Data Read / Write Problem With Concurrent Users On With Dll
Feb 6, 2007
Hi,
I have a web app, that runs fine, except for one particular section that uses a class called by an event in the code behind. The class resides as a dll in the bin folder.
We had no problems during testing, when only one user was running this dll. Problems soon occurred when multiple users tried running it. Here's the error & stack:
06/02/2007 09:25:26 ==> cburns ==> There is already an open DataReader associated with this Command which must be closed first. at System.Data.SqlClient.SqlInternalConnectionTds.ValidateConnectionForExecute(SqlCommand command)
at System.Data.SqlClient.SqlConnection.ValidateConnectionForExecute(String method, SqlCommand command)
at System.Data.SqlClient.SqlCommand.ValidateCommand(String method, Boolean async)
at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result)
at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method)
at System.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior, String method)
at System.Data.SqlClient.SqlCommand.ExecuteReader()
at ESP.Validator.Data.DatabaseEvents.DatabaseEventManager.Read(IEventable eventObject, Int16 eventType, DateTime earliestDate, DateTime latestDate) in C:My PathValidatorValidator.NETDataDatabaseEventsDatabaseEventManager.cs:line 92
at ESP.Validator.Data.Translink.CATCard.GetDespatchDate() in C:My PathProjectsValidatorValidator.NETDataTranslinkCATCard.cs:line 94
at ESP.Validator.Data.Translink.ExistingSchemeEntitlement.ReadCards() in C:My PathProjectsValidatorValidator.NETDataTranslinkExistingSchemeEntitlement.cs:line 215
at ESP.Validator.Data.Translink.ExistingSchemeEntitlement.Read() in C:My PathProjectsValidatorValidator.NETDataTranslinkExistingSchemeEntitlement.cs:line 147
at ESP.Validator.Data.Translink.TranslinkApplicant.ReadEntitlements() in C:My PathProjectsValidatorValidator.NETDataTranslinkTranslinkApplicant.cs:line 369
at ESP.Validator.Data.Translink.TranslinkApplicant.Read() in C:My PathProjectsValidatorValidator.NETDataTranslinkTranslinkApplicant.cs:line 353
at ESP.Validator.Data.Translink.PrePrintedLetter.Read() in C:My PathProjectsValidatorValidator.NETDataTranslinkPrePrintedLetter.cs:line 282
at ESP.Validator.ValidationProcessor.Read(ValidationSubject subject) in C:My PathProjectsValidatorValidator.NETValidationProcessor.cs:line 82
at clear_applications_scan_applications.ProcessValidation()
It seems the data reader is getting reused. We have ensured after each read the reader is closed. Though all users are using the same connection string. Could it be a connection pool problem, with the connection being overwritten during execution? Should i edit it according to the users logon?
I am really at a loss for ideas, and I don't mind admitting I am a bit out of my depth with this one!!
Any ideas/suggestions would be greatly appreciated.
Hi,Is it possible to have many different clients conncecting to a web basedserver all using, simultaneously, the same DSN-less connection string heldin a server side include file?Many thanksRay Allison
I want to make data changes in read_only database , that's why i must set database read_write. While database is at read_write mode, i want to be sure that no one makes change in database.
For this aim, i write the code below, but i suspect that after setting the database read_write, till the setting database single_user ,is it possible get DML script from another user. Is the code below enough for this operation. Or is there another way?
Reminding: Read_only database can not be set single_user mode. That's why, first you must set database read_write.
The code;
use master alter database xxx set read_write with rollback immediate alter database xxx set single_user with rollback immediate
use xxx update tablexxx set columnxxx=yyy use master alter database xxx set read_only with rollback immediate alter database xxx set multi_user with rollback immediate
I was wondering if it is possible to read image data from a database in .net compact framework. Since cf does not have image.fromstream(memstream) to work with, I don't know how else to read the image from the database and then place it into a picturebox.
Here is the code I have been trying out:
Dim Img As Image ' Dim conn As New SqlCeConnection("Data Source = My Documents est2.sdf")
conn.Open()
Dim sql As String = "SELECT * FROM Dater" Dim cmd As New SqlCeCommand(sql, conn) Dim reader As SqlCeDataReader = _ cmd.ExecuteReader(System.Data.CommandBehavior.CloseConnection)
While reader.Read()
TextBox1.Text = reader.Item("name") Dim b(reader.GetBytes(1, 0, Nothing, 0, Integer.MaxValue) - 1) As Byte
reader.GetBytes(1, 0, b, 0, b.Length) Dim ms As New System.IO.MemoryStream(b) Dim bmp As New Bitmap(ms) <-Error: Value does not fall within expected range Img = bmp
End While
PictureBox2.Image = Img
I get an error ,Value does not fall within expected range.
Does this mean the image was not save correctly in the database?
