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  • SQL SERVER – New Look for CodePlexProject – Hosting for Open Source Software

    - by pinaldave
    Codeplex is my favorite site. CodePlex is Microsoft’s free open source project hosting site. You can create projects to share with the world, collaborate with others on their projects, and download open source software. It is great place to find so many open source project available to explore. All the softwares are free and open source. I often go there at intervals to check what is new in SQL Server field as well on other technologies. Yesterday when I visited it, I had nice surprise as it has total makeover and looks very decent as well elegant at the same time. I have noticed that when I talk about Codeplex is user community, not everybody knows about it. The quickest way I explain what is codeplex is that I start naming few of the projects which are available there and suddenly I start noticing a few hands going up knowing the projects. This is indirect way to prove that many of us know CodePlex usability but do not pay special attention to what it is actually. Let me name a few popular projects of the CodePlex here. SQL Server Sample Database [link] Image Resizer for Windows [link] Ajax Control Toolkit [link] Skype Voice Changer [link] Silverlight Toolkit [link] Windows 7 USB/DBD Download Tool [link] Orchard Project [link] There are very interesting SQL Server projects available on Codeplex as well. I am listing few of them here for reference in listed in no particular order. SQL Server Sample Database [link] SQL Server Compact ToolBox [link] Microsoft Drivers for PHP for SQL Server [link] Internals Viewer for SQL Server [link] SQL Server Spatial Tooks [link] SQL Monitor – managing sql server performance [link] SQL Server 2008 Extended Events SSMS Addin [link] How many of above mentioned project have you come across earlier? Leave a comment it will be interesting to know what our community is familiar with. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Where is a good place to start to learn about custom caching in .Net

    - by John
    I'm looking to make some performance enhancements to our site, but I'm not sure exactly where to begin. We have some custom object caching, but I think that we can do better. Our Business We aggregate news stories on a news type of web site. We get approximately 500-1000 new stories per week. We have index pages that show various lists of the items and details pages that show the individual stories. Our Current Use case: Getting an Individual Story User makes a request The Data Access Layer(DAL) checks to see if the item is in cache and if item is fresh (15 minutes). If the item is not in cache or is not fresh, retrieve the item from SQL Server, save to cache and return to user. Problems with this approach The pull nature of caching means that users have to pay the waiting cost every time that the cache is refreshed. Once a story is published, it changes infrequently and I think that we should replace the pull model with something better. My initial thoughts My initial thought is that stories should ALL be stored locally in some type of dictionary. (Cache or is there another, better way?). If the story is not found, then make a trip to the database, update the local dictionary and send the item back. Since there may be occasional updates to stories, this should be an entirely process from the user. I watched a video by Brent Ozar, How StackOverflow Scales SQL Server, in which Brent states "the fastest database query is the one that you don't make". Where do I start? At this point, I don't know exactly what the solution is. Is it caching? Is there a better way of using local storage? Do I use a Dictionary, OrderedDictionary, List ? It seems daunting and I'm just looking for some good starting points to learn more about how to do this type of optimization.

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  • Perfomance of 8 bit operations on 64 bit architechture

    - by wobbily_col
    I am usually a Python / Database programmer, and I am considering using C for a problem. I have a set of sequences, 8 characters long with 4 possible characters. My problem involves combining sets of these sequences and filtering which sets match a criteria. The combinations of 5 run into billions of rows and takes around an hour to run. So I can represent each sequence as 2 bytes. If I am working on a 64 bit architechture will I gain any advantage by keeping these data structures as 2 bytes when I generate the combinations, or will I be as well storing them as 8 bytes / double ? (64 bit = 8 x 8) If I am on a 64 bit architecture, all registers will be 64 bit, so in terms of operations that shouldn´t be any faster (please correct me if I am wrong). Will I gain anything from the smaller storage requirements - can I fit more combinations in memory, or will they all take up 64 bits anyway? And finally, am I likley to gain anything coding in C. I have a first version, which stores the sequence as a small int in a MySQL database. It then self joins the tabe to itself a number of times in order to generate all the possible combinations. The performance is acceptable, depending on how many combinations are generated. I assume the database must involve some overhead.

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  • Is there a better way to consume an ASP.NET Web API call in an MVC controller?

