SQL Server 2005 Hanging - Selecting Uncommitted Data
Dec 5, 2006
We have found an issue with using MSS 2005 with odbc connections, some of
our code inserts data, then reselects the data back with a select using a
different handle. This hasn't caused any issues before but in one customer
this causes a lock up. The timeout error doesn't occur as you would expect
if trying to select data that is uncommitted by another user.
Although obviously we could re-code to avoid selecting uncommitted rows, can
anyone tell me why this works sometimes but not others. Some kind of
setting in MSS that we're unaware of maybe. The code works ok on other MSS
2005 & MSS 2000 servers and oracle & sqlbase.
Hi,I recently installed SQL Server 2005 Enterprise Edition (9.0.1399) andI have problems on queries concerning system file manipulation...For example, when I try to increase the Log File of MSDB database :ALTER DATABASE msdbMODIFY FILE(NAME = 'MSDBLog',SIZE = 50MB)This query never terminates...All SQL queries for database creation never terminateCREATE DATABASE EASYSHAREON PRIMARY(NAME = EASYSHAREData,FILENAME = 'D:AQSACOMDATAEasyshareEasyshareData.mdf',SIZE = 200MB,MAXSIZE = 1000MB,FILEGROWTH = 100MB)LOG ON(NAME = EASYSHARELog,FILENAME = 'E:AQSALOGEasyshareEasyshareLog.ldf',SIZE = 100MB,MAXSIZE = 300MB,FILEGROWTH = 50MB)Would someone have an idea of what happens...I'm running on Windows 2000 Server...ThanksPatrick
It appears that every 5 or so days, my transactional replication is hanging. I see that I have a couple thousand undistributed commands and this number keeps growing. It forces me to generate a snapshot in order to sync up. When generating the snapshot, I will get frequent messages like "waiting for a response from server...". So I will keep stopping and starting syncronization. Eventually the snapshot will go out, with a delay after generation.
1. In this topichttp://groups.google.com/group/comp...b21516252b65e7c,someone wrote: "I've implemented SET TRANSACTION ISOLATION LEVEL READUNCOMMITTED at the beginningof a number of stored procedures and, then SET TRANSACTION ISOLATIONLEVEL READCOMMITTED at the end to minimize the disruption to the application.".My question is, do you really need to set READ COMMITTED at the end ofstored procedure? What scope does that command affect?2. Could someone write some real world example where i should neverread uncommitted data... i'm having trouble understanding when ishould and when i should not use it.
Hi Sql gurus :))I've got a question that I couldn't find a satisfying answer on the net.What is the difference between:1) running sql query (select from sth with nolock) with no transaction2) running sql query (select from sth) withing a TransactionScope with option Read Uncommitted dataBasically, both should do the same work. However is anyone aware of any potential problems using any of both approaches ?We use 1) to improve our web application scalability since the system works in such a way that any selects and updates on that table (sth) do not interfere with one another.However, updates are done in a TransactionScope. And when having simultaneous select with nolock and update in a Transaction scope (the select statement has a where clause and returns records that are not updated by the update statement). However sometimes ( we still cannot figure it out when) the select statement returns some records twice.For example, the select should return 1000 records , but (sometimes) it returns 1002 records ( the extra 2 records are copies of some of the original 1000 records).Removing the nolock, makes the problem does not appear - but i want to be 100% sure that nolock is our troublemaker. And if it is - why ?We also have a problem that this particular nolock select sometimes return even less records than it should.I know it sounds impossible but it happens.So anyone who has experience with select with nolock, please share :)Thanks in advance, Yani
I'm running a DTS package on SQL Server. The source is MS Access and thetarget is Oracle.On a "Drop Table" command the process just hangs. There are no foreign keys onthe table. Several tables have already been processed successfully by thistime.I think I've ruled out corruption by dropping and recreating the targetdatabase on Oracle.Any ideas?M Man
In my control flow, I have a container which contains an Execute SQL Task, and then upon success, a Data Flow Task. The SQL Task truncates my datamart table. In the data flow task, I execute a stored procedure (through a variable) that populates that same datamart table. I can execute the stored procedure's select statement in Management Studio with no problems in about ten seconds. However, in the SSIS package, the SQL task completes successfully, and then it hangs indefinitely on the data flow step. In the Data Flow tab, none of the boxes are even turning yellow. Why won't it complete? When I move the Exec SQL Task to another container, the package executes fine, but it should be in the Load Phase container.