I need to know how many concurrent users are allowed to access the database at any point of time.Will it depend on the type of licence?Where do we set this parameter.Some users are complaining 'time out' problem.Thanks for any help!
I need some rough figures for replication performance. Can anyone give an idea of the number of concurrent subscribers a single IIS server can safely handle before having to move to load balancing with multiple IIS servers.
I would estimate the average daily row changes to be in the region of 500 to 2500 per subscriber.
I'm contemplating a sql server archive strategy that rolls really old data off any sort of dbms and onto low cost media like dvds in a non relational archive format. I dont want to ever worry about these archives spanning different versions of sql when i go to retrieve a range of data that happens to span sql versions (eg one disc was sourced from 2005 another by 2008 but my report needs a union of both).
So I'm thinking about neutral/efficient formats for these archives and a live homegrown catalog that can determine exactly what disc(s) need to be mounted based on passed from and to date parameters...all so that the data that might span discs (and versions and maybe even schemas) can be merged and loaded into my sql version d'jour's "throw away" archive database for a one time report or other unplanned activity.
I remember raw data types being very convenient as an ETL format for our customers who have ssis, but wouldn't want our sqlexpress customers to be left without the archiving capability. Do the "things" that read and write raw data files really originate in some special T-SQL command that all sql editions can use, or is it strictly an ssis thing?
INPUT: A table contains 2 columns with data i need. column A=Filename and column B=FileContent
PROCESS: I need to loop through ea record in the table and retrieve columns A and B. Then for ea column i need to write the Content hold in column B into File hold in column A.
I so far found out, that i need a Execute SQL Task in Control Flow querying the table and get columns A and B into 2 variables, plus a 3rd var holding the object. Then the output goes into a Foreach Loop Container. From this point i don't know how to continue. I tried to put a Data Flow Task inside the Foreach Loop, but couldn't find out how i now get the 2 variables to the Data Flow Task and use them to for the file to be written and the content to be placed in the file.
Is there any example similiar to that so i could learn how to start on that?
I have a very long transaction that runs on the same database thatother users need to use for existing data. I don't care if they seedata from the transaction before it is done and am only using thetransaction because I need a way to roll it back if any errors happenduring the transaction. Unfortunately all tables affected in the longrunning transaction are completely locked and nobody else can accessany of the affected tables while it is running. I am using thetransaction isolation level of read uncommitted, which from my limitedunderstanding of isolation levels is the least strict. What can I do toprevent this from happening?Below is the output from sp_who2 and sp_lock while the process isrunning and another process is being blocked by it.SPID Status LoginHostName BlkBy DBName Command CPUTimeDiskIO LastBatch ProgramName SPID----- ------------------------------------------------------------------------------ ---------- ----------------- ---------------- ------- ------ ------------------------------------------ -----1 BACKGROUND sa. . NULL LAZY WRITER 0 006/09 15:42:52 12 sleeping sa. . NULL LOG WRITER 10 006/09 15:42:52 23 BACKGROUND sa. . master SIGNAL HANDLER 0 006/09 15:42:52 34 BACKGROUND sa. . NULL LOCK MONITOR 0 006/09 15:42:52 45 BACKGROUND sa. . master TASK MANAGER 0 506/09 15:42:52 56 BACKGROUND sa. . master TASK MANAGER 0 006/09 15:42:52 67 sleeping sa. . NULL CHECKPOINT SLEEP 0 1206/09 15:42:52 