    - by davidisawesome
    In a new project I am creating for my work I am creating a fairly large ASP.NET Web API. The api will be in a separate visual studio solution that also contains all of my business logic and database interactions, Model classes as well. In the test application I am creating (which is asp.net mvc4), I want to be able to hit an api url I defined from the control and cast the return JSON to a Model class. The reason behind this is that I want to take advantage of strongly typing my views to a Model. This is all still in a proof of concept stage, so I have not done any performance testing on it, but I am curious if what I am doing is a good practice, or if I am crazy for even going down this route. Here is the code on the client controller: public class HomeController : Controller { protected string dashboardUrlBase = "http://localhost/webapi/api/StudentDashboard/"; public ActionResult Index() //This view is strongly typed against User { //testing against Joe Bob string adSAMName = "jBob"; WebClient client = new WebClient(); string url = dashboardUrlBase + "GetUserRecord?userName=" + adSAMName; //'User' is a Model class that I have defined. User result = JsonConvert.DeserializeObject<User>(client.DownloadString(url)); return View(result); } . . . } If I choose to go this route another thing to note is I am loading several partial views in this page (as I will also do in subsequent pages). The partial views are loaded via an $.ajax call that hits this controller and does basically the same thing as the code above: Instantiate a new WebClient Define the Url to hit Deserialize the result and cast it to a Model Class. So it is possible (and likely) I could be performing the same actions 4-5 times for a single page. Is there a better method to do this that will: Let me keep strongly typed views. Do my work on the server rather than on the client (this is just a preference since I can write C# faster than I can write javascript).

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  • How to diagnose Ubuntu CPU spikes / IO wait?

    - by Jeff Welling
    I'm using Ubuntu and every couple minutes it goes unresponsive for a half second to a full second, which isn't normally a problem but makes trying to code extremely frustrating when your trying to hit backspace or navigate the code and nothing is happening. The problem is, the freezes are so brief that top doesn't have time to show me what is spiking the CPU (assuming something is, but I don't know what else could cause this). Does anyone know how to troubleshoot this performance issue? Edit: I've tried login in with Gnome Classic (No Effects) instead of Unity but it still freezes up every once in awhile. Edit: The CPU graph doesn't seem to be showing any actual spikes so it seems you were right and my original diagnosis of CPU spikes being the problem was incorrect, I now suspect IO wait. I don't recall this happening for the brief few weeks I had Windows 7 Starter running on it though, which leads me to believe it isn't (just?) the hardware.. is there anything I can tweak to improve this? I'm using an Acer Aspire One D257, with Ubuntu 11.10. Edit: Output of dmesg is at http://paste.ubuntu.com/1060054/ and kern.log is at http://paste.ubuntu.com/1060055/

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  • Ubuntu Slow - What architecture does the Windows Installer install?

    - by Benjamin Yep
    I feel absolutely limited by using Windows, and I need to switch to a Unix environment. I once installed Red Hat on my lappie (screen + external monitor setup; 4GB ram; x64; runs fast) and it worked fine, but I saw that the computer cluster that is the birthplace of my unix knowledge switched to Ubuntu, so naturally I follow. To the point. When I installed Ubuntu onto my machine via the Windows Installer, it ran quite slow. Opening Firefox takes about 8-9 seconds, it freezes up often, unable to handle its own background processes. I saw in a thread that, perhaps, it is running slow because the Windows Installer is installing an x64 version. Of course, my computer has had no performance issues in the past(except that time with the trojans but you know, know one is perfect ;) ) Anyways, I uninstalled Ubuntu, freeing up the max allocated memory it took up, and continue to be sad, trapped in my MS world with only a buggy Cygwin, any assistance is greatly appreciated! :) Thanks ~Ben

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  • ATI Radeon 5800 series dual monitor unity not 3D accelerated

