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• SQL SERVER – OLEDB – Link Server – Wait Type – Day 23 of 28

  - by pinaldave

  When I decided to start writing about this wait type, the very first question that came to my mind was, “What does ‘OLEDB’ stand for?” A quick search on Wikipedia tells me that OLEDB means Object Linking and Embedding Database. (How many of you knew this?) Anyway, I found it very interesting that this wait type was in one of the top 10 wait types in many of the systems I have come across in my performance tuning experience. Books On-Line: ????OLEDB occurs when SQL Server calls the SQL Server Native Client OLE DB Provider. This wait type is not used for synchronization. Instead, it indicates the duration of calls to the OLE DB provider. OLEDB Explanation: This wait type primarily happens when Link Server or Remove Query has been executed. The most common case wherein this wait type is visible is during the execution of Linked Server. When SQL Server is retrieving data from the remote server, it uses OLEDB API to retrieve the data. It is possible that the remote system is not quick enough or the connection between them is not fast enough, leading SQL Server to wait for the result’s return from the remote (or external) server. This is the time OLEDB wait type occurs. Reducing OLEDB wait: Check the Link Server configuration. Checking Disk-Related Perfmon Counters Average Disk sec/Read (Consistent higher value than 4-8 millisecond is not good) Average Disk sec/Write (Consistent higher value than 4-8 millisecond is not good) Average Disk Read/Write Queue Length (Consistent higher value than benchmark is not good) At this point in time, I am not able to think of any more ways on reducing this wait type. Do you have any opinion about this subject? Please share it here and I will share your comment with the rest of the Community, and of course, with due credit unto you. Please read all the post in the Wait Types and Queue series. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussion of Wait Stats in this blog is generic and varies from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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• The internal storage of a DATETIME value

  - by Peter Larsson

  SELECT  [Now],         BinaryFormat,         SUBSTRING(BinaryFormat, 1, 4) AS DayPart,         SUBSTRING(BinaryFormat, 5, 4) AS TimePart,         CAST(SUBSTRING(BinaryFormat, 1, 4) AS INT) AS [Days],         DATEADD(DAY, CAST(SUBSTRING(BinaryFormat, 1, 4) AS INT), 0) AS [Today],         CAST(SUBSTRING(BinaryFormat, 5, 4) AS INT) AS [Ticks],         DATEADD(MILLISECOND, 1000.E / 300.E * CAST(SUBSTRING(BinaryFormat, 5, 4) AS INT), 0) AS Peso FROM    (             SELECT  GETDATE() AS [Now],                     CAST(GETDATE() AS BINARY(8)) AS BinaryFormat         ) AS d

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• How to create a GLib.TimeVal from timestamp?

  - by fluteflute

  I have a value such as 'timestamp' below, where the last three digits correspond to milliseconds. timestamp = 1340830988768 I currently have code that looks like the following: import indicate indicator = indicate.Indicator() indicator.set_property_time("time", int(timestamp[:-3])) I want to amend it to use: from gi.repository import Indicate indicator = Indicate.Indicator() However, the new version of set_property_time requires the second parameter to be a GLib.TimeVal. How do I create a GLib.TimeVal from my timestamp? Millisecond precision is not important for this application.

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• Is it OK to repeat code for unit tests?

