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  • SQL SERVER – Weekly Series – Memory Lane – #007

    - by pinaldave
    Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2006 Find Stored Procedure Related to Table in Database – Search in All Stored Procedure In 2006 I wrote a small script which will help user  find all the Stored Procedures (SP) which are related to one or more specific tables. This was quite a popular script however, in SQL Server 2012 the same can be achieved using new DMV sys.sql-expression_dependencies. I recently blogged about it over Find Referenced or Referencing Object in SQL Server using sys.sql_expression_dependencies. 2007 SQL SERVER – Versions, CodeNames, Year of Release 1993 – SQL Server 4.21 for Windows NT 1995 – SQL Server 6.0, codenamed SQL95 1996 – SQL Server 6.5, codenamed Hydra 1999 – SQL Server 7.0, codenamed Sphinx 1999 – SQL Server 7.0 OLAP, codenamed Plato 2000 – SQL Server 2000 32-bit, codenamed Shiloh (version 8.0) 2003 – SQL Server 2000 64-bit, codenamed Liberty 2005 – SQL Server 2005, codenamed Yukon (version 9.0) 2008 – SQL Server 2008, codenamed Katmai (version 10.0) 2011 – SQL Server 2008, codenamed Denali (version 11.0) Search String in Stored Procedure Searching sting in the stored procedure is one of the most frequent task developer do. They might be searching for a table, view or any other details. I have written a script to do the same in SQL Server 2000 and SQL Server 2005. This is worth bookmarking blog post. There is an alternative way to do the same as well here is the example. 2008 SQL SERVER – Refresh Database Using T-SQL NO! Some of the questions have a single answer NO! You may want to read the question in the original blog post. I had a great time saying No! SQL SERVER – Delete Backup History – Cleanup Backup History SQL Server stores history of all the taken backup forever. History of all the backup is stored in the msdb database. Many times older history is no more required. Following Stored Procedure can be executed with a parameter which takes days of history to keep. In the following example 30 is passed to keep a history of month. 2009 Stored Procedure are Compiled on First Run – SP taking Longer to Run First Time Is stored procedure pre-compiled? Why the Stored Procedure takes a long time to run for the first time?  This is a very common questions often discussed by developers and DBAs. There is an absolutely definite answer but the question has been discussed forever. There is a misconception that stored procedures are pre-compiled. They are not pre-compiled, but compiled only during the first run. For every subsequent runs, it is for sure pre-compiled. Read the entire article for example and demonstration. Removing Key Lookup – Seek Predicate – Predicate – An Interesting Observation Related to Datatypes This is one of the most important performance tuning lesson on my blog. I suggest this weekend you spend time reading them and let me know what you think about the concepts which I have demonstrated in the four part series. Part 1 | Part 2 | Part 3 | Part 4 Seek Predicate is the operation that describes the b-tree portion of the Seek. Predicate is the operation that describes the additional filter using non-key columns. Based on the description, it is very clear that Seek Predicate is better than Predicate as it searches indexes whereas in Predicate, the search is on non-key columns – which implies that the search is on the data in page files itself. Policy Based Management – Create, Evaluate and Fix Policies This article will cover the most spectacular feature of SQL Server – Policy-based management and how the configuration of SQL Server with policy-based management architecture can make a powerful difference. Policy based management is loaded with several advantages. It can help you implement various policies for reliable configuration of the system. It also provides additional administration assistance to DBAs and helps them effortlessly manage various tasks of SQL Server across the enterprise. 2010 Recycle Error Log – Create New Log file without Server Restart Once I observed a DBA to restaring the SQL Server when he needed new error log file. This was funny and sad both at the same time. There is no need to restart the server to create a new log file or recycle the log file. You can run sp_cycle_errorlog and achieve the same result. Get Database Backup History for a Single Database Simple but effective script! Reducing CXPACKET Wait Stats for High Transactional Database The subject is very complex and I have done my best to simplify the concept. In simpler words, when a parallel operation is created for SQL Query, there are multiple threads for a single query. Each query deals with a different set of the data (or rows). Due to some reasons, one or more of the threads lag behind, creating the CXPACKET Wait Stat. Threads which came first have to wait for the slower thread to finish. The Wait by a specific completed thread is called CXPACKET Wait Stat. Information Related to DATETIME and DATETIME2 There are quite a lot of confusion with DATETIME and DATETIME2. DATETIME2 is also one of the underutilized datatype of SQL Server.  In this blog post I have written a follow up of the my earlier datetime series where I clarify a few of the concepts related to datetime. Difference Between GETDATE and SYSDATETIME Difference Between DATETIME and DATETIME2 – WITH GETDATE Difference Between DATETIME and DATETIME2 2011 Introduction to CUME_DIST – Analytic Functions Introduced in SQL Server 2012 SQL Server 2012 introduces new analytical function CUME_DIST(). This function provides cumulative distribution value. It will be very difficult to explain this in words so I will attempt small example to explain you this function. Instead of creating new table, I will be using AdventureWorks sample database as most of the developer uses that for experiment. Introduction to FIRST _VALUE and LAST_VALUE – Analytic Functions Introduced in SQL Server 2012 SQL Server 2012 introduces new analytical functions FIRST_VALUE() and LAST_VALUE(). This function returns first and last value from the list. It will be very difficult to explain this in words so I’d like to attempt to explain its function through a brief example. Instead of creating a new table, I will be using the AdventureWorks sample database as most developers use that for experiment purposes. OVER clause with FIRST _VALUE and LAST_VALUE – Analytic Functions Introduced in SQL Server 2012 – ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING “Don’t you think there is bug in your first example where FIRST_VALUE is remain same but the LAST_VALUE is changing every line. I think the LAST_VALUE should be the highest value in the windows or set of result.” Puzzle – Functions FIRST_VALUE and LAST_VALUE with OVER clause and ORDER BY You can see that row number 2, 3, 4, and 5 has same SalesOrderID = 43667. The FIRST_VALUE is 78 and LAST_VALUE is 77. Now if these function was working on maximum and minimum value they should have given answer as 77 and 80 respectively instead of 78 and 77. Also the value of FIRST_VALUE is greater than LAST_VALUE 77. Why? Explain in detail. Introduction to LEAD and LAG – Analytic Functions Introduced in SQL Server 2012 SQL Server 2012 introduces new analytical function LEAD() and LAG(). This functions accesses data from a subsequent row (for lead) and previous row (for lag) in the same result set without the use of a self-join . It will be very difficult to explain this in words so I will attempt small example to explain you this function. Instead of creating new table, I will be using AdventureWorks sample database as most of the developer uses that for experiment. A Real Story of Book Getting ‘Out of Stock’ to A 25% Discount Story Available Our book was out of stock in 48 hours of it was arrived in stock! We got call from the online store with a request for more copies within 12 hours. But we had printed only as many as we had sent them. There were no extra copies. We finally talked to the printer to get more copies. However, due to festivals and holidays the copies could not be shipped to the online retailer for two days. We knew for sure that they were going to be out of the book for 48 hours. This is the story of how we overcame that situation! Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • What command to use to unpack a .tar.gz file in Windows?

