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  • commons-exec: hanging when I call executor.execute(commandLine);

    - by Stefan Kendall
    I have no idea why this is hanging. I'm trying to capture output from a process run through commons-exec, and I continue to hang. I've provided an example program to demonstrate this behavior below. import java.io.DataInputStream; import java.io.IOException; import java.io.PipedInputStream; import java.io.PipedOutputStream; import org.apache.commons.exec.CommandLine; import org.apache.commons.exec.DefaultExecutor; import org.apache.commons.exec.ExecuteException; import org.apache.commons.exec.PumpStreamHandler; public class test { public static void main(String[] args) { String command = "java"; PipedOutputStream output = new PipedOutputStream(); PumpStreamHandler psh = new PumpStreamHandler(output); CommandLine cl = CommandLine.parse(command); DefaultExecutor exec = new DefaultExecutor(); DataInputStream is = null; try { is = new DataInputStream(new PipedInputStream(output)); exec.setStreamHandler(psh); exec.execute(cl); } catch (ExecuteException ex) { } catch (IOException ex) { } System.out.println("huh?"); } }

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  • “Query cost (relative to the batch)” <> Query cost relative to batch

    - by Dave Ballantyne
    OK, so that is quite a contradictory title, but unfortunately it is true that a common misconception is that the query with the highest percentage relative to batch is the worst performing.  Simply put, it is a lie, or more accurately we dont understand what these figures mean. Consider the two below simple queries: SELECT * FROM Person.BusinessEntity JOIN Person.BusinessEntityAddress ON Person.BusinessEntity.BusinessEntityID = Person.BusinessEntityAddress.BusinessEntityID go SELECT * FROM Sales.SalesOrderDetail JOIN Sales.SalesOrderHeader ON Sales.SalesOrderDetail.SalesOrderID = Sales.SalesOrderHeader.SalesOrderID After executing these and looking at the plans, I see this : So, a 13% / 87% split ,  but 13% / 87% of WHAT ? CPU ? Duration ? Reads ? Writes ? or some magical weighted algorithm ?  In a Profiler trace of the two we can find the metrics we are interested in. CPU and duration are well out but what about reads (210 and 1935)? To save you doing the maths, though you are more than welcome to, that’s a 90.2% / 9.8% split.  Close, but no cigar. Lets try a different tact.  Looking at the execution plan the “Estimated Subtree cost” of query 1 is 0.29449 and query 2 its 1.96596.  Again to save you the maths that works out to 13.03% and 86.97%, round those and thats the figures we are after.  But, what is the worrying word there ? “Estimated”.  So these are not “actual”  execution costs,  but what’s the problem in comparing the estimated costs to derive a meaning of “Most Costly”.  Well, in the case of simple queries such as the above , probably not a lot.  In more complicated queries , a fair bit. By modifying the second query to also show the total number of lines on each order SELECT *,COUNT(*) OVER (PARTITION BY Sales.SalesOrderDetail.SalesOrderID) FROM Sales.SalesOrderDetail JOIN Sales.SalesOrderHeader ON Sales.SalesOrderDetail.SalesOrderID = Sales.SalesOrderHeader.SalesOrderID The split in percentages is now 6% / 94% and the profiler metrics are : Even more of a discrepancy. Estimates can be out with actuals for a whole host of reasons,  scalar UDF’s are a particular bug bear of mine and in-fact the cost of a udf call is entirely hidden inside the execution plan.  It always estimates to 0 (well, a very small number). Take for instance the following udf Create Function dbo.udfSumSalesForCustomer(@CustomerId integer) returns money as begin Declare @Sum money Select @Sum= SUM(SalesOrderHeader.TotalDue) from Sales.SalesOrderHeader where CustomerID = @CustomerId return @Sum end If we have two statements , one that fires the udf and another that doesn't: Select CustomerID from Sales.Customer order by CustomerID go Select CustomerID,dbo.udfSumSalesForCustomer(Customer.CustomerID) from Sales.Customer order by CustomerID The costs relative to batch is a 50/50 split, but the has to be an actual cost of firing the udf. Indeed profiler shows us : No where even remotely near 50/50!!!! Moving forward to window framing functionality in SQL Server 2012 the optimizer sees ROWS and RANGE ( see here for their functional differences) as the same ‘cost’ too SELECT SalesOrderDetailID,SalesOrderId, SUM(LineTotal) OVER(PARTITION BY salesorderid ORDER BY Salesorderdetailid RANGE unbounded preceding) from Sales.SalesOrderdetail go SELECT SalesOrderDetailID,SalesOrderId, SUM(LineTotal) OVER(PARTITION BY salesorderid ORDER BY Salesorderdetailid Rows unbounded preceding) from Sales.SalesOrderdetail By now it wont be a great display to show you the Profiler trace reads a *tiny* bit different. So moral of the story, Percentage relative to batch can give a rough ‘finger in the air’ measurement, but dont rely on it as fact.