  - by Pete

  I wrote some sorting algorithms for a class assignment and I also wrote a few tests to make sure the algorithms were implemented correctly. My tests are only like 10 lines long and there are 3 of them but only 1 line changes between the 3 so there is a lot of repeated code. Is it better to refactor this code into another method that is then called from each test? Wouldn't I then need to write another test to test the refactoring? Some of the variables can even be moved up to the class level. Should testing classes and methods follow the same rules as regular classes/methods? Here's an example: [TestMethod] public void MergeSortAssertArrayIsSorted() { int[] a = new int[1000]; Random rand = new Random(DateTime.Now.Millisecond); for(int i = 0; i < a.Length; i++) { a[i] = rand.Next(Int16.MaxValue); } int[] b = new int[1000]; a.CopyTo(b, 0); List<int> temp = b.ToList(); temp.Sort(); b = temp.ToArray(); MergeSort merge = new MergeSort(); merge.mergeSort(a, 0, a.Length - 1); CollectionAssert.AreEqual(a, b); } [TestMethod] public void InsertionSortAssertArrayIsSorted() { int[] a = new int[1000]; Random rand = new Random(DateTime.Now.Millisecond); for (int i = 0; i < a.Length; i++) { a[i] = rand.Next(Int16.MaxValue); } int[] b = new int[1000]; a.CopyTo(b, 0); List<int> temp = b.ToList(); temp.Sort(); b = temp.ToArray(); InsertionSort merge = new InsertionSort(); merge.insertionSort(a); CollectionAssert.AreEqual(a, b); }

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• Monitor Review: ViewSonic VX2739wm

  If the idea of getting a spacious 27-inch HD monitor for $349 doesn't get your attention, how about one with a 1-millisecond response time? We check out ViewSonic's Blu-ray- and game-worthy widescreen.

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• Monitor Review: ViewSonic VX2739wm

  If the idea of getting a spacious 27-inch HD monitor for $349 doesn't get your attention, how about one with a 1-millisecond response time? We check out ViewSonic's Blu-ray- and game-worthy widescreen.

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• SQL SERVER – ASYNC_IO_COMPLETION – Wait Type – Day 11 of 28

  - by pinaldave

  For any good system three things are vital: CPU, Memory and IO (disk). Among these three, IO is the most crucial factor of SQL Server. Looking at real-world cases, I do not see IT people upgrading CPU and Memory frequently. However, the disk is often upgraded for either improving the space, speed or throughput. Today we will look at another IO-related wait type. From Book On-Line: Occurs when a task is waiting for I/Os to finish. ASYNC_IO_COMPLETION Explanation: Any tasks are waiting for I/O to finish. If by any means your application that’s connected to SQL Server is processing the data very slowly, this type of wait can occur. Several long-running database operations like BACKUP, CREATE DATABASE, ALTER DATABASE or other operations can also create this wait type. Reducing ASYNC_IO_COMPLETION wait: When it is an issue related to IO, one should check for the following things associated to IO subsystem: Look at the programming and see if there is any application code which processes the data slowly (like inefficient loop, etc.). Note that it should be re-written to avoid this  wait type. Proper placing of the files is very important. We should check the file system for proper placement of the files – LDF and MDF on separate drive, TempDB on another separate drive, hot spot tables on separate filegroup (and on separate disk), etc. Check the File Statistics and see if there is a higher IO Read and IO Write Stall SQL SERVER – Get File Statistics Using fn_virtualfilestats. Check event log and error log for any errors or warnings related to IO. If you are using SAN (Storage Area Network), check the throughput of the SAN system as well as configuration of the HBA Queue Depth. In one of my recent projects, the SAN was performing really badly and so the SAN administrator did not accept it. After some investigations, he agreed to change the HBA Queue Depth on the development setup (test environment). As soon as we changed the HBA Queue Depth to quite a higher value, there was a sudden big improvement in the performance. It is very likely to happen that there are no proper indexes on the system and yet there are lots of table scans and heap scans. Creating proper index can reduce the IO bandwidth considerably. If SQL Server can use appropriate cover index instead of clustered index, it can effectively reduce lots of CPU, Memory and IO (considering cover index has lesser columns than cluster table and all other; it depends upon the situation). You can refer to the following two articles I wrote that talk about how to optimize indexes: Create Missing Indexes Drop Unused Indexes Checking Memory Related Perfmon Counters SQLServer: Memory Manager\Memory Grants Pending (Consistent higher value than 0-2) SQLServer: Memory Manager\Memory Grants Outstanding (Consistent higher value, Benchmark) SQLServer: Buffer Manager\Buffer Hit Cache Ratio (Higher is better, greater than 90% for usually smooth running system) SQLServer: Buffer Manager\Page Life Expectancy (Consistent lower value than 300 seconds) Memory: Available Mbytes (Information only) Memory: Page Faults/sec (Benchmark only) Memory: Pages/sec (Benchmark only) Checking Disk Related Perfmon Counters Average Disk sec/Read (Consistent higher value than 4-8 millisecond is not good) Average Disk sec/Write (Consistent higher value than 4-8 millisecond is not good) Average Disk Read/Write Queue Length (Consistent higher value than benchmark is not good) Read all the post in the Wait Types and Queue series. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussions of Wait Stats in this blog are generic and vary from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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• SQL SERVER – IO_COMPLETION – Wait Type – Day 10 of 28