    - by Ivan
    I use to receive tar.gz files fromm colleagues but unpacking them with 7zip is not convenient as it unpacks a tar file from gz first while I usually seek to get the tar file contents (so I have to unpack the tar file explicitly next). I've tried adding tar -zxvf %P%N command to Total Commander button bar but it turned that tar -zxvf doesn't work but returns the following error (tried it in bare command prompt): tar: Cannot fork: Function not implemented tar: Error is not recoverable: exiting now I have got both GnuWin32 and cygwin installed, but I seek a solution that will work in Windows command line promt (and so will be callable from Totat Commander), not in cygwin command line promt.

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  • Watch videos from a remote computer on the LAN on ubuntu

    - by tapan
    I want to watch the videos on a friends computer on the LAN without having to download it. Both of us are running ubuntu. Now one way is to ssh to his computer, cd to the directory where the video is and run the falling command: cat video.avi | ssh me@mycomputer mplayer - This works. However the problem is that I cannot seek inside the video as in can't go forward or backward in it. Is there a method by which I can watch the videos and also seek in them ? I can install any software on his comp and my comp to aid this process. I have root level access on both computers. Any suggestions ?

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  • Having issues using fdisk and GParted with Lexar 64GB USB, but reading and writing is fine

    - by MetaDark
    I have recently bought a new 64GB Lexar USB with the long model name of LJDV10-64G-000-106, and I am having issues partitioning it. I am able to mount, read and write to the USB without any issues but whenever I try to partition it with GParted it doesn't show up in the dropdown. Also while using the command sudo fdisk -l I receive the error fdisk: unable to seek on /dev/sdc: Invalid argument. This is a brand new USB so I am not sure why I am having these issues, especially since the device is functioning perfectly with read/write. I have tried reformatting it on a windows machine but that does not seem to do anything. For those who want a visual my USB looks almost exactly like But 64GB rather than 8GB Edit: I have just ran GParted from the terminal and I am getting a similar error, but it may give more information on the issue. Could not determine physical sector size for /dev/sdc. Using the logical sector size (512). Invalid argument during seek for read on /dev/sdc Also clearing my USB with /dev/zero fails with the the message $ sudo dd if=/dev/zero of=/dev/sdc bs=1M dd: writing `/dev/sdc': No space left on device 1+0 records in 0+0 records out 0 bytes (0 B) copied, 0.00167254 s, 0.0 kB/s

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  • Restoring GRUB2 on Software RAID 0 after Windows 7 wiped it using LiveCD

    - by unknownthreat
    I have installed Ubuntu 10.10 on my system. However, I need to install Windows 7 back, and I expect that it would alter GRUB and it did. Right now, my partition on my Software RAID 0 looks like this: nvidia_acajefec1 is Ubuntu 10.10 and nvidia_acajefec3 is Windows 7. I've been following some guides around and I am always stuck at GRUB not able to detect the usual RAID content. I've tried running: sudo grub > root (hd0,0) GRUB complains it couldn't find my hard disk. So I tried: find (hd0,0) And it complains that it couldn't find anything. So I tried: find /boot/grub/stage1 It said "file not found". Here's the text from the console: ubuntu@ubuntu:~$ grub Probing devices to guess BIOS drives. This may take a long time. [ Minimal BASH-like line editing is supported. For the first word, TAB lists possible command completions. Anywhere else TAB lists the possible completions of a device/filename. ] grub> root (hd0,0) root (hd0,0) Error 21: Selected disk does not exist grub> find /boot/grub/stage1 find /boot/grub/stage1 Error 15: File not found Fortunately, I got one person suggesting that what I've been trying to do is for GRUB Legacy, not GRUB2. So I went to the suggested website, ** (http://grub.enbug.org/Grub2LiveCdInstallGuide) **try to look around, and try: ubuntu@ubuntu:~$ sudo fdisk -l Unable to seek on /dev/sda This is just the step 2 of the instruction in the http://grub.enbug.org/Grub2LiveCdInstallGuide and I cannot proceed because it cannot seek /dev/sda. However, ubuntu@ubuntu:~$ sudo dmraid -r /dev/sdb: nvidia, "nvidia_acajefec", stripe, ok, 488397166 sectors, data@ 0 /dev/sda: nvidia, "nvidia_acajefec", stripe, ok, 488397166 sectors, data@ 0 So what now? Do you have an idea for how to make fdisk see my RAID array on live cd (Ubuntu 10.10)? Honestly, I am lost, very lost in trying to restore GRUB2 on this software RAID 0 system right now.