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  • July, the 31 Days of SQL Server DMO’s – Day 19 (sys.dm_exec_query_stats)

    - by Tamarick Hill
    The sys.dm_exec_query_stats DMV is one of the most useful DMV’s out there when it comes to performance tuning. If you have been keeping up with this blog series this month, you know that I started out on Day 1 reviewing many of the DMV’s within the ‘exec’ namespace. I’m not sure how I missed this one considering how valuable it is, but hey, they say it’s better late than never right?? On Day 7 and Day 8 we reviewed the sys.dm_exec_procedure_stats and sys.dm_exec_trigger_stats respectively. This sys.dm_exec_query_stats DMV is very similar to these two. As a matter of fact, this DMV will return all of the information you saw in the other two DMV’s, but in addition to that, you can see stats for all queries that have cached execution plans on your server. You can even see stats for statements that are ran Ad-Hoc as long as they are still cached in the buffer pool. To better illustrate this DMV, let have a quick look at it: SELECT * FROM sys.dm_exec_query_stats As you can see, there is a lot of information returned from this DMV. I wont go into detail about each and every one of these columns, but I will touch on a few of them briefly. The first column is the ‘sql_handle’, which if you remember from Day 4 of our blog series, I explained how you can use this column to extract the actual SQL text that was executed. The next columns statement_start_offset and statement_end_offset provide you a way of extracting the exact SQL statement that was executed as part of a batch. The plan_handle column is used to extract the Execution plan that was used, which we talked about during Day 5 of this blog series. Later in the result set, you have columns to identify how many times a particular statement was executed, how much CPU time it used, how many reads/writes it performed, the duration, how many rows were returned, etc. These columns provide you with a solid avenue to begin your performance optimization. The last column I will touch on is the query_plan_hash column. A lot of times when you have Dynamic SQL running on your server, you have similar statements with different parameter values being passed in. Many times these types of statements will get similar execution plans and then a Binary hash value can be generated based on these similar plans. This query plan hash can be used to find the cost of all queries that have similar execution plans and then you can tune based on that plan to improve the performance of all of the individual queries. This is a very powerful way of identifying and tuning Ad-hoc statements that run on your server. As I stated earlier, this sys.dm_exec_query_stats DMV is a very powerful and recommended DMV for performance tuning. You are able to quickly identify statements that are running on your server and analyze their impact on system resources. Using this DMV to track down the biggest performance killers on your server will allow you to make the biggest gains once you focus your tuning efforts on those top offenders. For more information about this DMV, please see the below Books Online link: http://msdn.microsoft.com/en-us/library/ms189741.aspx Follow me on Twitter @PrimeTimeDBA

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  • optimize query: get al votes from user's item