  - by pinaldave

  For any good system three things are vital: CPU, Memory and IO (disk). Among these three, IO is the most crucial factor of SQL Server. Looking at real-world cases, I do not see IT people upgrading CPU and Memory frequently. However, the disk is often upgraded for either improving the space, speed or throughput. Today we will look at an IO-related wait types. From Book On-Line: Occurs while waiting for I/O operations to complete. This wait type generally represents non-data page I/Os. Data page I/O completion waits appear as PAGEIOLATCH_* waits. IO_COMPLETION Explanation: Any tasks are waiting for I/O to finish. This is a good indication that IO needs to be looked over here. Reducing IO_COMPLETION wait: When it is an issue concerning the IO, one should look at the following things related to IO subsystem: Proper placing of the files is very important. We should check the file system for proper placement of files – LDF and MDF on a separate drive, TempDB on another separate drive, hot spot tables on separate filegroup (and on separate disk),etc. Check the File Statistics and see if there is higher IO Read and IO Write Stall SQL SERVER – Get File Statistics Using fn_virtualfilestats. Check event log and error log for any errors or warnings related to IO. If you are using SAN (Storage Area Network), check the throughput of the SAN system as well as the configuration of the HBA Queue Depth. In one of my recent projects, the SAN was performing really badly so the SAN administrator did not accept it. After some investigations, he agreed to change the HBA Queue Depth on development (test environment) set up and as soon as we changed the HBA Queue Depth to quite a higher value, there was a sudden big improvement in the performance. It is very possible that there are no proper indexes in the system and there are lots of table scans and heap scans. Creating proper index can reduce the IO bandwidth considerably. If SQL Server can use appropriate cover index instead of clustered index, it can effectively reduce lots of CPU, Memory and IO (considering cover index has lesser columns than cluster table and all other; it depends upon the situation). You can refer to the two articles that I wrote; they are about how to optimize indexes: Create Missing Indexes Drop Unused Indexes Checking Memory Related Perfmon Counters SQLServer: Memory Manager\Memory Grants Pending (Consistent higher value than 0-2) SQLServer: Memory Manager\Memory Grants Outstanding (Consistent higher value, Benchmark) SQLServer: Buffer Manager\Buffer Hit Cache Ratio (Higher is better, greater than 90% for usually smooth running system) SQLServer: Buffer Manager\Page Life Expectancy (Consistent lower value than 300 seconds) Memory: Available Mbytes (Information only) Memory: Page Faults/sec (Benchmark only) Memory: Pages/sec (Benchmark only) Checking Disk Related Perfmon Counters Average Disk sec/Read (Consistent higher value than 4-8 millisecond is not good) Average Disk sec/Write (Consistent higher value than 4-8 millisecond is not good) Average Disk Read/Write Queue Length (Consistent higher value than benchmark is not good) Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussions of Wait Stats in this blog are generic and vary from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Types, SQL White Papers, T SQL, Technology

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• Strange behaviour with GregorianCalendar