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  • Restoring GRUB2 on Software RAID 0 using LiveCD after Windows 7 wiped it

    - by unknownthreat
    I have installed Ubuntu 10.10 on my system. However, I need to install Windows 7 back, and I expect that it would alter GRUB and it did. Right now, my partition on my Software RAID 0 looks like this: nvidia_acajefec1 is Ubuntu 10.10 and nvidia_acajefec3 is Windows 7. I've been following some guides around and I am always stuck at GRUB not able to detect the usual RAID content. I've tried running: sudo grub > root (hd0,0) GRUB complains it couldn't find my hard disk. So I tried: find (hd0,0) And it complains that it couldn't find anything. So I tried: find /boot/grub/stage1 It said "file not found". Here's the text from the console: ubuntu@ubuntu:~$ grub Probing devices to guess BIOS drives. This may take a long time. [ Minimal BASH-like line editing is supported. For the first word, TAB lists possible command completions. Anywhere else TAB lists the possible completions of a device/filename. ] grub> root (hd0,0) root (hd0,0) Error 21: Selected disk does not exist grub> find /boot/grub/stage1 find /boot/grub/stage1 Error 15: File not found Fortunately, I got one person suggesting that what I've been trying to do is for GRUB Legacy, not GRUB2. So I went to the suggested website, ** (http://grub.enbug.org/Grub2LiveCdInstallGuide) **try to look around, and try: ubuntu@ubuntu:~$ sudo fdisk -l Unable to seek on /dev/sda This is just the step 2 of the instruction in the http://grub.enbug.org/Grub2LiveCdInstallGuide and I cannot proceed because it cannot seek /dev/sda. However, ubuntu@ubuntu:~$ sudo dmraid -r /dev/sdb: nvidia, "nvidia_acajefec", stripe, ok, 488397166 sectors, data@ 0 /dev/sda: nvidia, "nvidia_acajefec", stripe, ok, 488397166 sectors, data@ 0 So what now? Do you have an idea for how to make fdisk see my RAID array on live cd (Ubuntu 10.10)? Honestly, I am lost, very lost in trying to restore GRUB2 on this software RAID 0 system right now.

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  • Calculating IOPS for a single HDD - what am I doing wrong?

    - by red888
    So I know there is no standardized way of calculating IOPS for a HDD, but from everything I have read it appears one of the most accurate formulas is the following: IOP/ms = + {rotational latency} + ({block size} / {data transfer rate}) Which is IOs per millisecond or what the book I've been reading calls "Disk Service Time". Also rotational latency is calculated as half of one rotation in milliseconds. This was taken from the EMC book "Information Storage and Management" -arguably a pretty reliable source right\wrong? Putting this formula into practice consider this Seagate data sheet. I am going to calculate IOPS for the ST3000DM001 model for a block size of 4kb: Seek Average (Write) = 9.5 -I'll measuring IOPS for writes Spindle speed = 7200rpm Average Data Rate = 156MB/s So my variables are: Seek Time = 9.5ms Rotational latency = (.5 / (7200rpm / 60)) = 0.004s = 4ms Data Rate = 156MB/s = (0.156MB/ms / 0.004MB) = 39 9.5ms + 4ms + 39 = IO/ms 52.5 1 / (52.5 * 0.001) = 19 IOPS 19 IOPS for this drive clearly is not right so what am I doing wrong?

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  • Would SSD drives benefit from a non-default allocation unit size?

    - by davebug
    The default allocation unit size recommended when formatting a drive in our current set-up is 4096 bytes. I understand the basics of the pros and cons of larger and smaller sizes (performance boost vs. space preservation) but it seems the benefits of a solid state drive (seek times massively lower than hard disks) may create a situation where a much smaller allocation size is not detrimental. Were this the case it would at least partially help to overcome the disadvantage of SSD (massively higher prices per GB). Is there a way to determine the 'cost' of smaller allocation sizes specifically related to seek times? Or are there any studies or articles recommending a change from the default based on this newer tech? (Assume the most average scattering of sizes program files, OS files, data, mp3s, text files, etc.)

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  • Troubleshooting Application Timeouts in SQL Server

    - by Tara Kizer
    I recently received the following email from a blog reader: "We are having an OLTP database instance, using SQL Server 2005 with little to moderate traffic (10-20 requests/min). There are also bulk imports that occur at regular intervals in this DB and the import duration ranges between 10secs to 1 min, depending on the data size. Intermittently (2-3 times in a week), we face an issue, where queries get timed out (default of 30 secs set in application). On analyzing, we found two stored procedures, having queries with multiple table joins inside them of taking a long time (5-10 mins) in getting executed, when ideally the execution duration ranges between 5-10 secs. Execution plan of the same displayed Clustered Index Scan happening instead of Clustered Index Seek. All required Indexes are found to be present and Index fragmentation is also minimal as we Rebuild Indexes regularly alongwith Updating Statistics. With no other alternate options occuring to us, we restarted SQL server and thereafter the performance was back on track. But sometimes it was still giving timeout errors for some hits and so we also restarted IIS and that stopped the problem as of now." Rather than respond directly to the blog reader, I thought it would be more interesting to share my thoughts on this issue in a blog. There are a few things that I can think of that could cause abnormal timeouts: Blocking Bad plan in cache Outdated statistics Hardware bottleneck To determine if blocking is the issue, we can easily run sp_who/sp_who2 or a query directly on sysprocesses (select * from master..sysprocesses where blocking <> 0).  If blocking is present and consistent, then you'll need to determine whether or not to kill the parent blocking process.  Killing a process will cause the transaction to rollback, so you need to proceed with caution.  Killing the parent blocking process is only a temporary solution, so you'll need to do more thorough analysis to figure out why the blocking was present.  You should look into missing indexes and perhaps consider changing the database's isolation level to READ_COMMITTED_SNAPSHOT. The blog reader mentions that the execution plan shows a clustered index scan when a clustered index seek is normal for the stored procedure.  A clustered index scan might have been chosen either because that is what is in cache already or because of out of date statistics.  The blog reader mentions that bulk imports occur at regular intervals, so outdated statistics is definitely something that could cause this issue.  The blog reader may need to update statistics after imports are done if the imports are changing a lot of data (greater than 10%).  If the statistics are good, then the query optimizer might have chosen to scan rather than seek in a previous execution because the scan was determined to be less costly due to the value of an input parameter.  If this parameter value is rare, then its execution plan in cache is what we call a bad plan.  You want the best plan in cache for the most frequent parameter values.  If a bad plan is a recurring problem on your system, then you should consider rewriting the stored procedure.  You might want to break up the code into multiple stored procedures so that each can have a different execution plan in cache. To remove a bad plan from cache, you can recompile the stored procedure.  An alternative method is to run DBCC FREEPROCACHE which drops the procedure cache.  It is better to recompile stored procedures rather than dropping the procedure cache as dropping the procedure cache affects all plans in cache rather than just the ones that were bad, so there will be a temporary performance penalty until the plans are loaded into cache again. To determine if there is a hardware bottleneck occurring such as slow I/O or high CPU utilization, you will need to run Performance Monitor on the database server.  Hopefully you already have a baseline of the server so you know what is normal and what is not.  Be on the lookout for I/O requests taking longer than 12 milliseconds and CPU utilization over 90%.  The servers that I support typically are under 30% CPU utilization, but your baseline could be higher and be within a normal range. If restarting the SQL Server service fixes the problem, then the problem was most likely due to blocking or a bad plan in the procedure cache.  Rather than restarting the SQL Server service, which causes downtime, the blog reader should instead analyze the above mentioned things.  Proceed with caution when restarting the SQL Server service as all transactions that have not completed will be rolled back at startup.  This crash recovery process could take longer than normal if there was a long-running transaction running when the service was stopped.  Until the crash recovery process is completed on the database, it is unavailable to your applications. If restarting IIS fixes the problem, then the problem might not have been inside SQL Server.  Prior to taking this step, you should do analysis of the above mentioned things. If you can think of other reasons why the blog reader is facing this issue a few times a week, I'd love to hear your thoughts via a blog comment.