I have three tables that are joined together to retrieve a piece of data.Table One has the columns pid1(PK), idTable Two has the columns pid1, qid1, idTable three has columns qid1, question, answerHere is my sql statement:SELECT Table1.pid1, Table2.qid1, Table3.Question FROM Table1 JOIN Table2 ON Table1.pid1=Table2.pid1 JOIN Table3 ON Table2.qid1=Table3.qid1 WHERE Table1.pid=...(N)I put an elipsis because I'm stuck on how to proceed from here. See I need to randomly select a value from column pid1 in table1 then use this value to replace N in the sql statement, then have the statement run and randomly return exactly one piece of data instead.Is this possible? How can you randomly get one piece of data from joining three table without a WHERE CLAUSE.
Im just curious how i would take multiple columns from multiple tables.... would it be something like this ??? table: Products COLUMNS ProductName, ProductID table: Categorys COLUMNS CategoryName, CategoryID,ProductID SELECT Products.ProductName, Categorys.CategoryName,Products.ProductID,Categorys.CategoryID,Categorys.ProductID FROM Categorys, Tables WHERE Products.ProductID = Categorys.ProductID
I have just upgraded to SQL Server 2005 from SQL Server 2000.In Microsoft SQL Server Management Studio, when I click on databaseproperties, I receive the following error:-Cannot resolve the collation conflict between"Latin1_General_CI_AS"and "SQL_Latin1_General_CP1_CI_AS" in the equal to operation.(Microsoft SQL Server, Error: 468)Some reference suggest that I can change the database collation byclicking database properties!What can I do?
I have a problem with a process hanging my SQL server machine and the only thing that can fix it is to reboot the machine. The environment is SQL Server 7, NT sp5, dual processor 500MHZ, 1 gig Ram. The applications are run through MTS written in VB all executing stored procedures. The symptoms are that the process hangs with an open transaction and it can be seen through DBCC OPENTRAN. It can also be seen in MTS on the Transaction List screen and shows as Aborting. It seems to get stuck in that state. The Kill command does not work on the process either. I have tried one fixs that I thought may be causing the error by setting the Max Degree of Paralelism in sp_configure to 1 but that does not fix the problem.
Has anyone seen this and/or have any ideas on how to fix/repair the problem.
One of my clients runs a report using Access retrieving data from SQL*server. Recently I often encounter a problem which makes the server hang. The error messages are something like this, can somebody help?
SqlDumpExceptionHandler: Process 42 generated fatal exception c0000005 EXCEPTION_ACCESS_VIOLATION. SQL Server is terminating this process. Error: 0, Severity: 19, State: 0 CImageHelper::GetSym Error - The specified module could not be found Stack Dump being sent to H:MSSQL7logSQL00158.dmp
Can anyone suggest what might be causing SQL Server 6.5 to hang? The following messages were in the error log just before, but Books Online is not much help:
2000/08/21 10:35:20.90 ods Error : 17805, Severity: 18, State: 0 2000/08/21 10:35:20.90 ods Invalid buffer received from client. 2000/08/21 10:35:20.90 spid142 Process 142 entered sequencer without owning dataserver semaphore
there are then many messages like this one: 2000/08/21 10:36:21.06 ods Error : 17824, Severity: 10, State: 0 2000/08/21 10:36:21.06 ods Unable to write to ListenOn connection '.pipesqlquery', loginname 'E04180', hostname 'N90459'. 2000/08/21 10:36:21.06 ods OS Error : 109, The pipe has been ended.
and finally many more messages like this: 2000/08/21 10:51:20.75 ods Unable to connect. The maximum number of '750' configured user connections are already connected. System Administrator can configure to a higher value with sp_configure.
I don't think that simply increasing the number of user connections will help, but if anyone can throw some light on the cause of the first message I would be grateful.
