Cannot fetch a row using a bookmark from OLE DB provider (Msg 7333, Level 16, State 2)

Linked Server Msg 7333

If you are getting this error and are trying to resolve it. Let me give you a little background information. A bookmark in this error is a left over from SQL Server 2005 SP1 and earlier. Bookmarks after 2005 SP1 is really a referred to as a key lookup, not to be confused with primary/foreign keys. From now on I am going to refer to bookmarks as key lookups so we are uniform and using the modern terminology.

Key lookups are objects within a query that refer to a data page (where the data is actually stored in the database) from a non-clustered index.

When SQL Server is executing DML (Insert, Update, Delete) against a linked server successfully for days, months, or even years and then fails with this error:

 Cannot fetch a row using a bookmark from OLE DB provider (Msg 7333, Level 16, State 2)

Something in the query execution plan is wrong. So far I have only run into this problem using linked servers and it probably has to do with resource management within SQL Server. Perhaps someone could elaborate on this that has more experience than I. But within the query’s execution plan, SQL Server decides to switch to a different index to run the query. The query then fails because it is using an index that is lacking information to complete the request.

Resolution

Ultimately, you have to do the following:

  1. Look at your where criteria in your query that is dependent on the linked server.
  2. Review indices on the table, that the where criteria is referring to.
  3. Is your one of your criteria covered by more than one index?

If you answered yes to number 3, there is a good chance that the behavior I am describing is actually causing your problem.

To diagnose this, disable one of the indexes  that is in question.

NOTE: Never disable the clustered index, you will prevent data access to the table.

Run the query again, and it should work, if not rebuild the disabled index to bring it back online and then disable the other index. If the query works you are in business. Talk with your database administrator, developer, or vendor of the application to come up with a good solution. But this will temporarily get your query to work.

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SQL Server Reporting Services ~ MultiValued Parameters

This is a really good article on multivalued parameters in a stored procedure. Very good read for SQL Server Reporting Services.

Tech Updates

In SSRS reports we can have multi valued paremeters, which means we can select multiple values for that parameter and based on all those selected values result in the report is shown. We can write the SQL query to pass those parameter’s values and populate the data set, but sometimes it is required or to optimize the performance we need to use the stored procedure instead of direct sql query. This stored procedure will be taking the report paremeter as input and returing the result set to populate the data set.

In case of sql query as well as stored procedure, all selected values of the multi-value parameter will be passed as ‘,’ (comma) separated. So we should use IN clause in WHERE to impose the desired condition.

Problem: If we use stored procedure passing an input parameter which is multi-value parameter, SSRS will take all those selected multiple values…

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SQL Server Error 823 Troubleshooting and Resolution

SQL Server Error 823

If you are getting this error, chances are you are having a hardware failure on your server, or perhaps someone deleted one of the database files.

Assuming you took care of that situation:

Do not Detach the Database

The very easy fix to do is to simply restore the database using your backups. But if you don’t have a good set of backups, Paul Randal ( he and his wife Kim, are SQL GODS) has a great set of steps to try in his article here.

Here is the short story of how to get your database up and running if your transaction log was damaged.

Error 823 Resolution

Switch the database into the emergency/single-user mode:

alter database <dbname> set emergency;
go
alter database <dbname> set single_user;
go
dbcc checkdb(‘<dbname>’,REPAIR_ALLOW_DATA_LOSS) with all_errormsgs, no_infomsgs;
go
alter database <dbname> set multi_user;
go
alter database <dbname> set online;
go

The main thing to realize here is that if the transaction log is damaged or missing that the transactions are not going to be found in the transaction log. You are going to lose any active transactions that have not been commited to the database. The real area of interest is the REPAIR_ALLOW_DATA_LOSS. This particular arguement allows you to recreate the transaction log. Do not take this command lightly as it will lose data, so please use it only as a last resort.

 

DBA Test/Development Server Best Practices

These are things I learned from a hardware failure of a test server (you might also call it a staging area). So what’s the big deal? Developers should have all their code checked into source control and nothing critical should be on there right?

Sadly no. These are things you should do on your test server to limit your exposure as a DBA.

1. Treat the server as a production server. This includes transaction log backups, backups of user accounts, SSIS, SSRS, SQL Agent jobs, and Windows Tasks.

2. Trust, but verify. Trust the developers to be following best practices, after all your job is to make the company money and so is theirs. Periodically issue correspondence with the developers to verify that nothing is running in a production manner.

3. Get a good snapshot/system image from time to time. If someone or something destroys your server, you have something to fall back upon. This is especially true when developers are creating lots of dependencies in their code to OS level libraries.

Monitoring SQL Server with Profiler ~ 5 Things to Avoid

SQL Profiler

Everyone loves Profiler and for good reason, it provides you with good data to help you make your SQL Server run even better. To quote FDR, “great power involves great responsibility.” Here is a brief list of things to avoid.

Run Profiler on the same server as SQL Server.

This adds too much overhead to the server, please don’t do it, EVER! Ideally, run it on a test server that has some good system resources to be able to capture and analyse all that data.

Select too many events to trace.

For example, selecting Batch Begin and Batch Completed. Choose only what you need.

Don’t filter the results.

Filtering saves you time crawling through the results and saves SQL Server time. This falls back on number 3, choose only what you need.

Don’t join the Performance Monitoring data with Profiler data.

Why chase down a problem, that is not the real cause of your slow server? While you may see a small performance boost on the server, you may be missing the elephant in the room.

SQL Server String PadLeft

I think this comes up a lot in day to day operations. Needing to pad the left hand side of a char/varchar field. T0 address this I made a handy dandy function that works similar to the padleft string function in .Net. There is a caveat to this code, if string length also sets the max length of string being returned. Below is the code, please test it for your application before putting it into production to make sure it has the behaviour that you need.

CREATE FUNCTION [dbo].[PadLeft](
    @StringLength INT,
@String VARCHAR(1000),
@PadChar CHAR(1)
)
RETURNS VARCHAR(1000)
AS
BEGIN
    DECLARE @Result VARCHAR(1000)
    DECLARE @PadLength INT;
    SET @PadLength = @StringLength LEN(@String)
    IF @PadLength <= 0
    BEGIN
        SET @Result =LEFT(@string,@StringLength)
    END
    ELSE
    BEGIN
        SET @Result =REPLICATE(@PadChar,@PadLength)+ @String
     END
    RETURN @Result
END

SQL Server Coalesce

Coalesce is one of those old functions that has been around for a very long time and lost some of it’s lime light. It is good for a number of things but it’s VERY important to know how it behaves.

Overview

So coalesce takes any two or more parameters and takes the first parameter which IS NOT NULL and returns that value. For example:

SELECT COALESCE(null,’  ‘, ‘value’);

This would return the second argument, ‘ ‘, not the value ‘value’. You need to be very careful with this! Sometimes programmers don’t recognize the difference between null and empty values. If that is you, I have a very good article discussing null values in SQL Server, listed below:

SQL Server Null Values ~ Into the Void (pun intended)