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  • Joins in single-table queries

    - by Rob Farley
    Tables are only metadata. They don’t store data. I’ve written something about this before, but I want to take a viewpoint of this idea around the topic of joins, especially since it’s the topic for T-SQL Tuesday this month. Hosted this time by Sebastian Meine (@sqlity), who has a whole series on joins this month. Good for him – it’s a great topic. In that last post I discussed the fact that we write queries against tables, but that the engine turns it into a plan against indexes. My point wasn’t simply that a table is actually just a Clustered Index (or heap, which I consider just a special type of index), but that data access always happens against indexes – never tables – and we should be thinking about the indexes (specifically the non-clustered ones) when we write our queries. I described the scenario of looking up phone numbers, and how it never really occurs to us that there is a master list of phone numbers, because we think in terms of the useful non-clustered indexes that the phone companies provide us, but anyway – that’s not the point of this post. So a table is metadata. It stores information about the names of columns and their data types. Nullability, default values, constraints, triggers – these are all things that define the table, but the data isn’t stored in the table. The data that a table describes is stored in a heap or clustered index, but it goes further than this. All the useful data is going to live in non-clustered indexes. Remember this. It’s important. Stop thinking about tables, and start thinking about indexes. So let’s think about tables as indexes. This applies even in a world created by someone else, who doesn’t have the best indexes in mind for you. I’m sure you don’t need me to explain Covering Index bit – the fact that if you don’t have sufficient columns “included” in your index, your query plan will either have to do a Lookup, or else it’ll give up using your index and use one that does have everything it needs (even if that means scanning it). If you haven’t seen that before, drop me a line and I’ll run through it with you. Or go and read a post I did a long while ago about the maths involved in that decision. So – what I’m going to tell you is that a Lookup is a join. When I run SELECT CustomerID FROM Sales.SalesOrderHeader WHERE SalesPersonID = 285; against the AdventureWorks2012 get the following plan: I’m sure you can see the join. Don’t look in the query, it’s not there. But you should be able to see the join in the plan. It’s an Inner Join, implemented by a Nested Loop. It’s pulling data in from the Index Seek, and joining that to the results of a Key Lookup. It clearly is – the QO wouldn’t call it that if it wasn’t really one. It behaves exactly like any other Nested Loop (Inner Join) operator, pulling rows from one side and putting a request in from the other. You wouldn’t have a problem accepting it as a join if the query were slightly different, such as SELECT sod.OrderQty FROM Sales.SalesOrderHeader AS soh JOIN Sales.SalesOrderDetail as sod on sod.SalesOrderID = soh.SalesOrderID WHERE soh.SalesPersonID = 285; Amazingly similar, of course. This one is an explicit join, the first example was just as much a join, even thought you didn’t actually ask for one. You need to consider this when you’re thinking about your queries. But it gets more interesting. Consider this query: SELECT SalesOrderID FROM Sales.SalesOrderHeader WHERE SalesPersonID = 276 AND CustomerID = 29522; It doesn’t look like there’s a join here either, but look at the plan. That’s not some Lookup in action – that’s a proper Merge Join. The Query Optimizer has worked out that it can get the data it needs by looking in two separate indexes and then doing a Merge Join on the data that it gets. Both indexes used are ordered by the column that’s indexed (one on SalesPersonID, one on CustomerID), and then by the CIX key SalesOrderID. Just like when you seek in the phone book to Farley, the Farleys you have are ordered by FirstName, these seek operations return the data ordered by the next field. This order is SalesOrderID, even though you didn’t explicitly put that column in the index definition. The result is two datasets that are ordered by SalesOrderID, making them very mergeable. Another example is the simple query SELECT CustomerID FROM Sales.SalesOrderHeader WHERE SalesPersonID = 276; This one prefers a Hash Match to a standard lookup even! This isn’t just ordinary index intersection, this is something else again! Just like before, we could imagine it better with two whole tables, but we shouldn’t try to distinguish between joining two tables and joining two indexes. The Query Optimizer can see (using basic maths) that it’s worth doing these particular operations using these two less-than-ideal indexes (because of course, the best indexese would be on both columns – a composite such as (SalesPersonID, CustomerID – and it would have the SalesOrderID column as part of it as the CIX key still). You need to think like this too. Not in terms of excusing single-column indexes like the ones in AdventureWorks2012, but in terms of having a picture about how you’d like your queries to run. If you start to think about what data you need, where it’s coming from, and how it’s going to be used, then you will almost certainly write better queries. …and yes, this would include when you’re dealing with regular joins across multiples, not just against joins within single table queries.