    - by Victor S
    When I had a single monitor setup, without Xinerama, with my current setup of Ubuntu 11.10, ATI 5800 series card, Unity showed transparencies, shadows, etc. (although graphics was reported as 'Standard' in the control/settings panel). Having switched to a dual monitor setup, dell 24" UltraSharp and a smaller Acer monitor, Unity shows only as 2d, even though I'm not loggin in to that display manager. WebGL performance is very sluggish, I'm getting the impression that the processor is doing all the work and the card isn't even accessible even though the drivers are installed (from the ubuntu repository, I did not compile custom drivers). Any tips on how to enable full 3D accelerationn and video card support. Here is my xorg.conf file: Section "Monitor" Identifier "0-DFP3" Option "VendorName" "ATI Proprietary Driver" Option "ModelName" "Generic Autodetecting Monitor" Option "DPMS" "true" Option "PreferredMode" "1680x1050" Option "TargetRefresh" "60" Option "Position" "0 0" Option "Rotate" "normal" Option "Disable" "false" EndSection Section "Monitor" Identifier "0-DFP4" Option "VendorName" "ATI Proprietary Driver" Option "ModelName" "Generic Autodetecting Monitor" Option "DPMS" "true" Option "PreferredMode" "1920x1200" Option "TargetRefresh" "60" Option "Position" "0 0" Option "Rotate" "normal" Option "Disable" "false" EndSection Section "Screen" Identifier "Default Screen" DefaultDepth 24 SubSection "Display" EndSubSection EndSection Section "Screen" Identifier "amdcccle-Screen[1]-0" Device "amdcccle-Device[1]-0" DefaultDepth 24 SubSection "Display" Viewport 0 0 Depth 24 EndSubSection EndSection Section "Screen" Identifier "amdcccle-Screen[1]-1" Device "amdcccle-Device[1]-1" DefaultDepth 24 SubSection "Display" Viewport 0 0 Depth 24 EndSubSection EndSection Section "Module" Load "glx" EndSection Section "ServerLayout" Identifier "amdcccle Layout" Screen 0 "amdcccle-Screen[1]-0" 0 0 Screen "amdcccle-Screen[1]-1" 1920 0 EndSection Section "Device" Identifier "amdcccle-Device[1]-0" Driver "fglrx" Option "Monitor-DFP4" "0-DFP4" BusID "PCI:1:0:0" EndSection Section "Device" Identifier "amdcccle-Device[1]-1" Driver "fglrx" Option "Monitor-DFP3" "0-DFP3" BusID "PCI:1:0:0" Screen 1 EndSection Section "ServerFlags" Option "Xinerama" "on" EndSection More info: fglrxinfo display: :0 screen: 0 OpenGL vendor string: ATI Technologies Inc. OpenGL renderer string: ATI Radeon HD 5800 Series OpenGL version string: 4.1.11005 Compatibility Profile Context

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  • Why is rvalue write in shared memory array serialised?

    - by CJM
    I'm using CUDA 4.0 on a GPU with computing capability 2.1. One of my device functions is the following: device void test(int n, int* itemp) // itemp is shared memory pointer { const int tid = threadIdx.x; const int bdim = blockDim.x; int i, j, k; bool flag = 0; itemp[tid] = 0; for(i=tid; i<n; i+=bdim) { // { code that produces some values of "flag" } } itemp[tid] = flag; } Each thread is checking some conditions and producing a 0/1 flag. Then each thread is writing flag at the tid-th location of a shared int array. The write statement "itemp[tid] = flag;" gets serialized -- though "itemp[tid] = 0;" is not. This is causing huge performance lag which technically should not be there -- I want to avoid it. Please help.

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  • The clock problem - to if or not to if?

    - by trejder
    Let's say, we have a simple digital clock. To "power" it, we use a routine executed every second. We update seconds part in it. But, what about minutes and hours part? What is better / more professional / offers better performance: Ignore all checking and update hour, minute and seconds part each time, every second. Use if + a variable for checking, if 60 (or 3600) seconds passed and update minute / hour part only at that precise moments. This leads us to a question, what is better -- unnecessary drawings (first approach) or extra ifs? I've just spotted a Javascript digital clock, one of millions similar on one of billions pages. And I noticed that all three parts (hours, minutes and seconds) are updated every second, though first changes its value only once per 3600 seconds and second once per 60 seconds. I'm not to experienced developer, so I might me wrong. But everything, what I've learnt up until now, tells me, that if are far better then executing drawing / refreshing sequences only to draw the same content.

