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Archive for the ‘SQL DMV’ Category

SQL SERVER – Denali – DMV – sys.dm_os_volume_stats – Information about operating system volume

Posted in Technology, SQL Server, SQL, SQL Query, SQL Tips and Tricks, SQL Authority, SQLAuthority News, T SQL, SQL DMV, PostADay on September 30, 2011 | 4 Comments »

SQL Server Denali has many new interesting feature – one of the interesting feature is New DMVs.

This DMV returns information about the operating system volume (directory) on which the specified databases and files are stored. Here is the quick example I have created for the same.

SELECT DB_NAME(f.database_id) DatabaseName,
f.FILE_ID, size DBSize, file_system_type,
volume_mount_point, total_bytes, available_bytes
FROM sys.master_files AS f
CROSS APPLY sys.dm_os_volume_stats(f.database_id, f.FILE_ID);

Here is the screenshot of the same:

In the result set we can see the file system and volume database is mounted on as well database size.

Reference: Pinal Dave (http://blog.SQLAuthority.com)

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SQL SERVER – Denali – DMV Enhancement – sys.dm_exec_query_stats – New Columns

Posted in Technology, SQL Server, SQL, SQL Query, SQL Tips and Tricks, SQL Authority, Pinal Dave, T SQL, SQL Scripts, SQL DMV, PostADay on September 28, 2011 | 4 Comments »

SQL Server version next Denali has lots of enhancements. Some of the enhancements are just game changing and overcomes needs of more coding to do the same thing.

Similar function DMV is sys.dm_exec_query_stats. There are four new columns added to this DMV. I have often used this DMV to check recently ran query, their execution plan by joining more DMVs to it. However, there was also need of knowing how many rows my queries have returned.

This DMV is enhanced with four more queries.

total_rows – Total number of rows returned by query
last_rows – Number of the rows return by the last execution of the query
min_rows – Minimum numbers of the rows returned by the query since it is compiled
max_rows – Maximum numbers of the rows returned by the query since it is compiled

Here see the quick example of the columns:

SELECT qs.execution_count,
qs.total_rows, qs.last_rows, qs.min_rows, qs.max_rows,
SUBSTRING(qt.TEXT,qs.statement_start_offset/2 +1,
(CASE WHEN qs.statement_end_offset = -1
THEN LEN(CONVERT(NVARCHAR(MAX), qt.TEXT)) * 2
ELSE qs.statement_end_offset END -
qs.statement_start_offset
)/2
) AS query_text
FROM sys.dm_exec_query_stats AS qs
CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) AS qt
ORDER BY qs.execution_count DESC;

If you run above query it will give us different result based on your server’s workload.

You can see that the above result set – it displays how many time query has executed and how new columns (total_rows, last_rows, min_rows and max_rows) returns result based on the query.

Now here is the question back to you – if you have downloaded Denali and installed it, I would like to see you use this new column and come up with some more creative usage.

Reference: Pinal Dave (http://blog.SQLAuthority.com)

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SQL SERVER – Author’s Book is Available in India and USA

Posted in Technology, SQL Server, SQL, SQL Query, Database, SQL Tips and Tricks, SQL Authority, Pinal Dave, T SQL, SQL Scripts, SQLAuthority Book Review, SQL DMV, SQLServer, PostADay, Joes 2 Pros on August 25, 2011 | 4 Comments »

I am feeling very good to write this short blog post. My book is now officially available on in India and USA.

In India you can get it from Flipkart - http://bit.ly/pinalbook

In USA you can get it from Amazon – http://amzn.to/pb49jq

This book is just like this blog and contains all the complex subject in very simple manner. I am confident that you will for sure like this book if you like this blog.

Here is quick video shot by my wife when I was reading my own book. See the original post to see the video.

Here is quick secret for you – there is big surprise in September for all those who own this book.

Reference:  Pinal Dave (http://blog.SQLAuthority.com)

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SQL SERVER – Find Details for Statistics of Whole Database – DMV – T-SQL Script

Posted in Pinal Dave, PostADay, SQL, SQL Authority, SQL DMV, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology, tagged , on June 29, 2011 | 12 Comments »

I was recently asked is there a single script which can provide all the necessary details about statistics for any database. This question made me write following script. I was initially planning to use sp_helpstats command but I remembered that this is marked to be deprecated in future. Again, using DMV is the right thing to do moving forward. I quickly wrote following script which gives a lot more information than sp_helpstats.

USE AdventureWorks
GO
SELECT DISTINCT
OBJECT_NAME(s.[object_id]) AS TableName,
c.name AS ColumnName,
s.name AS StatName,
s.auto_created,
s.user_created,
s.no_recompute,
s.[object_id],
s.stats_id,
sc.stats_column_id,
sc.column_id,
STATS_DATE(s.[object_id], s.stats_id) AS LastUpdated
FROM sys.stats s JOIN sys.stats_columns sc ON sc.[object_id] = s.[object_id] AND sc.stats_id = s.stats_id
JOIN sys.columns c ON c.[object_id] = sc.[object_id] AND c.column_id = sc.column_id
JOIN sys.partitions par ON par.[object_id] = s.[object_id]
JOIN sys.objects obj ON par.[object_id] = obj.[object_id]
WHERE OBJECTPROPERTY(s.OBJECT_ID,'IsUserTable') = 1
AND (s.auto_created = 1 OR s.user_created = 1);

If you have better script to retrieve information about statistics, please share here and I will publish it with due credit.

Update: Read follow up excellent blog post by Jason Brimhall.

Reference: Pinal Dave (http://blog.SQLAuthority.com)

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SQL SERVER – Pending IO request in SQL Server – DMV

Posted in PostADay, SQL, SQL Authority, SQL DMV, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology on March 13, 2011 | 4 Comments »

I received following question:

“How do we know how many pending IO requests are there for database files (.mdf, .ldf) individually?”

Very interesting question and indeed answer is very interesting as well.

Here is the quick script which I use to find the same. It has to be run in the context of the database for which you want to know pending IO statistics.

USE DATABASE
GO
SELECT vfs.database_id, df.name, df.physical_name
,vfs.FILE_ID, ior.io_pending
FROM sys.dm_io_pending_io_requests ior
INNER JOIN sys.dm_io_virtual_file_stats (DB_ID(), NULL) vfs
ON (vfs.file_handle = ior.io_handle)
INNER JOIN sys.database_files df ON (df.FILE_ID = vfs.FILE_ID)

I keep this script handy as it works like magic every time. If you use any other script please post here and I will post it with due credit.

Reference: Pinal Dave (http://blog.SQLAuthority.com)

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