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  • Stored Procedures with SSRS? Hmm… not so much

    - by Rob Farley
    Little Bobby Tables’ mother says you should always sanitise your data input. Except that I think she’s wrong. The SQL Injection aspect is for another post, where I’ll show you why I think SQL Injection is the same kind of attack as many other attacks, such as the old buffer overflow, but here I want to have a bit of a whinge about the way that some people sanitise data input, and even have a whinge about people who insist on using stored procedures for SSRS reports. Let me say that again, in case you missed it the first time: I want to have a whinge about people who insist on using stored procedures for SSRS reports. Let’s look at the data input sanitisation aspect – except that I’m going to call it ‘parameter validation’. I’m talking about code that looks like this: create procedure dbo.GetMonthSummaryPerSalesPerson(@eomdate datetime) as begin     /* First check that @eomdate is a valid date */     if isdate(@eomdate) != 1     begin         select 'Please enter a valid date' as ErrorMessage;         return;     end     /* Then check that time has passed since @eomdate */     if datediff(day,@eomdate,sysdatetime()) < 5     begin         select 'Sorry - EOM is not complete yet' as ErrorMessage;         return;     end         /* If those checks have succeeded, return the data */     select SalesPersonID, count(*) as NumSales, sum(TotalDue) as TotalSales     from Sales.SalesOrderHeader     where OrderDate >= dateadd(month,-1,@eomdate)         and OrderDate < @eomdate     group by SalesPersonID     order by SalesPersonID; end Notice that the code checks that a date has been entered. Seriously??!! This must only be to check for NULL values being passed in, because anything else would have to be a valid datetime to avoid an error. The other check is maybe fair enough, but I still don’t like it. The two problems I have with this stored procedure are the result sets and the small fact that the stored procedure even exists in the first place. But let’s consider the first one of these problems for starters. I’ll get to the second one in a moment. If you read Jes Borland (@grrl_geek)’s recent post about returning multiple result sets in Reporting Services, you’ll be aware that Reporting Services doesn’t support multiple results sets from a single query. And when it says ‘single query’, it includes ‘stored procedure call’. It’ll only handle the first result set that comes back. But that’s okay – we have RETURN statements, so our stored procedure will only ever return a single result set.  Sometimes that result set might contain a single field called ErrorMessage, but it’s still only one result set. Except that it’s not okay, because Reporting Services needs to know what fields to expect. Your report needs to hook into your fields, so SSRS needs to have a way to get that information. For stored procs, it uses an option called FMTONLY. When Reporting Services tries to figure out what fields are going to be returned by a query (or stored procedure call), it doesn’t want to have to run the whole thing. That could take ages. (Maybe it’s seen some of the stored procedures I’ve had to deal with over the years!) So it turns on FMTONLY before it makes the call (and turns it off again afterwards). FMTONLY is designed to be able to figure out the shape of the output, without actually running the contents. It’s very useful, you might think. set fmtonly on exec dbo.GetMonthSummaryPerSalesPerson '20030401'; set fmtonly off Without the FMTONLY lines, this stored procedure returns a result set that has three columns and fourteen rows. But with FMTONLY turned on, those rows don’t come back. But what I do get back hurts Reporting Services. It doesn’t run the stored procedure at all. It just looks for anything that could be returned and pushes out a result set in that shape. Despite the fact that I’ve made sure that the logic will only ever return a single result set, the FMTONLY option kills me by returning three of them. It would have been much better to push these checks down into the query itself. alter procedure dbo.GetMonthSummaryPerSalesPerson(@eomdate datetime) as begin     select SalesPersonID, count(*) as NumSales, sum(TotalDue) as TotalSales     from Sales.SalesOrderHeader     where     /* Make sure that @eomdate is valid */         isdate(@eomdate) = 1     /* And that it's sufficiently past */     and datediff(day,@eomdate,sysdatetime()) >= 5     /* And now use it in the filter as appropriate */     and OrderDate >= dateadd(month,-1,@eomdate)     and OrderDate < @eomdate     group by SalesPersonID     order by SalesPersonID; end Now if we run it with FMTONLY turned on, we get the single result set back. But let’s consider the execution plan when we pass in an invalid date. First let’s look at one that returns data. I’ve got a semi-useful index in place on OrderDate, which includes the SalesPersonID and TotalDue fields. It does the job, despite a hefty Sort operation. …compared to one that uses a future date: You might notice that the estimated costs are similar – the Index Seek is still 28%, the Sort is still 71%. But the size of that arrow coming out of the Index Seek is a whole bunch smaller. The coolest thing here is what’s going on with that Index Seek. Let’s look at some of the properties of it. Glance down it with me… Estimated CPU cost of 0.0005728, 387 estimated rows, estimated subtree cost of 0.0044385, ForceSeek false, Number of Executions 0. That’s right – it doesn’t run. So much for reading plans right-to-left... The key is the Filter on the left of it. It has a Startup Expression Predicate in it, which means that it doesn’t call anything further down the plan (to the right) if the predicate evaluates to false. Using this method, we can make sure that our stored procedure contains a single query, and therefore avoid any problems with multiple result sets. If we wanted, we could always use UNION ALL to make sure that we can return an appropriate error message. alter procedure dbo.GetMonthSummaryPerSalesPerson(@eomdate datetime) as begin     select SalesPersonID, count(*) as NumSales, sum(TotalDue) as TotalSales, /*Placeholder: */ '' as ErrorMessage     from Sales.SalesOrderHeader     where     /* Make sure that @eomdate is valid */         isdate(@eomdate) = 1     /* And that it's sufficiently past */     and datediff(day,@eomdate,sysdatetime()) >= 5     /* And now use it in the filter as appropriate */     and OrderDate >= dateadd(month,-1,@eomdate)     and OrderDate < @eomdate     group by SalesPersonID     /* Now include the error messages */     union all     select 0, 0, 0, 'Please enter a valid date' as ErrorMessage     where isdate(@eomdate) != 1     union all     select 0, 0, 0, 'Sorry - EOM is not complete yet' as ErrorMessage     where datediff(day,@eomdate,sysdatetime()) < 5     order by SalesPersonID; end But still I don’t like it, because it’s now a stored procedure with a single query. And I don’t like stored procedures that should be functions. That’s right – I think this should be a function, and SSRS should call the function. And I apologise to those of you who are now planning a bonfire for me. Guy Fawkes’ night has already passed this year, so I think you miss out. (And I’m not going to remind you about when the PASS Summit is in 2012.) create function dbo.GetMonthSummaryPerSalesPerson(@eomdate datetime) returns table as return (     select SalesPersonID, count(*) as NumSales, sum(TotalDue) as TotalSales, '' as ErrorMessage     from Sales.SalesOrderHeader     where     /* Make sure that @eomdate is valid */         isdate(@eomdate) = 1     /* And that it's sufficiently past */     and datediff(day,@eomdate,sysdatetime()) >= 5     /* And now use it in the filter as appropriate */     and OrderDate >= dateadd(month,-1,@eomdate)     and OrderDate < @eomdate     group by SalesPersonID     union all     select 0, 0, 0, 'Please enter a valid date' as ErrorMessage     where isdate(@eomdate) != 1     union all     select 0, 0, 0, 'Sorry - EOM is not complete yet' as ErrorMessage     where datediff(day,@eomdate,sysdatetime()) < 5 ); We’ve had to lose the ORDER BY – but that’s fine, as that’s a client thing anyway. We can have our reports leverage this stored query still, but we’re recognising that it’s a query, not a procedure. A procedure is designed to DO stuff, not just return data. We even get entries in sys.columns that confirm what the shape of the result set actually is, which makes sense, because a table-valued function is the right mechanism to return data. And we get so much more flexibility with this. If you haven’t seen the simplification stuff that I’ve preached on before, jump over to http://bit.ly/SimpleRob and watch the video of when I broke a microphone and nearly fell off the stage in Wales. You’ll see the impact of being able to have a simplifiable query. You can also read the procedural functions post I wrote recently, if you didn’t follow the link from a few paragraphs ago. So if we want the list of SalesPeople that made any kind of sales in a given month, we can do something like: select SalesPersonID from dbo.GetMonthSummaryPerSalesPerson(@eomonth) order by SalesPersonID; This doesn’t need to look up the TotalDue field, which makes a simpler plan. select * from dbo.GetMonthSummaryPerSalesPerson(@eomonth) where SalesPersonID is not null order by SalesPersonID; This one can avoid having to do the work on the rows that don’t have a SalesPersonID value, pushing the predicate into the Index Seek rather than filtering the results that come back to the report. If we had joins involved, we might see some of those being simplified out. We also get the ability to include query hints in individual reports. We shift from having a single-use stored procedure to having a reusable stored query – and isn’t that one of the main points of modularisation? Stored procedures in Reporting Services are just a bit limited for my liking. They’re useful in plenty of ways, but if you insist on using stored procedures all the time rather that queries that use functions – that’s rubbish. @rob_farley