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  • Cuda driver, CPU/GPU performances issue

    - by elect
    I implemented a RNS Montgomery exponentiation in Cuda and on cpu for comparison. Everything nice everything fine. It runs on just one SM. However I am going to tell you some strange regression in both cpu/gpu performances. During the devoloping, about two month ago, I was using Cuda 5 preview on Ubuntu 11.04 64b. In this time, I reach the following performances: cpu 460ms gpu 120ms Then one day when I turn on the pc, the graphical environment didnt start. I dont know which was the problem, however I switched to the console and installed again the Cuda driver. At the following boot performances changed: cpu 310ms gpu 80ms I was like Q.Q...uhm ok, nice to see this, but I was wondering how that could be possible However, I went then in holiday for 10 days and I continued developing and optimizing on my notebook (but not the same part of the code, some additional stuff) When I was back, I just updated the source files, and performances came back to 460/120ms.. I couldnt believe it, I tried to install Cuda 5 RC, updating the video driver too... nothing changed... I checked Debug/Release, Cuda computability, but the problem seems being somewhere else.. Looking around the net I found this, I am pretty sure it must have something to do with the driver, because the performance change affected both cpu and gpu Do you have some tips/ideas/suggestions?

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  • My first blog post…

    - by steveh99999
    I’ve been meaning to start a blog for a while now, (OK, for several years…..) - finally now, here it begins First post, something really simple but, a wise-man once told me about the best way to improve SQL server performance. Store Less Data. That's it.. that's all there is to it... Over the years, I've seen the following :- -  a 200Gb database which held 3 days data. Once business requirements changed, we were able to hold only 1 days data in this database. -  a table developed by DBAs to hold application table cardinality information - that information was collected at 2 hour intervals every day for 7 years ! After 7 years the DBA space-info table had become the largest table in the database - 60 million rows !  It was a simple change to remove alot of the historical intra-day data and change the schedule to run only once per evening. Suddenly that table held 6 million rows instead of 60 million.... - lots of backup and restore history held in msdb. See this post by Brent Ozar for more details on this issue. Imagine how much faster the backups, DBCC Checks and reindexes ran when the above 3 changes were implemented ?   How often do you review your big databases \ tables to see if you’re actually holding only data that is really required by the business ?

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  • Why is quicksort better than other sorting algorithms in practice?

    - by Raphael
    This is a repost of a question on cs.SE by Janoma. Full credits and spoils to him or cs.SE. In a standard algorithms course we are taught that quicksort is O(n log n) on average and O(n²) in the worst case. At the same time, other sorting algorithms are studied which are O(n log n) in the worst case (like mergesort and heapsort), and even linear time in the best case (like bubblesort) but with some additional needs of memory. After a quick glance at some more running times it is natural to say that quicksort should not be as efficient as others. Also, consider that students learn in basic programming courses that recursion is not really good in general because it could use too much memory, etc. Therefore (and even though this is not a real argument), this gives the idea that quicksort might not be really good because it is a recursive algorithm. Why, then, does quicksort outperform other sorting algorithms in practice? Does it have to do with the structure of real-world data? Does it have to do with the way memory works in computers? I know that some memories are way faster than others, but I don't know if that's the real reason for this counter-intuitive performance (when compared to theoretical estimates).

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  • Use a SQL Database for a Desktop Game

    - by sharethis
    Developing a Game Engine I am planning a computer game and its engine. There will be a 3 dimensional world with first person view and it will be single player for now. The programming language is C++ and it uses OpenGL. Data Centered Design Decision My design decision is to use a data centered architecture where there is a global event manager and a global data manager. There are many components like physics, input, sound, renderer, ai, ... Each component can trigger and listen to events. Moreover, each component can read, edit, create and remove data. The question is about the data manager. Whether to Use a Relational Database Should I use a SQL Database, e.g. SQLite or MySQL, to store the game data? This contains virtually all game content like items, characters, inventories, ... Except of meshes and textures which are even more performance related, so I will keep them in memory. Is a SQL database fast enough to use it for realtime reading and writing game informations, like the position of a moving character? I also need to care about cross-platform compatibility. Aside from keeping everything in memory, what alternatives do I have? Advantages Would Be The advantages of using a relational database like MySQL would be the data orientated structure which allows fast computation. I would not need objects for representing entities. I could easily query data of objects near the player needed for rendering. And I don't have to take care about data of objects far away. Moreover there would be no need for savegames since the hole game state is saved in the database. Last but not least, expanding the game to an online game would be relative easy because there already is a place where the hole game state is stored.

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  • Java single Array best choice for accessing pixels for manipulation?

