.SelectIncrementalUpdatesCommand.CommandText = #"SELECT[Value], [Value], [Value] FROM >TABLE WHERE ([LastEditDate] > '2012-06-13 01:03:07.470' AND [AddDateTime] <= '2012-06-14 >08:54:27.727')"; (NOTE: The second date is just the current time now)
Though it returned a few hundred more rows than initially planned (set the date gap for 600, it returned just over 800). It does in fact sync the client up with the the new server changes.
Can anyone explain why I can't use #sync_last_received_anchor and what I should be looking for. I suppose I could always add box that allows the user to select the date to begin updating from? Or maybe add some sort of xml file to store the sync date that would be updated anytime a sync was -successfully- completed?
Thanks!
EDIT:
Ran the SQL profiler on it...the date (#sync_last_received_anchor) is getting set to 8 hours ahead of whatever time it really is. I have no idea how or why it's doing this, but that would definitely make sense.
Turns out the anchors are collected like this:
this.SelectNewAnchorCommand.CommandText = "Select #sync_new_received_anchor = GETUTCDATE()";
That UTC date is what was causing the 8 hours gap. To fix it either change it to GETDATE(), or convert your columns to UTC time in the WHERE clause of the commands.
After spending many hours with many cups of coffee, I've figured out how to solve this error of mine. While I was running the code on desktop testing area, everything seemed to be working perfectly; however the same code and webservice on target device gave this error repeatedly. Then, suddenly, the "dbo_" prefixes on compact database table names started looking interesting, like they were trying to tell me something really important. So, I've listened...
Configuration.SyncTables.Add("Products);
on ClientSyncAgent.cs should be changed to
Configuration.SyncTables.Add("dbo_Products");
[Exeunt]
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
I'm part of a team writing an ERP using , Seam, and Jboss, and on one of my pages, I keep getting an SQL error: 8152 whenever I try to input something. SQL error:8152, for those of you who don't know, is when you try to input a value over the maximum limit of the column.
I've double checked my entity and the database, and their maximum value limits are the same (50 nvarchars). In addition, I'm pretty sure that we're not using audit tables. I then put System.out.println(""); all over the place, and found that the error was happening in between these two println(s):
System.out.println("Flushing");
entityManager.flush();
System.out.println("Flushing complete");
Which is part of a method that process all changes to the table. But I'm pretty new to programming and not sure what's going on.
Any help would be appreciated, thanks in advance, Jeff.
P.s. Code on request, but I didn't post it because there is a lot of it all over the place.
I would verify the SQL that is being executed when the flush() is performed. That way you can see the length of your data and verify that it is too big as shown by the DB error.
If you are using Hibernate, you can output SQL to the console. You don't say what your DB is, but if it's SQL Server you can use the profiler to see what SQL is being executed.
I have made an update statement in a table in SQL 2008 which updated the table with some wrong data.
I didn't have a backup for the DB.
It's some important dates which got updated.
Is there anyway where i can recover the old data from the table.
Thanks
SNA
Basically no unless you want to use a commercial log reader and try go through it with a fine tooth comb. No backup of the database can be an 'update resume, leave town' scenario - harsh but it just should not happen.
Andrew basically has called it. I just want to add a few ideas you can consider if you are desperate:
Are there any reports or printouts lying around? Perhaps you can reconstruct the data from there.
Was this data entered via a web application? If so, there is a remote chance you can find the original data in the web server logs, depending upon how the app was constructed, etc.
Does this app interface (pass data to) any other applications? They may have a buffered copy of data...
Can the data be derived from any other existing data? Is there an audit log table, or another date in your schema based on this one, from which you can reconstruct the original date?
Edit:
Some commenters are mentioning that is is a good idea to test your update/delete statements before running them. For this to become habit, it helps if you have an easy method. I usually create my DELETE statements like this:
--delete --select *
from [User]
where UserID=27
To run the select in order to test your query, highlight everything from select onwards. To then run the delete if you are satisfied with the filter criteria, highlight everything from delete onwards. The two dashes in front of delete are so that if the query accidentally gets run, it will just crash due to invalid syntax.
You can use a similar construct for UPDATE statements, although it is not quite as clean.
SQL server keeps log for every transation.So you can recover your modified data from the log as well without backup.
