I have at small web-application that get some data from a SQLdb in Visual Studio 2010. When i try to display this, using a simple dropdownlist it takes around 15 sec the first time just after compilation and then after that 5 sec every request. I use a LINQ connection to db and a repeater to print everything out. It´s four columns and around 50 rows, so not so mutch data. It doesn´t matter if i try take 10 rows, same response time.
We have tested the same thing on another computer with VS2008 installed and the time was like 0.1 sec or something like that. I use .NET 3.5 and have installed all the latest updates (SP1 and so).
If i look at the trace i see it takes time at these rows in my code:
var cust = dbContext.Customers
.Select(c => new
{
c.customerID,
c.Email
}).Take(10);
repeater.DataSource = cust;
repeater.DataBind();
Anybody know what could be taking som mutch time?
Regards
Daniel
I have tried this other aproach:
SqlConnection connection = new SqlConnection(connectionString);
SqlCommand cmd = new SqlCommand();
cmd.Connection = connection;
cmd.CommandType = CommandType.Text; //default
cmd.CommandText = "SELECT Email FROM Customer";
cmd.Connection.Open();
cmd.ExecuteNonQuery();
cmd.Connection.Close();
It takes just as long.. there must be some other more fundamental problem than the code to call the db i think?
Some more information:
I did som trace, this is first time page is loaded:
Begin Raise ChangedEvents 0,00219604937555932 0,000014
After repeater has printed 15,8138335259613 15,811637
End Raise ChangedEvents 15,8138801733289 0,000047
Second time:
Begin Raise ChangedEvents 0,00219604937555932 0,000014
After repeater has printed 5,25090396258066 5,248825
End Raise ChangedEvents 25095106283536 0,000047
What´s happening at ChangeEvents?
Get the actual SQL being generated by LINQ, copy-paste it to your database management tool and look at the execution plan to identify potential performance issues.
You can see the actual SQL by using Log property of the data context. In a console application, you can do this:
dbContext.Log = Console.Out;
// ...
Or, write the SQL to file like this:
using (var writer = new StreamWriter("sql.log")) {
dbContext.Log = writer;
// ....
}
Also, it might be worth adding ToList() or ToArray() at the end of your LINQ expression, just to make sure it is not unintentionally re-executed.
I have no idee what i did to make it work.. just kept on doing stuff at other places in the code and updated latest windows update.. hmm.. now it work like a charm, must be a bug in VS2010??
Thanks for all suggestions though, learned some great stuff!
Regards
Related
I have a query to a DB2 database on an iSeries that I wish to run from a C# program. The query is:
SELECT C.CLINO, SUM(T.VALUE) AS VALUE
FROM GTDATA.CLIENT AS C
INNER JOIN TABLE(GETHOLDDTL(C.CLINO,20150630,'','Y','Y','','','','','','','','','','M')) AS T ON T.CLIENT = C.CLINO
GROUP BY C.CLINO
GETHOLDDTL is an SQL function supplied to us by a third party to allow us to retrieve data from their system in our own programs.
When I run the query in the iSeries interactive SQL environment, saving the output to a file to ensure that I'm getting a time for the execution over the whole dataset, it takes approximately 1.5 hours to run. This is fine, as there's a lot of data which is being calculated on the fly. The problem is that when I run my C# program, the process takes in excess of 24 hours (ie that's the point at which I gave up, when it hadn't got past this point the morning after I started execution).
The C# code I'm using to execute the query is:
var conn = new OdbcConnection();
conn.ConnectionString = #"FILEDSN=S:\qsys2.dsn;UID=XXXXXXX;PWD=XXXXXXXX";
conn.ConnectionTimeout = 0;
conn.Open();
var com = new OdbcCommand(selectCommand, conn);
var reader = com.ExecuteReader();
var dt = new DataTable();
dt.Load(reader);
conn.Close();
The delay is happening on the dt.Load() line - this is presumably where the query is actually executed?
What might account for the difference? Is there a better way to implement this? If necessary, I can produce the data using the interactive SQl environment, and change my C# code to use the file that produces, but I'm trying to get this to run without any user interaction so I'd like to avoid that if possible.
Thanks for any help.
I am running into issues working with a very large table from C# .Net 4.0.
For reference the table has ~120 Million rows.
I can't do even a simple query like
SELECT TOP(50) *
FROM TableName
WHERE CreatedOn < '2015-06-01';
From code it will timeout (Default setting - 15 seconds I believe), but in SSMS it is instant.
There is an index on the column in the WHERE clause. I have also tried explicitly casting the string to a DateTime, and using a DateTime parameter instead of a literal value.
I tried a different query that filters by the PK (bigint, identity, clustered index) If I do something like "Where TableRowID = 1" it works fine from code, but if I try to use "<" or "<=" instead it will timeout (returns instantly in SSMS), regardless of how many rows are turned.
The execution plans are very simple and are exactly the same.
I have tried changing ARITHABORT but that has had no effect.
I tried having the Application connect with my own account (SSPI) instead of its own credentials with no effect.