    - by Toni Michel Caubet
    hi there! i did it my way because i'm very bad getting results from two tables... Basically, first i get all the id items that correspond to the user, and then i calculate the ratings of each item. But, there is two different types of object item, so i do this 2 times: show you: function votos_usuario($id){ $previa = "SELECT id FROM preguntas WHERE id_usuario = '$id'"; $r_previo = mysql_query($previa); $ids_p = '0, '; while($items_previos = mysql_fetch_array($r_previo)){ $ids_p .= $items_previos['id'].", "; //echo "ids pregunta usuario: ".$items_previos['id']."<br>"; } $ids = substr($ids_p,0,-2); //echo $ids; $consulta = "SELECT valor FROM votos_pregunta WHERE id_pregunta IN ( $ids )"; //echo $consulta; $resultado = mysql_query($consulta); $votos_preguntas = 0; while($voto = mysql_fetch_array($resultado)){ $votos_preguntas = $votos_preguntas + $voto['valor']; } $previa_r = "SELECT id FROM recetas WHERE id_usuario = '$id'"; $r_previo_r = mysql_query($previa_r); $ids_r = '0, '; while($items_previos_r = mysql_fetch_array($r_previo_r)){ $ids_r .= $items_previos_r['id'].", "; //echo "ids pregunta usuario: ".$items_previos['id']."<br>"; } $ids = substr($ids_r,0,-2); $consulta_b = "SELECT valor FROM votos_receta WHERE id_receta IN ( $ids )"; //echo $consulta; $resultado_b = mysql_query($consulta_b); $votos_recetas = 0; while($voto_r = mysql_fetch_array($resultado_b)){ $votos_recetas = $votos_recetas + $voto_r['valor']; } $total = $votos_preguntas + $votos_recetas; return $total; } As you can si this is two much.. O(n^2) Feel like thinking? thanks!

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  • Query not returning rows in a table that don't have corresponding values in another [associative] ta

    - by Obay
    I have Table: ARTICLES ID | CONTENT --------------- 1 | the quick 2 | brown fox 3 | jumps over 4 | the lazy Table: WRITERS ID | NAME ---------- 1 | paul 2 | mike 3 | andy Table: ARTICLES_TO_WRITERS ARTICLE_ID | WRITER_ID ----------------------- 1 | 1 2 | 2 3 | 3 To summarize, article 4 has no writer. So when I do a "search" for articles with the word "the": SELECT a.id, a.content, w.name FROM articles a, writers w, articles_to_writers atw WHERE a.id=atw.article_id AND w.id=atw.writer_id AND content LIKE '%the%' article 4 does not show up in the result: ID | CONTENT | NAME ----------------------- 1 | the quick | paul How do I make article 4 still appear in the results even though it has no writers?

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  • Optimize MYSQL Query with Order by

    - by Victor
    Hello, I have seen mysql queries with order by runs slow. Is there any specific way to optimize queries which use order by ? Queries without order by run very fast but with order by its always runs slow. if any one suggest any thing on this as general solutions. Thank You

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  • How to optimize this user ranking query

    - by James Simpson
    I have 2 databases (users, userRankings) for a system that needs to have rankings updated every 10 minutes. I use the following code to update these rankings which works fairly well, but there is still a full table scan involved which slows things down with a few hundred thousand users. mysql_query("TRUNCATE TABLE userRankings"); mysql_query("INSERT INTO userRankings (userid) SELECT id FROM users ORDER BY score DESC"); mysql_query("UPDATE users a, userRankings b SET a.rank = b.rank WHERE a.id = b.userid"); In the userRankings table, rank is the primary key and userid is an index. Both tables are MyISAM (I've wondered if it might be beneficial to make userRankings InnoDB).

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  • Query Tuning Mastery at PASS Summit 2012: The Video

    - by Adam Machanic
    An especially clever community member was kind enough to reverse-engineer the video stream for me, and came up with a direct link to the PASS TV video stream for my Query Tuning Mastery: The Art and Science of Manhandling Parallelism talk, delivered at the PASS Summit last Thursday. I'm not sure how long this link will work , but I'd like to share it for my readers who were unable to see it in person or live on the stream. Start here. Skip past the keynote, to the 149 minute mark. Enjoy!...(read more)

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  • Query Tuning Mastery at PASS Summit 2012: The Video

    - by Adam Machanic
    An especially clever community member was kind enough to reverse-engineer the video stream for me, and came up with a direct link to the PASS TV video stream for my Query Tuning Mastery: The Art and Science of Manhandling Parallelism talk, delivered at the PASS Summit last Thursday. I'm not sure how long this link will work , but I'd like to share it for my readers who were unable to see it in person or live on the stream. Start here. Skip past the keynote, to the 149 minute mark. Enjoy!...(read more)