Hi,Periodically I run some very complex queries or stored procedures that"hang", and the bigger problem is that it locks up all of the databaseclients ie 50 users connecting to the db via a windows application.I never know when this is going to happen, but when it does it leavesall the users completely hung up.1. Can I avoid this?2. Is there a way to "clear" what I was doing so that I don't have torestart the SQL Server serive?thanks,
I have created some dynamic sql to check a temporary table that is created on the fly for any columns that do contain data. If they do the column name is added to a dynamic sql, if not they are excluded. This looks like:
If (select sum(Case when [Sat] is null then 0 else 1 end) from #TABLE) >= 1 begin set @OIL_BULK = @OIL_BULK + '[Sat]' +',' END However, I am currently running this on over 230 columns and large tables 1.3 mil rows and it is quite slow. How I can dynamically create a sql script that only selects the columns in the table where there is data in a speedier manner. Unfortunately it has to be on the fly because the temporary table is created on the fly.
I'm running 7.0 sp2,windows 2000, 1gig of ram, and a 933mhz cpu. Server has been very stable with no problems until I moved a 2gig table into the database. Query performance is excellent even table scans take less than 2 minutes. The problem is that once a table scan is performed on the table (I can't index for every possible query) the query finishes but the enterprise manager freezes on the server and users can no longer connect. I've set SQL server to have only 650 MB of ram and the rest is free, problem also existed when the memory was controlled entirely by SQL server.
My cache Hit Ratio was 97% and Cache flushes 0.0 (unfortunately these can't be checked when the problem exist because the box is frozen). I may have a concurrency issue but I'm not sure how to be positive. I don't want to just throw memory at the problem because I'm not sure the problem will be fixed.
I was wondering if anyone could provide me with some help, to do with a problem we are experiencing with SQL Server 7 and Windows NT 4.
We have a database that we have imported data into and are trying to build some indexes on one of the tables. THe database size is about 4GB and the table contains 21,000,000 records. When we try to build the indexes SQL server starts off OK, but after about five minutes all drive activity stops, the server stops responsing, and we need to reboot.
The machine has 2 P3 800 processers and 768Mb of RAM. NT is running on SP6 and SQL Server is running on SP3. We were initially running with 512 MB of RAM, but increased it because we thought the memory was a problem. The Server is not a dedicated SQL Server.
I have used performance monitor when running the query in SQL Analyser and have noted the following counters:
Total Server Memory
This starts off about 208000KB and creeps up to about 625000KB just before the server hangs.
Free Memory Available
This starts off high and is about 6MB just before the server hangs.
Page Reads Sec
Normally 370 and 410
Page Writes Sec
157
Buffer Cache hit Ratio
99.1
I have tried setting the SQL Server max memory option to about 600 MB, and also let SQL Server dynamically allocate it.
I am using SQL Server 6.5 (service pack 3) on an NT 4.0 (service pack 3). It is being used as the back-end database server for Solomon IV (accounting package from Solomon Software). The client machines eventually lock-up after limited activity. The first user to lock seems to do so when they issue a save, once they are locked all other users lock. In SQL activity log the processes has several tables locked. If this process is killed, the other users seem to free up. The only error message found in SQL errorlog is an ODS Unable to write to ListenOn "pipe.sqlquery". This message seems to have been occuring for some time though (prior to the lock-up problems).
The only thing (I`m aware of) that changed is many of the clients where put on a 100Mb LAN and the database was expanded from 1G to 2G because it ws almost full.
I haven't used the READ UNCOMMITTED transaction isolation levelbefore, and I was wondering if this would be an appropriate use:I have an ID table containing ID numbers that are randomly generatedand need to be unique. There is a stored procedure that potentiallygenerates thousands of these IDs in one execution and inserts theminto the ID table and various other tables. The basic idea is asfollows:Begin TransactionWhile not all IDs generated {GenID:@NewID = GenerateID()If @NewID exists in ID tableGOTO GenIDInsert into ID tableInsert into various other tables}Commit TransactionThe problem occurs when the stored procedure is being run by more thanone process concurrently. The check to see whether @NewID exists inthe ID table will block, waiting for the transaction in the otherprocess to commit.Would this be an appropriate place to use the READ UNCOMMITTEDisolation level to allow different executions of the stored procedureto see what the others are writing into the ID table before thetransactions finish? I only really care that the IDs generated areunique; they're not in sequence or anything like that. Has anyone hadexperience with anything similar?