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  • Streaming input to System.Speech.Recognition.SpeechRecognitionEngine

    - by spurserh
    I am trying to do "streaming" speech recognition in C# from a TCP socket. The problem I am having is that SpeechRecognitionEngine.SetInputToAudioStream() seems to require a Stream of a defined length which can seek. Right now the only way I can think to make this work is to repeatedly run the recognizer on a MemoryStream as more input comes in. Here's some code to illustrate: SpeechRecognitionEngine appRecognizer = new SpeechRecognitionEngine(); System.Speech.AudioFormat.SpeechAudioFormatInfo formatInfo = new System.Speech.AudioFormat.SpeechAudioFormatInfo(8000, System.Speech.AudioFormat.AudioBitsPerSample.Sixteen, System.Speech.AudioFormat.AudioChannel.Mono); NetworkStream stream = new NetworkStream(socket,true); appRecognizer.SetInputToAudioStream(stream, formatInfo); // At the line above a "NotSupportedException" complaining that "This stream does not support seek operations." Does anyone know how to get around this? It must support streaming input of some sort, since it works fine with the microphone using SetInputToDefaultAudioDevice(). Thanks, Sean

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  • Synchronization requirements for FileStream.(Begin/End)(Read/Write)

    - by Doug McClean
    Is the following pattern of multi-threaded calls acceptable to a .Net FileStream? Several threads calling a method like this: ulong offset = whatever; // different for each thread byte[] buffer = new byte[8192]; object state = someState; // unique for each call, hence also for each thread lock(theFile) { theFile.Seek(whatever, SeekOrigin.Begin); IAsyncResult result = theFile.BeginRead(buffer, 0, 8192, AcceptResults, state); } if(result.CompletedSynchronously) { // is it required for us to call AcceptResults ourselves in this case? // or did BeginRead already call it for us, on this thread or another? } Where AcceptResults is: void AcceptResults(IAsyncResult result) { lock(theFile) { int bytesRead = theFile.EndRead(result); // if we guarantee that the offset of the original call was at least 8192 bytes from // the end of the file, and thus all 8192 bytes exist, can the FileStream read still // actually read fewer bytes than that? // either: if(bytesRead != 8192) { Panic("Page read borked"); } // or: // issue a new call to begin read, moving the offsets into the FileStream and // the buffer, and decreasing the requested size of the read to whatever remains of the buffer } } I'm confused because the documentation seems unclear to me. For example, the FileStream class says: Any public static members of this type are thread safe. Any instance members are not guaranteed to be thread safe. But the documentation for BeginRead seems to contemplate having multiple read requests in flight: Multiple simultaneous asynchronous requests render the request completion order uncertain. Are multiple reads permitted to be in flight or not? Writes? Is this the appropriate way to secure the location of the Position of the stream between the call to Seek and the call to BeginRead? Or does that lock need to be held all the way to EndRead, hence only one read or write in flight at a time? I understand that the callback will occur on a different thread, and my handling of state, buffer handle that in a way that would permit multiple in flight reads. Further, does anyone know where in the documentation to find the answers to these questions? Or an article written by someone in the know? I've been searching and can't find anything. Relevant documentation: FileStream class Seek method BeginRead method EndRead IAsyncResult interface