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  • Query Tuning Mastery at PASS Summit 2012: The Demos

    - by Adam Machanic
    For the second year in a row, I was asked to deliver a 500-level "Query Tuning Mastery" talk in room 6E of the Washington State Convention Center, for the PASS Summit. ( Here's some information about last year's talk, on workspace memory. ) And for the second year in a row, I had to deliver said talk at 10:15 in the morning, in a room used as overflow for the keynote, following a keynote speaker that didn't stop speaking on time. Frustrating! Last Thursday, after very, very quickly setting up and...(read more)

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  • Converting sql query to EF query - nested query in from

    - by vdh_ant
    Hey guys Just wondering how the following sql query would look in linq for Entity Framework... SELECT KPI.* FROM KeyPerformanceIndicator KPI INNER JOIN ( SELECT SPP.SportProgramPlanId FROM SportProgramPlan PSPP INNER JOIN SportProgramPlan ASPP ON (PSPP.SportProgramPlanId = @SportProgramPlanId AND PSPP.StartDate >= ASPP.StartDate AND PSPP.EndDate <= ASPP.EndDate ) AS SPP ON KPI.SportProgramPlanId = SPP.SportProgramPlanId Cheers Anthony

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  • Character Stats and Power

    - by Stephen Furlani
    I'm making an RPG game system and I'm having a hard time deciding on doing detailed or abstract character statistics. These statistics define the character's natural - not learned - abilities. For example: Mass Effect: 0 (None that I can see) X20 (Xtreme Dungeon Mastery): 1 "STAT" Diablo: 4 "Strength, Magic, Dexterity, Vitality" Pendragon: 5 "SIZ, STR, DEX, CON, APP" Dungeons & Dragons (3.x, 4e): 6 "Str, Dex, Con, Wis, Int, Cha" Fallout 3: 7 "S.P.E.C.I.A.L." RIFTS: 8 "IQ, ME, MA, PS, PP, PE, PB, Spd" Warhammer Fantasy Roleplay (1st ed?): 12-ish "WS, BS, S, T, Ag, Int, WP, Fel, A, Mag, IP, FP" HERO (5th ed): 14 "Str, Dex, Con, Body, Int, Ego, Pre, Com, PD, ED, Spd, Rec, END, STUN" The more stats, the more complex and detailed your character becomes. This comes with a trade-off however, because you usually only have limited resources to describe your character. D&D made this infamous with the whole min/max-ing thing where strong characters were typically not also smart. But also, a character with a high Str typically also has high Con, Defenses, Hit Points/Health. Without high numbers in all those other stats, they might as well not be strong since they wouldn't hold up well in hand-to-hand combat. So things like that force trade-offs within the category of strength. So my original (now rejected) idea was to force players into deciding between offensive and defensive stats: Might / Body Dexterity / Speed Wit / Wisdom Heart Soul But this left some stat's without "opposites" (or opposites that were easily defined). I'm leaning more towards the following: Body (Physical Prowess) Mind (Mental Prowess) Heart (Social Prowess) Soul (Spiritual Prowess) This will define a character with just 4 numbers. Everything else gets based off of these numbers, which means they're pretty important. There won't, however, be ways of describing characters who are fast, but not strong or smart, but absent minded. Instead of defining the character with these numbers, they'll be detailing their character by buying skills and powers like these: Quickness Add a +2 Bonus to Body Rolls when Dodging. for a character that wants to be faster, or the following for a big, tough character Body Building Add a +2 Bonus to Body Rolls when Lifting, Pushing, or Throwing objects. [EDIT - removed subjectiveness] So my actual questions is what are some pitfalls with a small stat list and a large amount of descriptive powers? Is this more difficult to port cross-platform (pen&paper, PC) for example? Are there examples of this being done well/poorly? Thanks,

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  • over reporting in google analytics - social media stats

    - by colmcq
    I have a client and their traffic from social media reads thus: 80% from facebook 1% from Twitter This suggestsd they are not exploiting twitter at all and this was in my presentation but my boss took it out claiming twitter stats are under reported in google analytics. I can't substantiate this claim and wonder where she got this idea from. Can anyone shed light on this? Are my stats wrong and should I disregard these figures? but 80-1 seems like one hell of an under report! thanks c