    - by Petrol
    I am just watching this tutorial https://www.youtube.com/watch?v=HwUnMy_pR6A and the guy (who seems to be pretty competent) is using a single array to store and access the pixels of his to-be-rendered image. I was wondering if this really is the best way to do this. The alternative of Multi-Array does have one pointer more, but Arrays do have an O(1) for accessing each index and calculating the index in a single array seems to take one addition and one multiplication operation per pixel. And if Multi-Arrays really are bad, can't you use something with Hashing to avoid those addition and multiplication operations? EDIT: here is his code... public class Screen { private int width, height; public int[] pixels; public Screen(int width, int height) { this.width = width; this.height = height; // creating array the size of one index/int for every pixel // single array has better performance than multi-array pixels = new int[width * height]; } public void render() { for (int y = 0; y < height; y++) { for (int x = 0; x < width; x++) { pixels[x + y * width] = 0xff00ff; } } } }

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  • Challenge 19 – An Explanation of a Query

    - by Dave Ballantyne
    I have received a number of requests for an explanation of my winning query of TSQL Challenge 19. This involved traversing a hierarchy of employees and rolling a count of orders from subordinates up to superiors. The first concept I shall address is the hierarchyId , which is constructed within the CTE called cteTree.   cteTree is a recursive cte that will expand the parent-child hierarchy of the personnel in the table @emp.  One useful feature with a recursive cte is that data can be ‘passed’ from the parent to the child data.  The hierarchyId column is similar to the hierarchyId data type that was introduced in SQL Server 2008 and represents the position of the person within the organisation. Let us start with a simplistic example Albert manages Bob and Eddie.  Bob manages Carl and Dave. The hierarchyId will represent each person’s position in this relationship in a single field.  In this simple example we could append the userID together into a varchar field as detailed below. This will enable us to select a branch of the tree by filtering using Where hierarchyId  ‘1,2%’ to select Bob and all his subordinates.  Naturally, this is not comprehensive enough to provide a full solution, but as opposed to concatenating the Id’s together into a varchar datatyped column, we can apply the same theory to a varbinary.  By CASTing the ID’s into a datatype of varbinary(4) ,4 is used as 4 bytes of data are used to store an integer and building a hierarchyId  from those.  For example: The important point to bear in mind for later in the query is that the binary data generated is 'byte order comparable'. ie We can ORDER a dataset with it and the resulting data, will be in the order required. Now, would probably be a good time to download the example file and, after the cte ‘cteTree’, uncomment the line ‘select * from cteTree’.  Mark this and all prior code and execute.  This will show you how this theory directly relates to the actual challenge data.  The only deviation from the above, is that instead of using the ID of an employee, I have used the row_number() ranking function to order each level by LastName,Firstname.  This enables me to order by the HierarchyId in the final result set so that the result set is in the required order. Your output should be something like the below.  Notice also the ‘Level’ Column that contains the depth that the employee is within the tree.  I would encourage you to ‘play’ with the query, change the order in the row_number() or the length of the cast in the hierarchyId to see how that effects the outcome.  The next cte, ‘cteTreeWithOrderCount’, is a join between cteTree and the @ord table, and COUNT’s the number of orders per employee.  A LEFT JOIN is employed here to account for the occasion where an employee has made no sales.   Executing a ‘Select * from cteTreeWithOrderCount’ will return the result set as below.  The order here is unimportant as this is only a staging point of the data and only the final result set in a cte chain needs an Order by clause, unless TOP is utilised. cteExplode joins the above result set to the tally table (Nums) for Level Occurances.  So, if level is 2 then 2 rows are required.  This is done to expand the dataset, to create a new column (PathInc), which is the (n+1) integers contained within the heirarchyid.  For example, with the data for Robert King as given above, the below 3 rows will be returned. From this you can see that the pathinc column now contains the values for Andrew Fuller and Steven Buchanan who are Robert King’s superiors within the tree.    Finally cteSumUp, sums the orders for each person and their subordinates using the PathInc generated above, and the final select does the final simple mathematics and filters to restrict the result set to only the ‘original’ row per employee.

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  • What is the Relative Performance of Pseudo-Class and Custom Selectors?