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  • Get last n lines of a file with Python, similar to tail

    - by Armin Ronacher
    I'm writing a log file viewer for a web application and for that I want to paginate through the lines of the log file. The items in the file are line based with the newest item on the bottom. So I need a tail() method that can read n lines from the bottom and supports an offset. What I came up with looks like this: def tail(f, n, offset=0): """Reads a n lines from f with an offset of offset lines.""" avg_line_length = 74 to_read = n + offset while 1: try: f.seek(-(avg_line_length * to_read), 2) except IOError: # woops. apparently file is smaller than what we want # to step back, go to the beginning instead f.seek(0) pos = f.tell() lines = f.read().splitlines() if len(lines) >= to_read or pos == 0: return lines[-to_read:offset and -offset or None] avg_line_length *= 1.3 Is this a reasonable approach? What is the recommended way to tail log files with offsets?

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  • Python and Gstreamer

    - by Seif Sallam
    hi, I'm creating a streaming application, using GStreamer with TCP pipeline, and i implemented start, pause, and stop. but the problem is, that i can't seek, i tried to change the playback value from the server side, then i tried on the client side, and Finally tried to change the value on both at the same time, but in all cases it doesn't work. and I even tried to pause the playback then continue but nothing happens. I'm having this problem with the seek and the volume. Any help please, I searched everywhere but i couldn't find anything that worked. this is the code that i use for seeking self.pipeline.seek_simple(gst.FORMAT_TIME, gst.SEEK_FLAG_FLUSH, time)

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  • Recommendations for a C++ polymorphic, seekable, binary I/O interface

    - by Trevor Robinson
    I've been using std::istream and ostream as a polymorphic interface for random-access binary I/O in C++, but it seems suboptimal in numerous ways: 64-bit seeks are non-portable and error-prone due to streampos/streamoff limitations; currently using boost/iostreams/positioning.hpp as a workaround, but it requires vigilance Missing operations such as truncating or extending a file (ala POSIX ftruncate) Inconsistency between concrete implementations; e.g. stringstream has independent get/put positions whereas filestream does not Inconsistency between platform implementations; e.g. behavior of seeking pass the end of a file or usage of failbit/badbit on errors Don't need all the formatting facilities of stream or possibly even the buffering of streambuf streambuf error reporting (i.e. exceptions vs. returning an error indicator) is supposedly implementation-dependent in practice I like the simplified interface provided by the Boost.Iostreams Device concept, but it's provided as function templates rather than a polymorphic class. (There is a device class, but it's not polymorphic and is just an implementation helper class not necessarily used by the supplied device implementations.) I'm primarily using large disk files, but I really want polymorphism so I can easily substitute alternate implementations (e.g. use stringstream instead of fstream for unit tests) without all the complexity and compile-time coupling of deep template instantiation. Does anyone have any recommendations of a standard approach to this? It seems like a common situation, so I don't want to invent my own interfaces unnecessarily. As an example, something like java.nio.FileChannel seems ideal. My best solution so far is to put a thin polymorphic layer on top of Boost.Iostreams devices. For example: class my_istream { public: virtual std::streampos seek(stream_offset off, std::ios_base::seekdir way) = 0; virtual std::streamsize read(char* s, std::streamsize n) = 0; virtual void close() = 0; }; template <class T> class boost_istream : public my_istream { public: boost_istream(const T& device) : m_device(device) { } virtual std::streampos seek(stream_offset off, std::ios_base::seekdir way) { return boost::iostreams::seek(m_device, off, way); } virtual std::streamsize read(char* s, std::streamsize n) { return boost::iostreams::read(m_device, s, n); } virtual void close() { boost::iostreams::close(m_device); } private: T m_device; };

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  • c program for this quesion

    - by sashi
    suppose that a disk drive has 5000 cylinders, numbered 0 to 4999. the drive is currently serving a request at cylinder 143 and the previous request was at cylinder 125. the ueue of pending requests in the given order is 86,1470,913,17774,948,1509,1022,1750,130. write a 'c' program for finding the total distance in cylinders that the disk arm moves to satisfy all the pending reuests from the current heads position, using SSTF scheduling algorith. seek time is the time for the disk arm to move the head to the cylider containing the desired sector. sstf algorithm selects the minimum seek time from the current head position.

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  • Options for header in raw byte file.

    - by Tim
    I have a large raw data file (up to 1GB) which contains raw samples from a USB data logger. I need to store extra information relating to the file (sample rate, description, trigger point, last seek position etc) and was looking into adding this as a some sort of header. The header file should ideally be human readable and flexible so I've so far ruled out some sort of binary serialization into a header. I also want to avoid two separate files as they could end up separated when copied or backed up. I remembered somebody telling me that newer *.*x Microsoft Office documents are actually a number of files in a zip. Is there a simple way to achieve this? Could I still keep the quick seek times to the raw file?