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  • CCNet and .Net 4.0

    - by Pino
    Could not load file or assembly 'System.Data' or one of its dependencies. An attempt was made to load a program with an incorrect format We have just upgraded one of our projects to .Net 4.0 and have re-configured our build server (Cruise Control .Net). Anyone help with the above error? I have included more trace below. > debug: > > [copy] Copying 1 file to 'C:\Builds\SilverChip\Working\sc.website\web.config'. > [copy] Copying 1 file to 'C:\Builds\SilverChip\Working\sc.admin\web.config'. > [copy] Copying 1 file to 'C:\Builds\SilverChip\Working\sc.website\bin\Intelligencia.UrlRewriter.dll'. > [copy] Copying 1 file to 'C:\Builds\SilverChip\Working\sc.website\bin\UrlRewritingNet.UrlRewriter.dll'. > [exec] Microsoft (R) Build Engine Version 4.0.30319.1 > [exec] [Microsoft .NET Framework, Version 4.0.30319.1] > [exec] Copyright (C) Microsoft Corporation 2007. All rights > reserved. > [exec] > [exec] Build started 11/05/2010 12:02:16. > [exec] Project "C:\Builds\SilverChip\Working\Silverchip.sln" > on node 1 (default targets). > [exec] ValidateSolutionConfiguration: > [exec] Building solution configuration "Debug|Any CPU". > [exec] Project "C:\Builds\SilverChip\Working\Silverchip.sln" > (1) is building > "C:\Builds\SilverChip\Working\sc.lib\sc.lib.csproj" > (2) on node 1 (default targets). > [exec] CoreCompile: > [exec] Skipping target "CoreCompile" because all output files > are up-to-date with respect to the > input files. > [exec] _CopyAppConfigFile: > [exec] Skipping target "_CopyAppConfigFile" because all > output files are up-to-date with > respect to the input files. > [exec] CopyFilesToOutputDirectory: > [exec] sc.lib -> C:\Builds\SilverChip\Working\sc.lib\bin\Debug\sc.lib.dll > [exec] Done Building Project "C:\Builds\SilverChip\Working\sc.lib\sc.lib.csproj" > (default targets). > [exec] Project "C:\Builds\SilverChip\Working\Silverchip.sln" > (1) is building > "C:\Builds\SilverChip\Working\sc_admin.metaproj" > (3) on node 1 (default targets). > [exec] Build: > [exec] Copying file from "C:\Builds\SilverChip\Working\sc.lib\bin\Debug\sc.lib.dll" > to "sc.admin\\Bin\sc.lib.dll". > [exec] Copying file from "C:\Builds\SilverChip\Working\sc.lib\bin\Debug\SubSonic.Core.dll" > to "sc.admin\\Bin\SubSonic.Core.dll". > [exec] Copying file from "C:\Builds\SilverChip\Working\sc.lib\bin\Debug\sc.lib.pdb" > to "sc.admin\\Bin\sc.lib.pdb". > [exec] C:\Windows\Microsoft.NET\Framework\v4.0.30319\aspnet_compiler.exe > -v /sc.admin -p sc.admin\ -u -f -d PrecompiledWeb\sc.admin\ > [exec] ASPNETCOMPILER : error ASPCONFIG: Could not load file or > assembly 'System.Data' or one of its > dependencies. An attempt was made to > load a program with an incorrect > format. > [C:\Builds\SilverChip\Working\sc_admin.metaproj] > [exec] Done Building Project "C:\Builds\SilverChip\Working\sc_admin.metaproj" > (default targets) -- FAILED. > [exec] Project "C:\Builds\SilverChip\Working\Silverchip.sln" > (1) is building > "C:\Builds\SilverChip\Working\sc_website.metaproj" > (4) on node 1 (default targets). > [exec] Build: > [exec] Copying file from "C:\Builds\SilverChip\Working\sc.lib\bin\Debug\sc.lib.dll" > to "sc.website\\Bin\sc.lib.dll". > [exec] Copying file from "C:\Builds\SilverChip\Working\sc.lib\bin\Debug\SubSonic.Core.dll" > to > "sc.website\\Bin\SubSonic.Core.dll". > [exec] Copying file from "C:\Builds\SilverChip\Working\sc.lib\bin\Debug\sc.lib.pdb" > to "sc.website\\Bin\sc.lib.pdb". > [exec] C:\Windows\Microsoft.NET\Framework\v4.0.30319\aspnet_compiler.exe > -v /sc.website -p sc.website\ -u -f -d PrecompiledWeb\sc.website\ > [exec] ASPNETCOMPILER : error ASPCONFIG: Could not load file or > assembly 'System.Data' or one of its > dependencies. An attempt was made to > load a program with an incorrect > format. > [C:\Builds\SilverChip\Working\sc_website.metaproj] > [exec] Done Building Project "C:\Builds\SilverChip\Working\sc_website.metaproj" > (default targets) -- FAILED. > [exec] Done Building Project "C:\Builds\SilverChip\Working\Silverchip.sln" > (default targets) -- FAILED. > [exec] > [exec] Build FAILED. > [exec] > [exec] "C:\Builds\SilverChip\Working\Silverchip.sln" > (default target) (1) -> > [exec] "C:\Builds\SilverChip\Working\sc_admin.metaproj" > (default target) (3) -> > [exec] (Build target) -> > [exec] ASPNETCOMPILER : error ASPCONFIG: Could not load file > or assembly 'System.Data' or one of > its dependencies. An attempt was made > to load a program with an incorrect > format. > [C:\Builds\SilverChip\Working\sc_admin.metaproj] > [exec] > [exec] > [exec] "C:\Builds\SilverChip\Working\Silverchip.sln" > (default target) (1) -> > [exec] "C:\Builds\SilverChip\Working\sc_website.metaproj" > (default target) (4) -> > [exec] ASPNETCOMPILER : error ASPCONFIG: Could not load file > or assembly 'System.Data' or one of > its dependencies. An attempt was made > to load a program with an incorrect > format. > [C:\Builds\SilverChip\Working\sc_website.metaproj] > [exec] > [exec] 0 Warning(s) > [exec] 2 Error(s) > [exec]