Transaction means the actions user perform in a database, like create table, update, select. Is that correct? Can back up or restore be transactions?
I recently read the tool-kit book and encountered 'uncommitted transactions' many times, esp. in the chapter of 'Backup and Recovery'. For example, today I wanna backup my database by backuping a full database, then three hours later performing a differential backup, and five mins later do transaction log backup. Then I restore those backups following the same sequence. When I restore diferential backup and log backup, I have the option to use one of the three options:
Leave the database ready for use by rolling back the uncommitted transactions. Additional transaction logs cannot be restored. (RESTORE WITH RECOVERY)
Leave the database non-operational, and do not roll back the uncommitted transactions. Additional transaction logs can be restored. (RESTORE WITH NORECOVERY)
Leave the database in read-only mode. Undo uncommitted transactions, but save the undo actions in a standby file so that recovery effects can be reverted. (RESTORE WITH STANDBY)
In the definitions above, 'uncommitted transactions' are all mentioned.
I do not understand why uncommitted transaction happned during or before or after backup( in my opinion, all transactions should be committed before you doing backup)? Can you please give me an example?
The backup jobs on one of our sql servers started hanging. The job appears to be complete because the backups are on the disk but the job never completes when viewed in the activity manager. sqlmaint.exe had numerous instances running all night long but the job never completes.
sql server 2000 standard edition sp3a Windows server 2000
The jobs on this server have run successfully for well over a year and just recently they started hanging. We've done everything short of reboot the server. We've restarted the agent, shut down the sqlmaint.exe but alas nothing we do lets the job complete.
Other jobs that are not back up related are working as they should.
There is plenty of disk space.
Any ideas?
thanks in advance because we are lost as to the cause and resolution.
Hi all,Have a situation that my company has never run across before. Clientis running NT4 for the domain server, using terminal services 2000 andrunning an application with a SQL Server backend and they areexperiencing locking problems. Once one person gets locked out theneveryone trying to access that tables is also locked out as a result.It is not specific to a certain User, or module within theapplication. It's not a specific time of the day (like when a backupwould be running) and sometimes it's in the middle of the night whenthere are actually less Users on the system.We have 500 customers using this application. Most are using SQLServer backend, alot of the newer customers are using TerminalServices, and the number of Users is not accessive as compared to ourother customers. THe only difference is that I do not specificallyknow of another client with an NT4 Domain server in the mix.We actually switched to SQL Server as the recommended back end due tolocking issues using SQLBase because SQL Server is row locking andSQLBase is page locking. Since making this change we have stoppedseeing the locking for years until now. Is this a SQLServer issue orissue with the NT Domain server?Anyone have any ideas???ThanksA
Are there really any benefit on using Read Uncommitted Isolation Level or having a NOLOCK hints for retrieve queries when the default Isolation level just Read Committed (not using COM+). I'm confused why the Community Server uses this technique perhaps for perf issues but I couldn't see any reason why...
I have a weird intermittent issue with an enterprise version of SS2014. When clicking or right clicking around SSMS will lock up and display the 'SSMS is busy - waiting for an internal operation to complete'. It is only specific to the server as when I connect using my local SSMS this doesn't happen. This was happening both pre and post SP1 install.
I have soma ado.net code that inserts 7 parameters in a database ( a date, 6 integers). I also use a self incrementing ID but the date is set as primary key because for each series of 6 numbers of a certain date there may only be 1 entry. Moreover only 1 entry of 6 integers is possible for 2 days of the week, (tue and fr). I manage to insert a row of data in the database, where the date is set as smalldatetime and displays as follows: 1/05/2007 0:00:00 in the table. I want to retrieve the series of numbers for a certain date that has been entered (without taking in account the hours and seconds). A where clause seems to be needed but I don’t know the syntax or don’t find the right function I use the following code to insert the row :
and the following code to get the row back (to put in arraylist):
“SELECT C1, C2, C3, C4, C5, C6 FROM Series WHERE (LDate = Today())� WHERE LDate = '" + DateTime.Today.ToString() + "'"
Which is the correct syntax? Is there a better way to insert and select based on the date?