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  • Querying Postgresql with a very large result set

    - by sanity
    In an application I need to query a Postgres DB where I expect tens or even hundreds of millions of rows in the result set. I might do this query once a day, or even more frequently. The query itself is relatively simple, although may involve a few JOINs. My question is: How smart is Postgres with respect to avoiding having to seek around the disk for each row of the result set? Given the time required for a hard disk seek, this could be extremely expensive. If this isn't an issue, how does Postgres avoid it? How does it know how to lay out data on the disk such that it can be streamed out in an efficient manner in response to this query?

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  • How to Research Keywords - 2 Sure Fire Ways to Get Buying Keywords

    When you seek information on "how to research keywords" you are told to search out long tail keywords with low competition and good search volume. What they don't tell is how to separate the info seekers from the buyers. Did you know that when a person sets out to search for something online they're either a) looking for information on a specific thing or b) looking to buy the specific thing!

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  • SQL SERVER Force Index Scan on Table Use No Index to Retrieve the Data Query Hint

    Recently I received the following two questions from readers and both the questions have very similar answers.Question 1: I have a unique requirement where I do not want to use any index of the table; how can I achieve this?Question 2: Currently my table uses clustered index and does seek operation; how can I convert [...]...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • 5 Helpful Tips When Hiring Freelance IT Help

    I recently finished creating my latest website, and since I am a designer, not a coder, I often find the need to seek the services of a freelance IT professional. There are several good sites out the... [Author: John Chilton - Computers and Internet - August 24, 2009]

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  • Listen to Local FM Radio in Windows 7 Media Center

    - by DigitalGeekery
    If you have a supported tuner card and connected FM antenna, you can listen to your favorite local over-the-air FM stations in Windows 7 Media Center. Before the FM radio option will be available in Windows Media Center, you’ll need to have a TV or Radio tuner card installed and configured. If you have a TV tuner card installed, you may already have a Radio tuner as well. Many TV tuner cards also have built in FM tuners. Open Windows Media Center, scroll the “Music” and over to “Radio.” Click on “FM Radio.”   The radio will turn on and you’ll see the current station number listed in the white box. Just below are standard “Seek” and “Tune” buttons, as well as “Preset” options. Tuning works just like a typical FM radio. Click on the (-) or (+) buttons to “Tune” or “Seek” up and down the dial. If you already know the frequency of the station, enter the numbers using the numeric keypad on the remote control or keyboard. To save the current station you’re listening to as a preset, click on the “Save as Preset” button. Type in a custom name for your preset station and click “Save.”   Once you set your presets, they will also be available on the main FM Radio screen. The transport controls at the bottom of the screen also allow you to control Volume, Pause, Play, Skip back, and Skip forward. Fast Forward and Rewind, however, are not supported.   This is a nice option if you’d like to listen to your local FM favorites on your computer, especially if those stations aren’t available online. If you don’t have an FM tuner and want to listen to thousands of online radio streams, check out our article on RadioTime in WMC. Similar Articles Productive Geek Tips Listen to Over 100,000 Radio Stations in Windows Media CenterListen To XM Radio with Windows Media Center in Windows 7Using Netflix Watchnow in Windows Vista Media Center (Gmedia)Schedule Updates for Windows Media CenterIntegrate Hulu Desktop and Windows Media Center in Windows 7 TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 PCmover Professional The Growth of Citibank Quickly Switch between Tabs in IE Windows Media Player 12: Tweak Video & Sound with Playback Enhancements Own a cell phone, or does a cell phone own you? Make your Joomla & Drupal Sites Mobile with OSMOBI Integrate Twitter and Delicious and Make Life Easier

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  • SQL SERVER – Quiz and Video – Introduction to Basics of a Query Hint

    - by pinaldave
    This blog post is inspired from SQL Architecture Basics Joes 2 Pros: Core Architecture concepts – SQL Exam Prep Series 70-433 – Volume 3. [Amazon] | [Flipkart] | [Kindle] | [IndiaPlaza] This is follow up blog post of my earlier blog post on the same subject - SQL SERVER – Introduction to Basics of a Query Hint – A Primer. In the article we discussed various basics terminology of the query hints. The article further covers following important concepts of query hints. Expecting Seek and getting a Scan Creating an index for improved optimization Implementing the query hint Above three are the most important concepts related to query hint and SQL Server.  There are many more things one has to learn but without beginners fundamentals one can’t learn the advanced  concepts. Let us have small quiz and check how many of you get the fundamentals right. Quiz 1) You have the following query: DECLARE @UlaChoice TinyInt SET @Type = 1 SELECT * FROM LegalActivity WHERE UlaChoice = @UlaChoice You have a nonclustered index named IX_Legal_Ula on the UlaChoice field. The Primary key is on the ID field and called PK_Legal_ID 99% of the time the value of the @UlaChoice is set to ‘YP101′. What query will achieve the best optimization for this query? SELECT * FROM LegalActivity WHERE UlaChoice = @UlaChoice WITH(INDEX(X_Legal_Ula)) SELECT * FROM LegalActivity WHERE UlaChoice = @UlaChoice WITH(INDEX(PK_Legal_ID)) SELECT * FROM LegalActivity WHERE UlaChoice = @UlaChoice OPTION (Optimize FOR(@UlaChoice = ‘YP101′)) 2) You have the following query: SELECT * FROM CurrentProducts WHERE ShortName = ‘Yoga Trip’ You have a nonclustered index on the ShortName field and the query runs an efficient index seek. You change your query to use a variable for ShortName and now you are using a slow index scan. What query hint can you use to get the same execution time as before? WITH LOCK FAST OPTIMIZE FOR MAXDOP READONLY Now make sure that you write down all the answers on the piece of paper. Watch following video and read earlier article over here. If you want to change the answer you still have chance. Solution 1) 3 2) 4 Now compare let us check the answers and compare your answers to following answers. I am very confident you will get them correct. Available at USA: Amazon India: Flipkart | IndiaPlaza Volume: 1, 2, 3, 4, 5 Please leave your feedback in the comment area for the quiz and video. Did you know all the answers of the quiz? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Joes 2 Pros, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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