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  • Python: Which encoding is used for processing sys.argv?

    - by EOL
    What encoding are the elements of sys.argv in, in Python? are they encoded with the sys.getdefaultencoding() encoding? sys.getdefaultencoding(): Return the name of the current default string encoding used by the Unicode implementation. PS: As pointed out in some of the answers, sys.stdin.encoding would indeed be a better guess. I would love to see a definitive answer to this question, though, with pointers to solid sources! PPS: As Wim pointed out, Python 3 solves this issue by putting str objects in sys.argv (if I understand correctly). The question remains open for Python 2.x, though. Under Unix, the LC_CTYPE environment variable seems to be the correct thing to check, no? What should be done with Windows (so that sys.argv elements are correctly interpreted whatever the console)?

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  • Streaming output with commons-exec?

    - by Stefan Kendall
    Can anyone give me an example of how to stream the output of an external program executed with DefaultExecutor? I'm not finding any documentation describing how to do this. My external process will run for several hours, so just grabbing all output data isn't feasible; it must be streamed.

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  • Who owns a php exec tar extracted file?

    - by Ken
    As far as file permissions are concerned, when you use a php script to unzip a tar file, who is the "owner" user of the files created? I'm wondering if its my ftp user because I uploaded the script file? Or does apache own the file? I know their are flags to be set to preserve the original permissions which I don't want (files where created and archived by someone else). I want my user to be the creater/owner of the files.

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  • PHP exec - missing output

    - by japanitrat
    Hi there, I am currently trying to get SoX working through PHP. It all works so far, but I don't get the output back. I've already read that one might route stderr also to the output with "2&1" .. the problem is, this doesn't seem to work on windows machines. any other ideas?