78 BACKGROUND sa. . master TASK MANAGER 0 206/09 15:42:52 89 BACKGROUND sa. . master TASK MANAGER 0 006/09 15:42:52 910 BACKGROUND sa. . master TASK MANAGER 0 006/09 15:42:52 1011 BACKGROUND sa. . master TASK MANAGER 0 106/09 15:42:52 1112 BACKGROUND sa. . master TASK MANAGER 0 006/09 15:42:52 1251 sleeping SUPERPABLOAdministratorSUPERPABLO . PM AWAITING COMMAND 1813307 06/09 16:10:34 .Net SqlClient Data Provider 5152 sleeping SUPERPABLOAdministratorSUPERPABLO 54 PM SELECT 30 506/09 16:10:16 .Net SqlClient Data Provider 5253 RUNNABLE SUPERPABLOAdministratorSUPERPABLO . master SELECT 0 306/09 16:09:44 SQL Profiler 5354 RUNNABLE SUPERPABLOAdministratorSUPERPABLO . PM UPDATE 10095206 06/09 16:10:02 .Net SqlClient Data Provider 5456 RUNNABLE SUPERPABLOAdministratorSUPERPABLO . PM SELECT INTO 151 2706/09 16:10:33 SQL Query Analyzer 56(17 row(s) affected)spid dbid ObjId IndId Type Resource Mode Status------ ------ ----------- ------ ---- ---------------- -------- ------51 5 0 0 DB S GRANT52 5 0 0 DB S GRANT52 5 1117963059 4 PAG 1:7401 IS GRANT52 5 1117963059 4 KEY (5301214e6d62) S WAIT52 5 1117963059 0 TAB IS GRANT54 5 1117963059 0 TAB IX GRANT54 5 1852025829 0 TAB IX GRANT54 5 1181963287 3 PAG 1:9017 IX GRANT54 5 1117963059 4 KEY (5301934930a4) X GRANT54 5 1117963059 3 KEY (530187fc93f3) X GRANT54 5 1117963059 4 KEY (530154df71eb) X GRANT54 5 0 0 DB [BULK-OP-LOG] NULL GRANT54 5 0 0 FIL 2:0:d U GRANT54 5 1117963059 2 KEY (1d0096c50a7d) X GRANT54 5 1117963059 2 KEY (1b004a9a6158) X GRANT54 5 1117963059 2 KEY (1800a435d44a) X GRANT54 5 1181963287 6 PAG 1:8745 IX GRANT54 5 1181963287 4 PAG 1:8923 IX GRANT54 5 1181963287 2 PAG 1:8937 IX GRANT54 5 1117963059 4 KEY (5301112b0696) X GRANT54 5 0 0 PAG 1:10889 IX GRANT54 5 1181963287 5 PAG 1:8859 IX GRANT54 5 1181963287 6 PAG 1:10888 IX GRANT54 5 0 0 PAG 1:10891 IX GRANT54 5 0 0 PAG 1:10893 IX GRANT54 5 0 0 PAG 1:10892 IX GRANT54 5 0 0 PAG 1:10894 IX GRANT54 5 0 0 PAG 1:10882 IX GRANT54 5 1117963059 3 KEY (530135fbce35) X GRANT54 5 1117963059 0 RID 1:7387:57 X GRANT54 5 1117963059 0 RID 1:7387:59 X GRANT54 5 1117963059 0 RID 1:7387:61 X GRANT54 5 1117963059 3 KEY (5301406ad2bc) X GRANT54 5 1117963059 4 PAG 1:7401 IX GRANT54 5 0 0 PAG 1:7387 IX GRANT54 5 1117963059 2 PAG 1:7389 IX GRANT54 5 1117963059 3 PAG 1:7391 IX GRANT54 5 1117963059 0 RID 1:7387:10 X GRANT54 5 1117963059 0 RID 1:7387:56 X GRANT54 5 1117963059 0 RID 1:7387:58 X GRANT54 5 1117963059 0 RID 1:7387:60 X GRANT54 5 1117963059 3 KEY (530144afbed8) X GRANT54 5 1117963059 4 KEY (530115ee6af2) X GRANT54 5 1117963059 3 KEY (5301c6cd88ea) X GRANT54 5 1149963173 0 TAB IX GRANT54 5 1181963287 0 TAB X GRANT54 5 1117963059 4 KEY (5301d2782bbd) X GRANT54 5 1117963059 3 KEY (5301015bc9a5) X GRANT54 5 0 0 DB S GRANT54 5 0 0 DB [BULK-OP-DB] NULL GRANT54 5 1117963059 4 KEY (5301501a1d8f) X GRANT54 5 1117963059 2 KEY (1c00f3a2b6c5) X GRANT54 5 1117963059 2 KEY (1a002ffddde0) X GRANT54 5 0 0 PAG 1:7411 IX GRANT54 5 1117963059 2 KEY (1900c15268f2) X GRANT54 5 0 0 PAG 1:10840 IX GRANT54 5 1181963287 4 PAG 1:10841 IX GRANT54 5 0 0 PAG 1:10842 IX GRANT54 5 1117963059 3 KEY (5301059ea5c1) X GRANT54 5 0 0 PAG 1:10820 IX GRANT54 5 1181963287 4 PAG 1:10821 IX GRANT54 5 1181963287 5 PAG 1:10874 IX GRANT54 5 1181963287 5 PAG 1:10876 IX GRANT54 5 0 0 PAG 1:10877 IX GRANT54 5 1181963287 5 PAG 1:10878 IX GRANT54 5 0 0 PAG 1:10849 IX GRANT54 5 0 0 PAG 1:10850 IX GRANT54 5 1117963059 2 KEY (1700f225b712) X GRANT54 5 1117963059 4 KEY (5301214e6d62) X GRANT56 5 0 0 DB S GRANT56 1 85575343 0 TAB IS GRANT
Does anyone know how to reserve a number of concurrent user licenses /per server logins in MSSQL 2000? I have a situation where I have more users than I have licenses for an enterprise SQL application and would like to make sure that a certain group of users always has access to the system. Individuals who only need inquiry access should only be allowed to login if there are licences available beyond the core group of users. Any Ideas? Thanks.