  - by Spark

  I just encountered a strange behaviour with the GregorianCalendar class, and I was wondering if I really was doing something bad. This only appends when the initialization date's month has an actualMaximum bigger than the month I'm going to set the calendar to. Here is the example code : // today is 2010/05/31 GregorianCalendar cal = new GregorianCalendar(); cal.set(Calendar.YEAR, 2010); cal.set(Calendar.MONTH, 1); // FEBRUARY cal.set(Calendar.DAY_OF_MONTH, cal.getActualMaximum(Calendar.DAY_OF_MONTH)); cal.set(Calendar.HOUR_OF_DAY, cal.getActualMaximum(Calendar.HOUR_OF_DAY)); cal.set(Calendar.MINUTE, cal.getActualMaximum(Calendar.MINUTE)); cal.set(Calendar.SECOND, cal.getActualMaximum(Calendar.SECOND)); cal.set(Calendar.MILLISECOND, cal.getActualMaximum(Calendar.MILLISECOND)); return cal.getTime(); // => 2010/03/03, wtf I know the problem is caused by the fact that the calendar initialization date is a 31 day month ( may ), which mess with the month set to february (28 days). The fix is easy ( just set day_of_month to 1 before setting year and month ), but I was wondering is this really was the wanted behaviour. Any thoughts ?

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• java gregorian calendar timer

  - by Ieyasu Sawada

  I have this java program which calculates the time that the person took to respond to the confirm dialog box. But it seems that both time1 and time 2 gets the same value. What have I done wrong here: import javax.swing.JOptionPane; import java.util.*; public class DialogTimer{ public static void main(String args[]){ int time1, time2, milli1, milli2, sec1, sec2, timeDifference; final int MILLISECSINSECOND =1000; JOptionPane.showConfirmDialog(null, "Is stealing ever justified? "); GregorianCalendar before=new GregorianCalendar(); GregorianCalendar after= new GregorianCalendar(); milli1=before.get(GregorianCalendar.MILLISECOND); milli2=after.get(GregorianCalendar.MILLISECOND); sec1=before.get(GregorianCalendar.SECOND); sec2=after.get(GregorianCalendar.SECOND); time1=MILLISECSINSECOND * sec1 + milli1; time2=MILLISECSINSECOND * sec2 + milli2; //timeDifference=time1 - time2; System.out.println(time1); System.out.println(time2); //JOptionPane.showMessageDialog(null, "It took " + (time1 - time2) + " milliseconds for you to answer"); } }

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• shell script filter du and find by a string inside a file in a subfolder

  - by Jason

  I have the following command that I run on cygwin: find /cygdrive/d/tmp/* -maxdepth 0 -mtime -150 -type d | xargs du --max-depth=0 > foldersizesreport.csv I intended to do the following with this command: for each folder under /d/tmp/ that was modified in last 150 days, check its total size including files within it and report it to file foldersizesreport.csv however that is now not good enough for me, as it turns out inside each /d/tmp/subfolder1/somefile.properties /d/tmp/subfolder2/somefile.properties /d/tmp/subfolder3/somefile.properties /d/tmp/subfolder4/somefile.properties so as you see inside each subfolderX there is a file named somefile.properties inside it there is a property SOMEPROPKEY=3808612800100 (among other properties) this is the time in millisecond, i need to change the command so that instead of -mtime -150 it will include in the whole calculation only subfolderX that has a file inside them somefile.properties where the SOMEPROPKEY=3808612800100 is the time in millisecond in future, if the value SOMEPROPKEY=23948948 is in past then dont at all include the folder in the foldersizesreport.csv because its not relevant to me. so the result report should be looking like: /d/tmp/,subfolder1,<itssizein KB> /d/tmp/,subfolder2,<itssizein KB> and if subfolder3 had a SOMEPROPKEY=34243234 (time in ms in past) then it would not be in that csv file. so basically I'm looking for: find /cygdrive/d/tmp/* -maxdepth 0 -mtime -150 -type d | <only subfolders that have in them property in file SOMEPROPKEY=28374874827 - time in ms in future and not in past | xargs du --max-depth=0 > foldersizesreport.csv