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  • July, the 31 Days of SQL Server DMO’s – Day 28 (sys.dm_db_stats_properties)

    - by Tamarick Hill
    The sys.dm_db_stats_properties Dynamic Management Function returns information about the statistics that are currently on your database objects. This function takes two parameters, an object_id and a stats_id. Let’s have a look at the result set from this function against the AdventureWorks2012.Sales.SalesOrderHeader table. To obtain the object_id and stats_id I will use a CROSS APPLY with the sys.stats system table. SELECT sp.* FROM sys.stats s CROSS APPLY sys.dm_db_stats_properties(s.object_id, s.Stats_id) sp WHERE sp.object_id = object_id('Sales.SalesOrderHeader') The first two columns returned by this function are the object_id and the stats_id columns. The next column, ‘last_updated’, gives you the date and the time that a particular statistic was last updated. The next column, ‘rows’, gives you the total number of rows in the table as of the last statistic update date. The ‘rows_sampled’ column gives you the number of rows that were sampled to create the statistic. The ‘steps’ column represents the number of specific value ranges from the statistic histogram. The ‘unfiltered_rows’ column represents the number of rows before any filters are applied. If a particular statistic is not filtered, the ‘unfiltered_rows’ column will always equal the ‘rows’ column. Lastly we have the ‘modification_counter’ column which represents the number of modification to the leading column in a given statistic since the last time the statistic was updated. Probably the most important column from this Dynamic Management Function is the ‘last_updated’ column. You want to always ensure that you have accurate and updated statistics on your database objects. Accurate statistics are vital for the query optimizer to generate efficient and reliable query execution plans. Without accurate and updated statistics, the performance of your SQL Server would likely suffer. For more information about this Dynamic Management Function, please see the below Books Online link: http://msdn.microsoft.com/en-us/library/jj553546.aspx Folllow me on Twitter @PrimeTimeDBA

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  • When was sys.dm_os_wait_stats last cleared?

    - by SQLOS Team
    The sys.dm_os_wait_stats DMV provides essential metrics for diagnosing SQL Server performance problems. Returning incrementally accumulating information about all the completed waits encountered by executing threads it is a useful way to identify bottlenecks such as IO latency issues or waits on locks. The counters are reset each time SQL server is restarted, or when the following command is run: DBCC SQLPERF ('sys.dm_os_wait_stats', CLEAR); To make sense out of these wait values you need to know how they change over time. Suppose you are asked to troubleshoot a system and you don't know when the wait stats were last zeroed. Is there any way to find the elapsed time since this happened? If the wait stats were not cleared using the DBCC SQLPERF command then you can simply correlate the stats with the time SQL Server was started using the sqlserver_start_time column introduced in SQL Server 2008 R2: SELECT sqlserver_start_time from sys.dm_os_sys_info However how do you tell if someone has run DBCC SQLPERF ('sys.dm_os_wait_stats', CLEAR) since the server was started, and if they did, when? Without this information the initial, or historical, wait_stats have less value until you can measure deltas over time. There is a way to at least estimate when the stats were last cleared, by using the wait stats themselves and choosing a thread that spends most of its time sleeping. A good candidate is the SQL Trace incremental flush task, which mostly sleeps (in 4 second intervals) and in between it attempts to flush (if there are new events – which is rare when only default trace is running) – so it pretty much sleeps all the time. Hence the time it has spent waiting is very close to the elapsed time since the counter was reset. Credit goes to Ivan Penkov in the SQLOS dev team for suggesting this. Here's an example (excuse formatting): 144 seconds after the server was started: select top 10 wait_type, wait_time_ms from sys.dm_os_wait_stats order by wait_time_ms desc wait_type                                                               wait_time_ms--------------------------------------------------------------------------------------------------------------- XE_DISPATCHER_WAIT                                      242273LAZYWRITER_SLEEP                                          146010LOGMGR_QUEUE                                                145412DIRTY_PAGE_POLL                                             145411XE_TIMER_EVENT                                               145216REQUEST_FOR_DEADLOCK_SEARCH             145194SQLTRACE_INCREMENTAL_FLUSH_SLEEP    144325SLEEP_TASK                                                        73359BROKER_TO_FLUSH                                           73113PREEMPTIVE_OS_AUTHENTICATIONOPS       143 (10 rows affected) Reset: DBCC SQLPERF('sys.dm_os_wait_stats', CLEAR)" DBCC execution completed. If DBCC printed error messages, contact your system administrator. After 8 seconds: select top 10 wait_type, wait_time_ms from sys.dm_os_wait_stats order by wait_time_ms desc wait_type                                                                 wait_time_ms--------------------------------------------------------------------------------------------------------------------- REQUEST_FOR_DEADLOCK_SEARCH              10013LAZYWRITER_SLEEP                                           8124SQLTRACE_INCREMENTAL_FLUSH_SLEEP     8017LOGMGR_QUEUE                                                 7579DIRTY_PAGE_POLL                                              7532XE_TIMER_EVENT                                                5007BROKER_TO_FLUSH                                            4118SLEEP_TASK                                                         3089PREEMPTIVE_OS_AUTHENTICATIONOPS        28SOS_SCHEDULER_YIELD                                   27 (10 rows affected)   After 12 seconds: select top 10 wait_type, wait_time_ms from sys.dm_os_wait_stats order by wait_time_ms desc wait_type                                                                  wait_time_ms------------------------------------------------------------------------------------------------------ REQUEST_FOR_DEADLOCK_SEARCH               15020LAZYWRITER_SLEEP                                            14206LOGMGR_QUEUE                                                  14036DIRTY_PAGE_POLL                                               13973SQLTRACE_INCREMENTAL_FLUSH_SLEEP      12026XE_TIMER_EVENT                                                 10014SLEEP_TASK                                                          7207BROKER_TO_FLUSH                                             7207PREEMPTIVE_OS_AUTHENTICATIONOPS         57SOS_SCHEDULER_YIELD                                     28 (10 rows affected) It may not be accurate to the millisecond, but it can provide a useful data point, and give an indication whether the wait stats were manually cleared after startup, and if so approximately when. - Guy     Originally posted at http://blogs.msdn.com/b/sqlosteam/