I don’t get any error messages and the code executes fine but I only get an empty datatable in my dataset (the table isn’t looped for rows I noticed while debugging). Today’s date is in the database but isn’t found by my tsql code I think.
Yesterday, we have had a sudden load in our SQL Server 2000 which resulted in several locks. There was not too much time to investigate as we had to rush. A team member had reviewed the processes in EM, Manegement, Current Activity. Looking for blocking processes and killed them.
She told me that as soon as the blocking SPID was killed, another one arose and she had to repeat the operation a dozen of time. When done, the server activity was back to normal. She noticed that more than half of the blocking processes showed that they executed the stored Proc "P_SearchProducts".
We don't own the server and the information on what had happened at that time (batches or resource intensive operations, etc.) is not available for now.
The team suggests that we set the Transaction Isolation Level to Read UNCOMMITTED for this SP. I would like to know better about locks before I go ahead.
P_SearchProducts returns 5 recordsets each one could contains from 1 to 200 rows. To achieve the results, it creates about 10 intermediate tables (SELECT ... INTO #TableX) these temp tables are then used progressively to arrive to the final results. Roughly the volume of these temp tables could be double than the final results. The developer who wrote this SP is not a guru in SQL, there is room for improvement. But here are my questions:
Q1. Could the series SELECT ... INTO #TableX in P_SearchProducts prevent or lock another connection from executing the same SP? If yes, under which conditions?
Q2. Let's assume that P_SearchProducts has a slow execution time. Could it prevent another connection from updating the Product table? And thus leading to a deadlock situation? Something like another transaction (by User2) has obtained lock on most of Product tables, except the Product table which were being slowly read by User1 executing P_SearchProducts. But User1 cannot read the other product tables b/c there are locks by User2.
Q3. If the contention issue was provoked by the slow execution time of many request to exec P_SearchProducts (let's assume there were suddenly 50 users on the web hitting the search product feature at the same time). Could the Read Uncommitted magically resolve the contention issue, providing we accept the consequences of the dirty read.
Sorry for the long post and thank you in advance for any help.
I am pretty new to SSIS. I am trying to create a package which can accept data in any of several formats. i.e. CSV, Excel, a SQL Server database/table and import the data into my destination database.
So far i've managed to get this working OK. However I am now TOTALLY stuck. I'm currently trying to just concentrate on the data sources being a CSV (using a Flat File Data Source) and/or an Excel Spreadsheet.
I can get the data in and to my destination using a UNION ALL component and mapping the data sources to it so long as both the CSV file and the Excel spreadsheet exist.
My problem is that I need my package to handle the possibility that only the CSV file might exist and there is no Excel spreadsheet. In which case i'd like the package to ignore the Excel datasource completely. Currently either of my data sources do not exist I get errors and the package terminates.
Is there any way in SSIS that I can check all my data sources to see which ones exist (i.e. are valid). If they exist I want to use them. If it doesn't exist i'd like to disgard it (without error - as long as there is a single datasource the package should run)
I've tried using the AcquireConnection method in a script task on each of my connections, hoping that it would error if the file/datasource did not exist. It doesn't though (in the case of an Excel datasource it just creates a empty excel file for me).
The only other option I can come up with are to have seperate packages depending on the type of data we want to import and then run a particular package depending on the format of the source data. This seems a bit long winded. I am pretty sure I must be able to do what I want to achieve but I can't work out how.
I'll be grateful to anyone who can send me any tips/hints/links on how I can achieve this.
I have a scenarios where if I execute select * from tbl it should display the all the records without waiting to release any lock. For example suppose I have one table called tbl and one session is updating one records and not committed yet and in other session if i execute select * from table I can see all the records, for that records it can show me older version. but my select statement should not wait to commit another session and also it should not show the modified data.
We have a stock code table with a description field and a brand field - when the data was entered, some of the records were entered with the brand field in the description field.
ie. Code Description Brand ABC1 BLANK DVD SONY ABC2 SONY BLANK DVD SONY
what I need to do is identify where the Brand is in the Description field ...
