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• Columnstore Case Study #1: MSIT SONAR Aggregations

  - by aspiringgeek

  Preamble This is the first in a series of posts documenting big wins encountered using columnstore indexes in SQL Server 2012 & 2014.  Many of these can be found in this deck along with details such as internals, best practices, caveats, etc.  The purpose of sharing the case studies in this context is to provide an easy-to-consume quick-reference alternative. Why Columnstore? If we’re looking for a subset of columns from one or a few rows, given the right indexes, SQL Server can do a superlative job of providing an answer. If we’re asking a question which by design needs to hit lots of rows—DW, reporting, aggregations, grouping, scans, etc., SQL Server has never had a good mechanism—until columnstore. Columnstore indexes were introduced in SQL Server 2012. However, they're still largely unknown. Some adoption blockers existed; yet columnstore was nonetheless a game changer for many apps.  In SQL Server 2014, potential blockers have been largely removed & they're going to profoundly change the way we interact with our data.  The purpose of this series is to share the performance benefits of columnstore & documenting columnstore is a compelling reason to upgrade to SQL Server 2014. App: MSIT SONAR Aggregations At MSIT, performance & configuration data is captured by SCOM. We archive much of the data in a partitioned data warehouse table in SQL Server 2012 for reporting via an application called SONAR.  By definition, this is a primary use case for columnstore—report queries requiring aggregation over large numbers of rows.  New data is refreshed each night by an automated table partitioning mechanism—a best practices scenario for columnstore. The Win Compared to performance using classic indexing which resulted in the expected query plan selection including partition elimination vs. SQL Server 2012 nonclustered columnstore, query performance increased significantly.  Logical reads were reduced by over a factor of 50; both CPU & duration improved by factors of 20 or more.  Other than creating the columnstore index, no special modifications or tweaks to the app or databases schema were necessary to achieve the performance improvements.  Existing nonclustered indexes were rendered superfluous & were deleted, thus mitigating maintenance challenges such as defragging as well as conserving disk capacity. Details The table provides the raw data & summarizes the performance deltas. Logical Reads (8K pages) CPU (ms) Durn (ms) Columnstore 160,323 20,360 9,786 Conventional Table & Indexes 9,053,423 549,608 193,903 ? x56 x27 x20 The charts provide additional perspective of this data.  "Conventional vs. Columnstore Metrics" document the raw data.  Note on this linear display the magnitude of the conventional index performance vs. columnstore.  The “Metrics (?)” chart expresses these values as a ratio. Summary For DW, reports, & other BI workloads, columnstore often provides significant performance enhancements relative to conventional indexing.  I have documented here, the first in a series of reports on columnstore implementations, results from an initial implementation at MSIT in which logical reads were reduced by over a factor of 50; both CPU & duration improved by factors of 20 or more.  Subsequent features in this series document performance enhancements that are even more significant. 

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• Columnstore Case Study #1: MSIT SONAR Aggregations

  - by aspiringgeek

  Preamble This is the first in a series of posts documenting big wins encountered using columnstore indexes in SQL Server 2012 & 2014.  Many of these can be found in this deck along with details such as internals, best practices, caveats, etc.  The purpose of sharing the case studies in this context is to provide an easy-to-consume quick-reference alternative. Why Columnstore? If we’re looking for a subset of columns from one or a few rows, given the right indexes, SQL Server can do a superlative job of providing an answer. If we’re asking a question which by design needs to hit lots of rows—DW, reporting, aggregations, grouping, scans, etc., SQL Server has never had a good mechanism—until columnstore. Columnstore indexes were introduced in SQL Server 2012. However, they're still largely unknown. Some adoption blockers existed; yet columnstore was nonetheless a game changer for many apps.  In SQL Server 2014, potential blockers have been largely removed & they're going to profoundly change the way we interact with our data.  The purpose of this series is to share the performance benefits of columnstore & documenting columnstore is a compelling reason to upgrade to SQL Server 2014. App: MSIT SONAR Aggregations At MSIT, performance & configuration data is captured by SCOM. We archive much of the data in a partitioned data warehouse table in SQL Server 2012 for reporting via an application called SONAR.  By definition, this is a primary use case for columnstore—report queries requiring aggregation over large numbers of rows.  New data is refreshed each night by an automated table partitioning mechanism—a best practices scenario for columnstore. The Win Compared to performance using classic indexing which resulted in the expected query plan selection including partition elimination vs. SQL Server 2012 nonclustered columnstore, query performance increased significantly.  Logical reads were reduced by over a factor of 50; both CPU & duration improved by factors of 20 or more.  Other than creating the columnstore index, no special modifications or tweaks to the app or databases schema were necessary to achieve the performance improvements.  Existing nonclustered indexes were rendered superfluous & were deleted, thus mitigating maintenance challenges such as defragging as well as conserving disk capacity. Details The table provides the raw data & summarizes the performance deltas. Logical Reads (8K pages) CPU (ms) Durn (ms) Columnstore 160,323 20,360 9,786 Conventional Table & Indexes 9,053,423 549,608 193,903 ? x56 x27 x20 The charts provide additional perspective of this data.  "Conventional vs. Columnstore Metrics" document the raw data.  Note on this linear display the magnitude of the conventional index performance vs. columnstore.  The “Metrics (?)” chart expresses these values as a ratio. Summary For DW, reports, & other BI workloads, columnstore often provides significant performance enhancements relative to conventional indexing.  I have documented here, the first in a series of reports on columnstore implementations, results from an initial implementation at MSIT in which logical reads were reduced by over a factor of 50; both CPU & duration improved by factors of 20 or more.  Subsequent features in this series document performance enhancements that are even more significant. 