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• C# Timer -- measuring time slower

  - by Fassenkugel

  I'm writing a code where: I.) The user adds "events" during run-time. (To a flowlayoutpanel) These events are turning some LEDs on/off, after "x" time has elapsed and the LED-turning functions are written in a Led-function.cs class. i.e: 1) Turn left led on After 3500ms 2) Turn right led on After 4000ms II.) When the user hits start a timer starts. // Create timer. System.Timers.Timer _timer; _timer = new System.Timers.Timer(); _timer.Interval = (1); _timer.Elapsed += (sender, e) => { HandleTimerElapsed(LedObject, device, _timer); }; _timer.Start(); III.) The timer's tick event is raised every millisecond and checks if the user definied time has ellapsed. Im measuring the elapsed time with adding +1 to an integer at every tick event. (NumberOfTicks++;) //Timer Handle private void HandleTimerElapsed(Led_Functions LedObject, string device, System.Timers.Timer _timer) { NumberOfTicks++; if (NumberOfTicks >= Start_time[0]) { LedObject.LeftLED_ONnobutton(device); } } IV.) What I noticed was that when the tick was set to 1. (So the tick event is raised every millisecond) Even if I set 3000ms to the evet the LED actually flashed around 6 seconds. When the tick was set to 100. (So every 0,1s) then the flash was more accurate (3,5sec or so). Any Ideas why im having this delay in time? Or do you have any ideas how could I implement it better? Thank you!

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• How can ASP.NET's "Request Wait Time" be 0 when "Requests Queued" is consistently in the hundreds?

  - by ondrej

  I'm curious why Performance Monitor claims I always have a few hundred ASP.NET 3.5 requests "queued". The "Requests Queued" "ASP.NET v2.0.50727" performance counter is hovering in the few-hundred range despite the fact "Request Wait Time" is consistently 0. If each and every request never waits even a fraction of a millisecond, how could it be in the queue? The "ASP.NET Apps v2.0.50727" counters for "Requests In Application Queue" and "Request Wait Time" are always 0.

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• SQL SERVER – PAGEIOLATCH_DT, PAGEIOLATCH_EX, PAGEIOLATCH_KP, PAGEIOLATCH_SH, PAGEIOLATCH_UP – Wait Type – Day 9 of 28