I have been researching this issue for a few days, but everything I have found blames different execution plans.
Does anyone have any idea what could be causing this issue?
The .Net code looks like this:
private DataSet ExecuteQuery(string query, string db, List<SqlParameter> parms = null)
{
string connectionString = ConfigurationManager.ConnectionStrings[db].ToString();
SqlConnection con = new SqlConnection(connectionString.Trim());
SqlDataAdapter sqlDataAdapter = new SqlDataAdapter();
try
{
con.Open();
DataSet ds = new DataSet();
sqlDataAdapter.SelectCommand = new SqlCommand(query, con);
sqlDataAdapter.SelectCommand.CommandType = CommandType.Text;
if (parms != null)
{
foreach (SqlParameter p in parms)
{
sqlDataAdapter.SelectCommand.Parameters.Add(p);
}
}
sqlDataAdapter.Fill(ds);
if (ds.Tables.Count > 0 && ds.Tables[0].Rows.Count > 0)
{
return ds;
}
return null;
}
finally
{
if (sqlDataAdapter != null)
sqlDataAdapter.Dispose();
if (con != null)
con.Dispose();
}
}
The error message I get in .Net is the standard timeout message:
Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.
Here are my experience when dealing the issues.
Very C# sql code passed to sql server is
SELECT TOP(50) *
FROM TableName
WHERE CreatedOn < '2015-06-01'
Make sure the criteria. If it takes "instant time" to retrieve records on SSMS, the sql statement and db optimization is ok.
As other people have pointed out, you should post your C# codes and see what happens. There could be other issues. Could that be network? Could that be web.config? Do you call directly from C# code? Do you call via web service?
when you said time out? Does it time out at the time you execute the query. There is very little information you provide. Do you use third party routines (such as written by vendor or your company) to execute queries? If it possible, put the break point at the code that execute sql statement. What I mean is dig all the way to native codes, and put the break codes.
120 million records. Looks like the database has be optimized if it runs very fast on SSMS. I would take look outside SQL server.
good luck
My first step there would be to look at what your code is sending to the sql server. I'd begin by running the sql profiler. if you're not familiar with it. Here is a link on how to use it.
https://www.mssqltips.com/sqlservertip/2040/use-sql-server-profiler-to-trace-database-calls-from-third-party-applications/
After this you may want to look into network traffic times between the 2 servers.
Then look at IIS and see how it's setup. Could be a setting is wrong.
Check the error logs and see if you have any errors as well.
When you execute code in SSMS, the system is setting some default values on your connection. Specifically, look at Tools --> Options --> Query Execution --> Sql Server --> Advanced (and also ANSI). These statements are executed on your behalf when you open a new query window.
When you create your connection object in C#, are you setting these same options? If you don't explicitly set them here, you are taking the default values as defined in the actual SQL Server instance. In SSMS, you can get this by viewing the properties of the server instance and choosing the Connections page. This shows the default connection options.
You can also get this information without using the UI (you can do this in a separate application that uses the same connection string, for example). This article on MSSQLTips should guide you in the right direction.
Before I start, I'll let you know that I tried everything that has already been suggested on previous questions and other websites before I considered posting a question myself. As it happens, nothing seems to work and I'm just about fed up with this.
As some background information, this is for my Computing A2 project, so I'm kind of stuck for time now - i.e. I can't be changing loads of my code ideally.
Anyway, onto the issue...
I'm using SQLCe in my code to read from various tables and write to one. So far, the code for reading from the tables works fine, so that's any connection issues out the way first. The piece of code I am struggling with is as follows:
string connectionString = Properties.Settings.Default.BookingSystemDatabaseConnectionString;
using (SqlCeConnection myConnection = new SqlCeConnection(connectionString))
{
myConnection.Open();
try
{
string commandStr = "INSERT INTO bookings(username, room, time) VALUES(#username, #room, #time)";
SqlCeCommand myCommand = new SqlCeCommand(commandStr);
//Passes parameters into SQL command.
myCommand.Parameters.AddWithValue("username", StaticUser.StudentUser.username);
myCommand.Parameters.AddWithValue("room", roomBox.Text);
myCommand.Parameters.AddWithValue("time", timeBox.Text);
//Executes SQL command. Returns the number of affected rows (unecessary for my purposes; a bi-product if you will).
myCommand.ExecuteNonQuery();
}
catch
{
System.Windows.Forms.MessageBox.Show("Could not write new booking to database. This is likely because the database cannot be reached.", "Error");
Program.AccessError = true;
}
myConnection.Close();
}
This is just one of the many ways I have tried to combat the issue I am having. I have also explored:
myCommand.Parameters.Add(new SqlCeParameter("username", StaticUser.StudentUser.username));
to pass the parameters...and another method which escapes me now (using ".Value = StaticUser.StudentUser.username" I think). Furthermore, I have tried using a 'using' statement for the command to save me closing the connection myself (I will probably end up using a solution that uses 'using'). Finally (albeit this isn't a chronological recollection), I tried:
SqlCeCommand myCommand = new SqlCeCommand("INSERT INTO bookings(username, room, time) VALUES(#username, #room, #time)", myConnection)
Again, of course, to no avail.