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  • SQL SERVER – Denali Feature – Zoom Query Editor

    - by pinaldave
    SQL Server next version ‘Denali’ is coming up with very neat feature which can be used while presentations, group discussion or for people who prefers large fonts. I have increased the font size to 400 percentage and for the same reason they are very large. You can adjust the font size which is convenient to you. One more reason to go for next version of SQL Server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology

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  • Adding an LOV to a query parameter (executeWithParams)

    - by shay.shmeltzer
    I showed in the past how you can use the executeWithParams operation to build your own query page to filter a view object to show specific rows. I also showed how you can make the parameter fields display as drop down lists of values (selectOneChoice). However this week someone asked me if you can have those parameter fields use the advanced LOV component. Well if you just try and drag the parameter over, you'll see that the LOV option is not there as a drop option. But with a little bit of hacking around you can achieve this. (without actual Java coding). Here is a quick demo:

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  • How can I join this 2 queries?(A select query with join and An unpivot query)

    - by MANG KANOR
    Here are my two queries SELECT EWND.Position, NKey = CASE WHEN ISNULL(Translation.Name, '') = '' THEN EWND.Name ELSE Translation.Name END, Unit = EW_N_DEF.Units FROM EWND INNER JOIN EW_N_DEF ON EW_N_DEF.Nutr_No = EWND.Nutr_No LEFT JOIN Translation ON Translation.CodeMain = EWND.Nutr_no WHERE Translation.CodeTrans = 1 ORDER BY EWND.Position And this is the unpivot one SELECT * FROM (SELECT N1,N2,N3,N4,N5,N6,N7,N8,N9,N10,N11,N12,N13,N14,N15,N16,N17,N18,N19,N20,N21,N22,N23,N24,N25,N26,N27,N28,N29,N30,N31,N32,N33,N34 FROM EWNVal WHERE Code=6035) Test UNPIVOT (Value FOR NUTCODE IN (N1,N2,N3,N4,N5,N6,N7,N8,N9,N10,N11,N12,N13,N14,N15,N16,N17,N18,N19,N20,N21,N22,N23,N24,N25,N26,N27,N28,N29,N30,N31,N32,N33,N34) )AS test Both Queries put out same number of rows but not columns, Is it possible to join this two? I tried the union but it has problems that I cant solve Thanks in advance!

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