  - by pinaldave

  It is very easy to say that you replace your hardware as that is not up to the mark. In reality, it is very difficult to implement. It is really hard to convince an infrastructure team to change any hardware because they are not performing at their best. I had a nightmare related to this issue in a deal with an infrastructure team as I suggested that they replace their faulty hardware. This is because they were initially not accepting the fact that it is the fault of their hardware. But it is really easy to say “Trust me, I am correct”, while it is equally important that you put some logical reasoning along with this statement. PAGEIOLATCH_XX is such a kind of those wait stats that we would directly like to blame on the underlying subsystem. Of course, most of the time, it is correct – the underlying subsystem is usually the problem. From Book On-Line: PAGEIOLATCH_DT Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Destroy mode. Long waits may indicate problems with the disk subsystem. PAGEIOLATCH_EX Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Exclusive mode. Long waits may indicate problems with the disk subsystem. PAGEIOLATCH_KP Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Keep mode. Long waits may indicate problems with the disk subsystem. PAGEIOLATCH_SH Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Shared mode. Long waits may indicate problems with the disk subsystem. PAGEIOLATCH_UP Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Update mode. Long waits may indicate problems with the disk subsystem. PAGEIOLATCH_XX Explanation: Simply put, this particular wait type occurs when any of the tasks is waiting for data from the disk to move to the buffer cache. ReducingPAGEIOLATCH_XX wait: Just like any other wait type, this is again a very challenging and interesting subject to resolve. Here are a few things you can experiment on: Improve your IO subsystem speed (read the first paragraph of this article, if you have not read it, I repeat that it is easy to say a step like this than to actually implement or do it). This type of wait stats can also happen due to memory pressure or any other memory issues. Putting aside the issue of a faulty IO subsystem, this wait type warrants proper analysis of the memory counters. If due to any reasons, the memory is not optimal and unable to receive the IO data. This situation can create this kind of wait type. Proper placing of files is very important. We should check file system for the proper placement of files – LDF and MDF on separate drive, TempDB on separate drive, hot spot tables on separate filegroup (and on separate disk), etc. Check the File Statistics and see if there is higher IO Read and IO Write Stall SQL SERVER – Get File Statistics Using fn_virtualfilestats. It is very possible that there are no proper indexes on the system and there are lots of table scans and heap scans. Creating proper index can reduce the IO bandwidth considerably. If SQL Server can use appropriate cover index instead of clustered index, it can significantly reduce lots of CPU, Memory and IO (considering cover index has much lesser columns than cluster table and all other it depends conditions). You can refer to the two articles’ links below previously written by me that talk about how to optimize indexes. Create Missing Indexes Drop Unused Indexes Updating statistics can help the Query Optimizer to render optimal plan, which can only be either directly or indirectly. I have seen that updating statistics with full scan (again, if your database is huge and you cannot do this – never mind!) can provide optimal information to SQL Server optimizer leading to efficient plan. Checking Memory Related Perfmon Counters SQLServer: Memory Manager\Memory Grants Pending (Consistent higher value than 0-2) SQLServer: Memory Manager\Memory Grants Outstanding (Consistent higher value, Benchmark) SQLServer: Buffer Manager\Buffer Hit Cache Ratio (Higher is better, greater than 90% for usually smooth running system) SQLServer: Buffer Manager\Page Life Expectancy (Consistent lower value than 300 seconds) Memory: Available Mbytes (Information only) Memory: Page Faults/sec (Benchmark only) Memory: Pages/sec (Benchmark only) Checking Disk Related Perfmon Counters Average Disk sec/Read (Consistent higher value than 4-8 millisecond is not good) Average Disk sec/Write (Consistent higher value than 4-8 millisecond is not good) Average Disk Read/Write Queue Length (Consistent higher value than benchmark is not good) Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All of the discussions of Wait Stats in this blog is generic and varies from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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• SQL SERVER – LCK_M_XXX – Wait Type – Day 15 of 28