To highlight the actual symptoms of the issue I am having: The code appears to run fine; stepping through the full method I have pasted above shows that no error is being caught (of course, the message box does not appear - I realised afterwards that stepping through was arguably an unnecessary procedure) and in the other methods I have touched on, the same thing happens. The issue, then, is that the table 'bookings' is not actually being updated.
So, my question, why?
I didn't do the obvious and check the Debug folder for an updated database.
Look for a copy of the database file in your bin/debug folder.
Use full path in connection string, and preferably do not include the sdf file in your project (or at least set build action to None)
i think you are not defining a connection for the command
try
mycommand.connection = connectiostring;
A SQL select statement gets run when a user presses a button on my website, and I do this:
connection = new OleDbConnection();
connection.ConnectionString = [connection string];
connection.Open();
cmd = profile.Execute(mySQLStatement);
da = new OleDbDataAdapter(cmd);
table = new DataTable();
da.Fill(table);
90% of the time, this works just fine. But every once in a while, I get the OleDbException table or view does not exist on the line da.Fill(table). There doesn't seem to be a pattern of when this works and when it doesn't, though it's more likely to not work when the site isn't used for a minute or two... Like the session might be expiring. But the rest of the website (that does not require this database) works.
Any ideas of what might be happening or how to fix it?
I have not found a solution. As a temporary fix, whenever this happens, I just re-start the page.
Sometimes the content of mySqlStatement is not exactly correct, maybe?
Trap the exception dump mySqlStatement to a logfile (with date and time this happened), and then throw.
I have created a query which is: SELECT Replace(column_name,a,b) AS expr1
FROM table1; the name of this query is:filepath.
I have wrote the following code in C#. when i compile the code it Syntax error in PROCEDURE clause.
OleDbCommand cmd1 = new OleDbCommand();
cmd1.Connection= ren_connection1;
cmd1.CommandType = CommandType.Text;
cmd1.CommandText = "Execute filepath";
OleDbParameter oldfilevalue = new OleDbParameter();
oldfilevalue.ParameterName = "a";
oldfilevalue.OleDbType = OleDbType.VarChar;
oldfilevalue.Direction = ParameterDirection.Input;
oldfilevalue.Value = oldname2;
OleDbParameter newfilevalue = new OleDbParameter();
newfilevalue.ParameterName = "b";
newfilevalue.OleDbType = OleDbType.VarChar;
newfilevalue.Direction = ParameterDirection.Input;
newfilevalue.Value = oldname1;
cmd1.Parameters.Add(oldfilevalue);
cmd1.Parameters.Add(newfilevalue);
i = cmd1.ExecuteNonQuery();
//oldefile value can be like this: D:/myfile/pictures/cars/
//newfile value can be like this: D:/myfile/pictures/jeeps/
i want to replace in a row a string with another string without modifying the whole row..and i thought replace will work but it didnt :(
access version is:2007.
any idea or help will be greatly appreciated.
Thanks alot.
I am afraid Replace is only available if you are running within Access, as Vincent mentions, it is a VBA function, not a Jet/ACE function. Also discussed: Exception when trying to execute "REPLACE" against MS Access. I have replied to what i think is your first question, update table access, with a possible solution.
Try changing your commandtext with
cmd1.CommandText = "EXECUTE yourProcedureName";
Edit now that your procedure is invoked correctly you need to work around the missing "Replace" function (btw, have you tried Vincent Vancalbergh's suggestion to see if "Replace can be made to work? That would be much easier....)
What I was saying in the comments is that you could select the content of the table, perform the replace in c# code and (if needed) update your table with the new values.
your select becomes:
SELECT table1_id, column_name FROM table1;
and your code changes like this:
//you should change ExecuteNonQuery to ExecuteReader, since you want
// to read the results of your SELECT
OleDbDataReader rdr= cmd1.ExecuteReader();
//Iterate through the table
while(rdr.Read())
{
string currentValue=rdr["column_name"].ToString();
string newValue = currentValue.Replace(a, b);
//now do what you need with the row
// ...
}
I found the following here:
Prior to a company wide upgrade to XP
there was no problem with access
databases, so I am not sure if this
would be a solution to your issue. But
I had a problem similar to yours after
an upgrade to XP from 2000 with some
access databases. Undefined Function
"Replace" errors started to pop up. At
the end of the day it turned out to be
the version of VBA installed. 6.0
versus 6.3. The problem machines had
6.0 installed. Start access Help -> About MS Access -> SYSTEM INFO ->
APPLICATIONS -> Microsoft Access 2000
-> SUMMARY. The VBA version of 6.00 produced the error, VBA version 6.03
no problem. Take Care, Nick
Now the question is, what VBA version are you using?
The solution is in #onedaywhen's answer her:
Exception when trying to execute "REPLACE" against MS Access
It uses Mid(), Len() and InStr() in place of Replace().