We are running three web sites in a clustered environmentWLBS. The web servers are connected to a Database Serverrunning MS SQL server enterprise edition licensed as perCPU license. The Windows 2000 Advanced Server Licensingmode on all the servers is per SEAT license.Our customers are accessing our web servers and after sometime getting error 500, Maximum concurrent users havereached.We have been told by our software provider that theconnection problem lies with the ADO components whichcommunicating with the SQL server.We have been turning round and round, without any luck.Your help will be highly appreciated.Thanks and best regardsDaveLearning is a Never Ending process*** Sent via Developersdex http://www.developersdex.com ***Don't just participate in USENET...get rewarded for it!
I am researching this and playing with using the syss.sysprocesses view and counting the dbid column. I would most likely want to store this information in a table with a date/time stamp because we really want to track our concurrent users during the day for awhile. Do you have any neat tricks in getting this done? Is there a DMV or Information_Schema view that could be used to accomplish this task? I found the following code on the internet:
SELECT DB_NAME(dbid) AS DBName, COUNT(dbid) AS NumberOfConnections, loginame AS LoginName, nt_domain AS NT_Domain, nt_username AS NT_UserName, hostname AS HostName FROM sys.sysprocesses
I'm trying to do Sharepoint DR with Log Shipping and every thing configured except one thing which is switch the WSS_Content (Standby /Read-Only) DB to be ready and Write.
I tried from
GUI or ALTER DATABASE [WSS_Content] SET READ_WRITE WITH NO_WAIT
I have two database files, one .mdf and one .ndf. The creator of these files has marked them readonly. I want to "attach" these files to a new database, but cannot do so because they are read-only. I get this message:
Server: Msg 3415, Level 16, State 2, Line 1 Database 'TestSprintLD2' is read-only or has read-only files and must be made writable before it can be upgraded.
What command(s) are needed to make these files read_write?
I have a query that runs for 10 sec on one database( A) and 5 min on another database(B) even though two database have identical scheam, tables, index and statistics..
I ran a profiler and got the below information CPU READ Write Database A: 92051 711956 8774 Database B: 91812 7621589 315822
A query runs on database has a significant larger read and write.. I don;t understand why this is happening? even though these two database have the same structure?? it has the same execution plan as well..
Hi, we're trying to read from a table and write back to the same table and are having a lot of trouble with blocking. What could we do to prevent our application from hanging due to blocking of this type?
Hi .. I want to Write in files or read from files for example i have My_File.txt . i need a syntax and i want to call this syntax in my Store procedure and this syntax write forexample " Hello Word " in My_File.txt . and i want another syntax that read from My_File.txt forexample "Word" from My_File.txt . what are those syntaxes do that ??
We currently run sql 2005 server and also sql express in our dev environments. We use sql express as an offline store (smart client). We have a similar/exact schema on the sql 2005 server and also the express.
We use the auto attach feature to connect to the express version of the database. Both the developer machines and the one that is running the sql 2005 server have exactly the same hardware configuration. The only difference may be that the server box is not running the VS.Net environment. The disk space etc is pretty much the same. Actually we run another database server(DB2) on the 2005 server machine.
We have observed that sql express is much slower and queries execute much slower aswell. For example, this may not be a totally scientific way of checking but a long running query on the server took only 2 minutes while on express it took longer than 9 minutes. The schema and data etc are the same.
Is there something we need to look into as far as read write speed/performance goes ?
I am using a Script Component and I have a Read/Write Variable varStatusCase (as assigned in the Custom Properties of my Script Component). I used this inside my script to get a specific value. However, when I ran it I get this error:
The collection of variables locked for read and write access is not available outside of PostExecute.
Okay, maybe I'm getting ahead of myself. Using SQL Server Express, VWD and .net 2.0 I've figured out how to drop a Table Column Constraint or Default Value/Binding and then Create it again using a stored procedure. What I can't figure out is how to retrieve that column's constraint value and write it to, say a label, in an aspx page, simply for reference. Is it possible? In this case the Data Type of the column is money. I'm using it to perform a calculation to a column with a value that the user inserts into another column. (Column1(user input) minus Column2(with Default Value) = Column3(Difference). I just want to read Column2's Default Value for reference so I know whether to change it or not.
Hi, I was reading that many of these high traffic websites actually have 2 databases, 1 database is used ONLY for reads, while the other is for writes.
How does one go about creating such a setup? How does the database where writes are allowed replicated the data to the read only database server?
Hi,I would like to use database locking mechanism to control access to anexternal resource (like file system).What I need is1. an exclusive (write) lock conflicting with any access to theresource (both for read and write)2. non-exlusive (read) lock conflicting with writes onlyHow this could be done?I'd appreciate any reply.Vadim