  - by pinaldave

  Locking is a mechanism used by the SQL Server Database Engine to synchronize access by multiple users to the same piece of data, at the same time. In simpler words, it maintains the integrity of data by protecting (or preventing) access to the database object. From Book On-Line: LCK_M_BU Occurs when a task is waiting to acquire a Bulk Update (BU) lock. LCK_M_IS Occurs when a task is waiting to acquire an Intent Shared (IS) lock. LCK_M_IU Occurs when a task is waiting to acquire an Intent Update (IU) lock. LCK_M_IX Occurs when a task is waiting to acquire an Intent Exclusive (IX) lock. LCK_M_S Occurs when a task is waiting to acquire a Shared lock. LCK_M_SCH_M Occurs when a task is waiting to acquire a Schema Modify lock. LCK_M_SCH_S Occurs when a task is waiting to acquire a Schema Share lock. LCK_M_SIU Occurs when a task is waiting to acquire a Shared With Intent Update lock. LCK_M_SIX Occurs when a task is waiting to acquire a Shared With Intent Exclusive lock. LCK_M_U Occurs when a task is waiting to acquire an Update lock. LCK_M_UIX Occurs when a task is waiting to acquire an Update With Intent Exclusive lock. LCK_M_X Occurs when a task is waiting to acquire an Exclusive lock. LCK_M_XXX Explanation: I think the explanation of this wait type is the simplest. When any task is waiting to acquire lock on any resource, this particular wait type occurs. The common reason for the task to be waiting to put lock on the resource is that the resource is already locked and some other operations may be going on within it. This wait also indicates that resources are not available or are occupied at the moment due to some reasons. There is a good chance that the waiting queries start to time out if this wait type is very high. Client application may degrade the performance as well. You can use various methods to find blocking queries: EXEC sp_who2 SQL SERVER – Quickest Way to Identify Blocking Query and Resolution – Dirty Solution DMV – sys.dm_tran_locks DMV – sys.dm_os_waiting_tasks Reducing LCK_M_XXX wait: Check the Explicit Transactions. If transactions are very long, this wait type can start building up because of other waiting transactions. Keep the transactions small. Serialization Isolation can build up this wait type. If that is an acceptable isolation for your business, this wait type may be natural. The default isolation of SQL Server is ‘Read Committed’. One of my clients has changed their isolation to “Read Uncommitted”. I strongly discourage the use of this because this will probably lead to having lots of dirty data in the database. Identify blocking queries mentioned using various methods described above, and then optimize them. Partition can be one of the options to consider because this will allow transactions to execute concurrently on different partitions. If there are runaway queries, use timeout. (Please discuss this solution with your database architect first as timeout can work against you). Check if there is no memory and IO-related issue using the following counters: Checking Memory Related Perfmon Counters SQLServer: Memory Manager\Memory Grants Pending (Consistent higher value than 0-2) SQLServer: Memory Manager\Memory Grants Outstanding (Consistent higher value, Benchmark) SQLServer: Buffer Manager\Buffer Hit Cache Ratio (Higher is better, greater than 90% for usually smooth running system) SQLServer: Buffer Manager\Page Life Expectancy (Consistent lower value than 300 seconds) Memory: Available Mbytes (Information only) Memory: Page Faults/sec (Benchmark only) Memory: Pages/sec (Benchmark only) Checking Disk Related Perfmon Counters Average Disk sec/Read (Consistent higher value than 4-8 millisecond is not good) Average Disk sec/Write (Consistent higher value than 4-8 millisecond is not good) Average Disk Read/Write Queue Length (Consistent higher value than benchmark is not good) Read all the post in the Wait Types and Queue series. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussion of Wait Stats in this blog is generic and varies from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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• Podcast: Dell Perot Systems Relies on Oracle In-Memory Database Cache

  - by john.brust

  Recently we spoke with Bill Binko, Technology Consultant at Dell Perot Systems, about a high volume web-based content delivery system they implemented for a client with Oracle In-Memory Database Cache. Their client needed to respond to ~1 billion hits (web requests) per day, but hadn't been able to support this load. Oracle In-Memory Database Cache allowed for multiple & complicated queries to take place without ever hitting the disk...providing sub-millisecond response time and ability to manage much higher high volumes of data. Old System: Old SQL Server Database, over 300 servers, difficult to maintain. New System: One Oracle Database 11g instance, multiple Oracle RAC nodes, backed up by Oracle Data Guard, and Oracle In-Memory Database Cache to cut query response times by 10x. Listen to the podcast.

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• Acceptable GC frequency for a SlimDX/Windows/.NET game?

  - by Rei Miyasaka

  I understand that the Windows GC is much better than the Xbox/WP7 GC, being that it's generational and multithreaded -- so I don't need to worry quite as much about avoiding memory allocation. SlimDX even has some unavoidable functions that generate some amount of garbage (specifically, MapSubresource creates DataBoxes), yet people don't seem to be too upset about it. I'd like to use some functional paradigms to write my code too, which also means creating objects like closures and monads. I know premature optimization isn't a good thing, but are there rules of thumb or metrics that I can follow to know whether I need to cut down on allocations? Is, say, one gen 0 GC per frame too much? One thing that has me stumped is object promotions. Gen 0 GCs will supposedly finish within a millisecond or two, but if I'm understanding correctly, it's the gen 1 and 2 promotions that start to hurt. I'm not too sure how I can predict/prevent these.