    - by James Wiseman
    It's my understanding that, in terms of selector speed, that #ID selectors are fastest, followed by element selectors, and then .class selectors. I have always assumed that pseudo-class selectors and custom selectors (those in the form ':selector') are similar to .class selectors, but I realised that I'm just not sure. I realise that this does depend on the complexity of the code within the pseudo-class/custom selector, so I guess I'd like to know the answer with this excluded as factor. Any help would be appreciated. Thanks.

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  • How To Publish Business Objects Query Service

    - by ssorrrell
    We are trying to copy a BO Query Service from one Universe to another. If you use the BO Query As A Service(QAAS) tool you can do this, but end up basically recreating the query service. It seems like the BusinessObjects.DSWS.* libraries allow you to read and write query services, but those don't appear in the QAAS tool. I think that those queries go into a different Universe than the QAAS tool pings. Perhaps there is a Universe for data and another for Web Service Queries. Monitoring the QAAS tool for HTTP traffic revealed that the BO Web Service used to run queries for the data they contain is also used to manage the Web Service queries. I was able to copy one Query Service into a new one in a new Universe using a Replace() on the XML string in QuerySpec to change the UniverseID. We can basically copy one Query Service to another Universe without manually rebuilding it except for one little thing. The QAAS tool includes a Publish button. This does something unknown, but important. Perhaps it makes some SOAP, WSDL or config files so that the copied Query Service is public. There doesn't seem to be any HTTP traffic to snoop on when it's doing this. The BusinessObjects.DSWS.* libraries include a Publish feature, but it's not for Query Services. It's for general files like Excel and PDF. Right now, we are relegated to using two tools. Does anyone know about how to Publish a BO Query Service programmatically just like the QAAS Tool?

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  • Ever any performance different between Java >> and >>> right shift operators?

    - by Sean Owen
    Is there ever reason to think the (signed) and (unsigned) right bit-shift operators in Java would perform differently? I can't detect any difference on my machine. This is purely an academic question; it's never going to be the bottleneck I'm sure. I know: it's best to write what you mean foremost; use for division by 2, for example. I assume it comes down to which architectures have which operations implemented as an instruction.

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  • Will client side performance improve if images/scripts/styles on different subdomains?

    - by Andrey
    Hi, I have a domain specifically for static content, so cookies don't travel along with requests to images/scripts/css. Now, I think I've read somewhere that most browsers only open one download thread for each domain/subdomain, so different static content can't be downloaded in parallel if on the same domain. Will it make difference for browsers if i place scripts in script.mycdn.com, styles in css.mycdn.com and images in images.mycdn.com? Will it allow to let browser download images at the same time as scripts and styles? mycdn.com is of course a made up name :) Thanks! Andrey

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  • Query to find the data for every month of last year from the given date using mysql?

    - by Salil
    Hi All, I want data for the the last 1 year from the given date For ex:- I have date "2013-06-01" and i want data as follows also data i want is from three table using Group By or something else Month             Amount         Total_Data June 2013     100                5 May 2013       80                  4 -                     100                5 -                     100                5 July 2012       10                  2 I try following query but didn't workout SELECT DATE_FORMAT(rf.period, '%M %Y') as Month , sum(p.amount * ((100-q.amount)/100)) as Amount ,count(distinct q.label_id) as Total Data FROM table1 rf , table2 p , table3 q ,table4 a where rf.period BETWEEN '2013-06-01' AND '2013-06-01' and q.royalty_period BETWEEN '2013-06-01' AND '2013-06-01' and a.id = q.album_id and p.file_id = rf.id and p.upc = a.upc and p.local_revenue is not null GROUP BY Month Thanks in Advance, Salil Gaikwad

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  • Appengine datastore phantom entity - inconsistent state?