Select [PAGE ID],[Slot ID],[AllocUnitId],[Transaction ID]
,[RowLog Contents 0], [RowLog Contents 1],[RowLog Contents 3],[RowLog Contents 4]
,[Log Record]
FROM sys.fn_dblog(NULL, NULL)
WHERE
AllocUnitId IN
(Select [Allocation_unit_id] from sys.allocation_units allocunits
INNER JOIN sys.partitions partitions ON (allocunits.type IN (1, 3)
AND partitions.hobt_id = allocunits.container_id) OR (allocunits.type = 2
AND partitions.partition_id = allocunits.container_id)
Where object_id=object_ID('' + 'dbo.student' + ''))
AND Operation in ('LOP_MODIFY_ROW','LOP_MODIFY_COLUMNS')
And [Context] IN ('LCX_HEAP','LCX_CLUSTERED')
Here is the artcile, that explains step by step, how to do it.
http://raresql.com/2012/02/01/how-to-recover-modified-records-from-sql-server-part-1/
Imran
Thanks for all the responses.
The problem was actually accidentally ---i missed to select the where condition in the update statement.---Rest !.
It was a quick 5 minutes task --Like just changing the date to test for one customer data--so we didn't think of taking a backup.
Yes of course you are true ..This is a lesson.
Now onwards i will be careful to write "my update statements in a transaction." or "test my update statements"
Thanks once again--for spending your time to give some insight rather ignoring the question since the only answer is "NO".
Thanks
SNA
Always take a backup before major UPDATE statements, even if it's not used, there's the peace of mind
Especially with Red Gate's Object Level Restore, one can restore individual table/row now given a backup file
Good luck, I'd suggest finding an old copy elsewhere (DEV/QA) etc...
Isn't it possible to do a rollback on an UPDATE statement?
Late one but hopefully useful…
If database is in full recovery mode then all transactions are logged in transaction log and can be retrieved. Problem is that this is not natively supported because this is not the main purpose of the transaction log.
Options are:
Commercial tools such as Apex Log (more expensive, more options) or Quest Toad (less expensive, less options for this purpose main focus is on SQL Server management)
Trying to do this yourself, like user1059637 pointed out. Problem with this approach is that it can’t read transaction log backups and is more tedious.
It comes down to how much your data is worth to you in terms of time and $.
I'm trying to pull user data from 2 tables, one locally and one on a linked server, but I get the wrong results when querying the remote server.
I've cut my query down to
select * from SQL2.USER.dbo.people where persId = 475785
for testing and found that when I run it I get no results even though I know the person exists.
(persId is an integer, db is SQL Server 2000 and dbo.people is a table by the way)
If I copy/ paste the query and run it on the same server as the database then it works.
It only seems to affect certain user ids as running for example
select * from SQL2.USER.dbo.people where persId = 475784
works fine for the user before the one I want.
Strangely I've found that
select * from SQL2.USER.dbo.people where persId like '475785'
also works but
select * from SQL2.USER.dbo.people where persId > 475784
brings back records with persIds starting at 22519 not 475785 as I'd expect.
Hope that made sense to somebody
Any ideas ?
UPDATE:
Due to internal concerns about doing any changes to the live people table, I've temporarily moved my database so they're both on the same server and so the linked server issue doesn't apply. Once the whole lot is migrated to a separate cluster I'll be able to investigate properly. I'll update the update once this happens and I can work my way through all the suggestions. Thanks for your help.
The fact that LIKE operates is not a major clue: LIKE forces integers to string (so you can say WHERE field LIKE '2%' and you will get all records that start with a 2, even when field is of integer type). Your incorrect comparisons would lead me to think your indexes are corrupt, but you say they work when not used via the link... however, the selected index might be different depending on the use? (I seem to recall an instance when I had duplicate indexes and only one was stale, although that was too long ago to recall the exact cause).
Nevertheless, I would try rebuilding your index using the DBCC DBREINDEX (tablenname) command. If it turns out that doing so fixes your query, you may want to rebuild them all: here is a script for rebuilding them all easily.
Is dbo.people a table or a view? I've seen something similar where the underlying table schema had been changed and dropping and recreating the view fixed the problem, although the fact that the query works if run directly on the linked server does indicate something index based..
Is the linked server using the same collation? Depending on the index used, I could see something like this perhaps happening if the servers were not collation compatible, but the linked server was set up with collation compatible (which tells Sql Server it can run the query on the remote server).
I would check the following:
Check your definition on the linked server, and confirm that SQL2 is the
server you expect it to be
Check and compare the execution plans both from the remote and local servers
Try linking by IP address rather than name, to ensure you have the proper machine
Put the code into a stored procedure on the remote machine, and try calling that instead
Sounds like a bug to me - I;ve read of some issues along these lines, btu can't remember specifically what. What version of SQL Server are you running?
select * from SQL2.USER.dbo.people where persId = 475785
for a PersID which fails how does:
SELECT *
FROM OpenQuery(SQL2, 'SELECT * FROM USER.dbo.people WHERE persId = 475785')
behave?