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• 7-Eleven Mobile App Powered by Oracle SOA Suite

  - by Bruce Tierney

  When you slurp that Slurpee, do you ever think about the sub 100 millisecond processing of 20 million 7-Eleven digital transactions ever day supported by Oracle SOA Suite?  Maybe next time.  Check out this impressive video of Ronald Clanton, 7-Eleven's Digital Guest Experience Program Manager, describing how 7-Eleven provides a consistent view across all the end points of over 10,000 stores and their digital entities by using Oracle SOA Suite on Oracle Exalogic.  Managed by Oracle Enterprise Manager, they were able to provision their "Rapid-Fire" Middleware as a Service (MWaaS) in only "10 minutes" and deliver on time and complete testing ahead of schedule. So what are you waiting for?  Download your Slurpee App to get your free Pillsbury Cinnamon pastry and enjoy your contribution to the 20 million messages/day.   When your done, take picture of your tongue...red or blue?  Watch the video here:

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• What is an acceptable GC frequency for a SlimDX/Windows/.NET game?

  - by Rei Miyasaka

  I understand that the Windows GC is much better than the Xbox/WP7 GC, being that it's generational and multithreaded -- so I don't need to worry quite as much about avoiding memory allocation. SlimDX even has some unavoidable functions that generate some amount of garbage (specifically, MapSubresource creates DataBoxes), yet people don't seem to be too upset about it. I'd like to use some functional paradigms to write my code too, which also means creating objects like closures and monads. I know premature optimization isn't a good thing, but are there rules of thumb or metrics that I can follow to know whether I need to cut down on allocations? Is, say, one gen 0 GC per frame too much? One thing that has me stumped is object promotions. Gen 0 GCs will supposedly finish within a millisecond or two, but if I'm understanding correctly, it's the gen 1 and 2 promotions that start to hurt. I'm not too sure how I can predict/prevent these.

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• Google I/O 2012 - How we Make JavaScript Widgets Scream

  Google I/O 2012 - How we Make JavaScript Widgets Scream Malte Ubl, John Hjelmstad When loading websites every millisecond counts. Social widgets should enhance a website experience and they should definitely not slow it down. We'll walk through the unique challenges of loading social widgets such as the +1 button and how we made sure that they load as fast as possible -- yes, there will be war stories! While we'll focus on widget performance, many of the techniques we used have wider applicability and we'll show how they can make your website faster, too. For all I/O 2012 sessions, go to developers.google.com From: GoogleDevelopers Views: 734 3 ratings Time: 51:44 More in Science & Technology

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• how to display date in HH:mm:ss format in jasper report?

  - by Aru

  Hi, I am using following code to generate chart in jasper. I am printing date on X-axis. But it is displaying in millisecond. I want to display it in hh:mm:ss format. How to achieve it?

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• Jquery Count up Animation?

  - by Wes

  I have a a counter that needs to count up from $0 to $10,000 in x seconds (most likely 3 seconds). Just straight text, kind of like a millisecond countdown timer, but upwards and with a dollar sign. I'd rather not use a bulky plugin as this just needs to loop through 1-10,00 in x seconds and update every 100ms or so. I'm stuck at creating the loop that will update, where should I start?

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• Function that creates a timestamp in c#

  - by Konstantinos

  Hi there, I was wondering, is there a way to create a timestamp in c# from a datetime? I need a millisecond precision value that also works in Compact Framework(saying that since DateTime.ToBinary() does not exist in CF). My problem is that i want to store this value in a database agnostic way so i can sortby it later and find out which value is greater from another etc.

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• DateTime Comparison Precision

  - by mnh

  I'm doing DateTime comparison but I don't want to do comparison at second, millisecond and ticks level. What's the most elegant way? If I simply compare the DateTime, then they are seldom equal due to ticks differences.

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• Convert date, datetime to timestamp

  - by Beau Martínez

  How can I produce a timestamp to millisecond accuracy from a date or datetime in Python? There are an overwhelming number of methods and ways of doing this, and I'm wondering which is the most Pythonic way.

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