    - by aloo
    Getting a weird error on java appengine code that used to work fine (nothing has changed but the data in the datastore). I'm trying to iterate over the results of a query and change a few properties of the entities. The query does return a set of results, however, when I try to access the first result in the list, it throws an exception when trying to access any of its properties (but its key). Here's the exception: org.datanucleus.state.JDOStateManagerImpl isLoaded: Exception thrown by StateManager.isLoaded Could not retrieve entity of kind OnTheCan with key OnTheCan(3204258) org.datanucleus.exceptions.NucleusObjectNotFoundException: Could not retrieve entity of kind OnTheCan with key OnTheCan(3204258) at org.datanucleus.store.appengine.DatastoreExceptionTranslator.wrapEntityNotFoundException(DatastoreExceptionTranslator.java:60) And here is my code: PersistenceManager pm = PMF.get().getPersistenceManager(); Query query = null; List<OnTheCan> cans; query = pm.newQuery("SELECT this FROM " + OnTheCan.class.getName() + " WHERE open == true ORDER BY onTheCanId ASC"); query.setRange(0, num); cans = (List<OnTheCan>) query.execute(); for (OnTheCan c : cans) { System.err.println(c.getOnTheCanId()); // this works fine! getting the key works c.setOpen(false); // failure here with the above exception c.setAutoClosed(true); c.setEndTime(new Date(c.getStartTime().getTime() + 600000/*10*60*1000*/)); } pm.close(); The code throws the exception when trying to execute c.setOpen(false) - thats the first time I'm accessing or setting a property that isnt the key. So it seems there is a phantom entity in my datastore with key 3204258. THis entity doesn't really exist (queried the datastore from admin console) but for some reason its being returned by the query. Could my data store be in an inconsistent state? I've managed the following workaround by placing it as the first line in my for loop. Clearly an ugly hack: if (c.getOnTheCanId() == 3204258) { continue; } Any ideas?

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  • How can I get a distinct list of elements in a hierarchical query?

    - by RenderIn
    I have a database table, with people identified by a name, a job and a city. I have a second table that contains a hierarchical representation of every job in the company in every city. Suppose I have 3 people in the people table: [name(PK),title,city] Jim, Salesman, Houston Jane, Associate Marketer, Chicago Bill, Cashier, New York And I have thousands of job type/location combinations in the job table, a sample of which follow. You can see the hierarchical relationship since parent_title is a foreign key to title: [title,city,pay,parent_title] Salesman, Houston, $50000, CEO Cashier, Houston, $25000 CEO, USA, $1000000 Associate Marketer, Chicago, $75000 Senior Marketer, Chicago, $125000 ..... The problem I'm having is that my Person table is a composite key, so I don't know how to structure the start with part of my query so that it starts with each of the three jobs in the cities I specified. I can execute three separate queries to get what I want, but this doesn't scale well. e.g.: select * from jobs start with city = (select city from people where name = 'Bill') and title = (select title from people where name = 'Bill') connect by prior parent_title = title UNION select * from jobs start with city = (select city from people where name = 'Jim') and title = (select title from people where name = 'Jim') connect by prior parent_title = title UNION select * from jobs start with city = (select city from people where name = 'Jane') and title = (select title from people where name = 'Jane') connect by prior parent_title = title How else can I get a distinct list (or I could wrap it with a distinct if not possible) of all the jobs which are above the three people I specified?

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  • Bulk retrieval in HQL: could not execute native bulk manipulation query

    - by user179056
    Hello, We are getting a "could not execute native bulk manipulation query" error in HQL When we execute a query which is something like this. String query = "Select person.id from Person person where"; String bindParam = ""; List subLists = getChucnkedList(dd); for(int i = 0 ; i < subLists.size() ;i++){ bindParam = bindParam + " person.id in (:param" + i + ")"; if (i < subLists.size() - 1 ) { bindParam = bindParam + " OR " ; } } query = query + bindParam; final Query query1 = session.createQuery(query.toString()); for(int i = 0 ; i < subLists.size() ;i++){ query1.setParameterList("param" + i, subLists.get(i)); } List personIdsList = query1.list(); Basically to avoid the limit on IN clause in terms of number of ids which can be inserted (not more than 1000), we have created sublists of ids of not more than 1000 in number. We are using bind parameters to bind each sublist. However we still get error "could not execute native bulk manipulation query" How does one avoid the problem of limited parameters possible in IN query when parameters passed are more than 1000? regards Sameer

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  • How best to pre-install OR pre-load OR cache Java Script library to optimize performance.

    - by Kabeer
    Hello. I am working for an intranet application. Therefore I have some control on the client machines. The Java Script library I am using is somewhat big in size. I would like to pre-install OR pre-load OR cache the Java Script library on each machine (each browser as well) so that it does not travel for each request. I know that browsers do cache a Java Script library for subsequent requests but I would like the library to be cached once so all subsequent requests, sessions and users. What is the best mechanism to achieve this?

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