Skip to main content

The trouble with DBCC INPUTBUFFER()

DBCC INPUTBUFFER() is a very handy and easy to remember Database Console Command to show what SQL a specific user (mapped to a SPID) is executing. BUT it only returns a maximum of 255 characters which is often not enough to show the full command being executed.

There are a couple of solutions to this, thankfully. First, however, we need to know which users are currently logged in and their associated SPID (Server Process Identifier). To do this we use the trusty system stored procedure sp_who2:

EXEC sp_who2

Click to enlarge

If we put the SPID we are interested in into:


It returns the command being executed:

Click to enlarge

All well and good, but we can use this piece of code to return the full contents of the buffer:

USE master


SELECT @Handle = sql_handle
FROM sysprocesses
WHERE spid = 54

FROM ::fn_get_sql(@Handle)

Click to enlarge

I have happily been using the above script for years now, but wait there's a problem - ::fn_get_sql is marked as deprecated and though still currently available will be removed from future versions of SQL Server. Therefore we are being encouraged to use the Dynamic Management Function sys.dm_exec_sql_text() to return the text of commands. In the example below I have used sys.dm_exec_requests combined with the aforementioned function to return the contents of the buffer:

SET @spid = 54

SELECT r.session_id SPID
       ,DB_NAME(database_id) 'DBName'
FROM sys.dm_exec_requests r
CROSS APPLY sys.dm_exec_sql_text(r.sql_handle) t
WHERE r.session_id = @spid;

Click to enlarge

This is now my default way of dealing with this situation especially as we have some useful extra columns, however, remembering this (let alone typing it every time I need it) can be a nuisance so I have created a "snippet" from it - a new feature of SQL Server Management Studio 2012 details of which will follow in another posting. Previous to this I used snippets with the aid of SSMS Tools Pack which was free prior to the 2012 version but probably still worth buying if you like the other features it provides.

BTW, have you ever wondered what the double colon :: was before the function name? It is one of the peculiarities of SQL server and is only used in a few instances, more details of which can be found at Karen Delaney's blog.

This piece of code is ideal for a Snippet.


  1. Nice Article !
    This is my pleasure to read your article.
    Really this will help to people of SQL Server Community.

    I have also prepared one article about, Get last executed statement of lead blocker query using SQL Server DBCC Inputbuffer
    You can also visit my article, your comments and reviews are most welcome.


Post a Comment

Popular posts from this blog

How to move the Microsoft Assessment and Planning Toolkit (MAP) database to a different drive

The Microsoft Assessment and Planning Toolkit (MAP) is a very useful tool for scanning your network to find instances of SQL Server plus all manner of detailed information about the installed product, OS and hardware it sits on.

<Click image to enbiggen>
There is an issue with it the database it uses to store the data it collects, however. Assuming you don't have an instance called MAPS on your server, the product will install using LocalDB (a cut down version of SQL Server Express) and puts the databases on your C: drive. If you then scan a large network you could easily expand the database to 10GB which may cause issues on a server when that drive is often one of the smallest. However, there is a simple solution: connect to LocalDB using Management Studio, detach the databases, move to a different drive, set permissions on the new location if required and reattach the database. How do you connect to LocalDB? Here you go:

Connect to (localdb)\MAPTOOLKIT

The databases I move…

Generate scripts to attach multiple databases

There is a handy little "by product", if you like, when running queries which means you can quickly generate scripts to do different things. Below is an example of generating multiple "attach" commands that you can copy from the results pane into the main SSMS window for execution. I have found this very handy in the past:

SELECT 'CREATE DATABASE ['+name+'] ON ( FILENAME = N''F:\MSSQL\Data\'+name+'.mdf'' ), ( FILENAME = N''E:\MSSQL\Log\'+name+'_log.ldf'' )  FOR ATTACH GO ' FROMmaster.dbo.sysdatabases WHEREnamenotin('master','msdb','model','tempdb')

The Purge SQL Agent Job for MDW takes a long time to complete

I use the dbWarden alerts to inform me if a SQL job is taking longer to complete than normal and I got one this morning:
I noticed by looking at the history this purge job was gradually taking longer and longer to complete each day since I installed it again (see mylast post on this):
RunDate RunTime Duration ExecutionStatus JobName 04/10/2013 02:00:01 00:00:45 Succeded mdw_purge_data_[MDW] 05/10/2013 02:00:00 00:13:27 Succeded mdw_purge_data_[MDW] 06/10/2013 02:00:00 00:17:03 Succeded mdw_purge_data_[MDW] 07/10/2013 02:00:01