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• [Smalltalk] Store List of Instruction

  - by Luciano Lorenti

  Hi all, I have a design Problem. i have a Drawer class wich invokes a serie of methods of a kind-of-brush class and i have a predefined shapes which i want to draw. Each shape uses a list of instance methods from the drawer. I can have more than 1 brush object. I want to add custom shapes on runtime in the drawer instance, especifying the list of methods of the new shape. i've created a class method for every predefined shape that returns a BlockClosure with the instruccions. Obviously i have to give to each BlockClosure the brush object as parameter. I imagine a collection with all the BlockClosures in each instance of the Drawer Class. Maybe i can inherit a SequenceableCollection and make a instruccion collection. Each element of the collection it's a instruction and i give the brush object when i instance this new collection. I really don't know the best way to store these steps. (Maybe a shared variable?)

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• Is it poor design to create objects that only execute code during the constructor?

  - by Curtix

  In my design I am using objects that evaluate a data record. The constructor is called with the data record and type of evaluation as parameters and then the constructor calls all of the object's code necessary to evaluate the record. This includes using the type of evaluation to find additional parameter-like data in a text file. There are in the neighborhood of 250 unique evaluation types that use the same or similar code and unique parameters coming from the text file. Some of these evaluations use different code so I benefit a lot from this model because I can use inheritance and polymorphism. Once the object is created there isn't any need to execute additional code on the object (at least for now) and it is used more like a struct; its kept on a list and 3 properties are used later. I think this design is the easiest to understand, code, and read. A logical alternative I guess would be using functions that return score structs, but you can't inherit from methods so it would make it kind of sloppy imo. I am using vb.net and these classes will be used in an asp.net web app as well as in a distributed app. thanks for your input

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• PHP access data of an object

  - by sea_1987

  I have an object of which I am looking to get a piece of data from, the object looks like this, Product Object ( [name] => Simon Test Cup [code] => 123456789 [category_id] => 3 [range_id] => 26 [price] => 10.00 [price_logo_add] => 0.25 [image_id] => 846 [rank] => [special_offer] => N [cartProps] => Array ( ) [section] => [vatPercentage] => 17.5 [id] => 551 [date_created] => 2010-05-25 12:46:57 [last_updated] => 2010-05-25 14:10:48 [user_id_updated] => 0 [_aliases] => Array ( [id] => 551 [date_created] => 2010-05-25 12:46:57 [date_updated] => 2010-05-25 14:10:48 [user_id_updated] => 0 [name] => Simon Test Cup [code] => 123456789 [category_id] => 3 [range_id] => 26 [price] => 10.00 [price_logo_add] => 0.25 [image_id] => 846 [range_image_id] => 848 [main_image_id] => 847 [rank] => [special_offer] => N ) [_default] => Array ( [special_offer] => N ) [_related] => Array ( [_related] => Array ( [range] => stdClass Object ( [key] => range [group] => _related [foreignKey] => range_id [indexName] => id [tableName] => cc_range [objectName] => Range [userFieldlyColName] => name [criteria] => id='{%range_id%}' [sqlPostfix] => [populateOnLoad] => [objects] => Array ( [26] => Range Object ( [name] => Shot glasses [url_name] => shot-glasses [description] => Personalized shot glasses make great commemorative gifts, souvenirs and wedding favours. Just select your favourite shape and send us a customization form with your logo. See our glassware sale page for info on free logo origination. [leader] => Customized shot glasses make great commemorative gifts, promotional items and wedding favours. Individual gift boxes are available so you can give the glasses away easily. [category_id] => 3 [site_id_csv] => [image_id_main] => 565 [image_id_thumb] => 566 [rank] => [site] => main [id] => 26 [date_created] => 2008-05-18 21:39:52 [last_updated] => 2009-02-03 13:49:10 [user_id_updated] => 0 [_aliases] => Array I am wanting to get the id from the [range] = stdClass Object

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• MySQL Cluster 7.2: Over 8x Higher Performance than Cluster 7.1

  - by Mat Keep

  0 0 1 893 5092 Homework 42 11 5974 14.0 Normal 0 false false false EN-US JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:Cambria; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin; mso-ansi-language:EN-US;} Summary The scalability enhancements delivered by extensions to multi-threaded data nodes enables MySQL Cluster 7.2 to deliver over 8x higher performance than the previous MySQL Cluster 7.1 release on a recent benchmark What’s New in MySQL Cluster 7.2 MySQL Cluster 7.2 was released as GA (Generally Available) in February 2012, delivering many enhancements to performance on complex queries, new NoSQL Key / Value API, cross-data center replication and ease-of-use. These enhancements are summarized in the Figure below, and detailed in the MySQL Cluster New Features whitepaper Figure 1: Next Generation Web Services, Cross Data Center Replication and Ease-of-Use Once of the key enhancements delivered in MySQL Cluster 7.2 is extensions made to the multi-threading processes of the data nodes. Multi-Threaded Data Node Extensions The MySQL Cluster 7.2 data node is now functionally divided into seven thread types: 1) Local Data Manager threads (ldm). Note – these are sometimes also called LQH threads. 2) Transaction Coordinator threads (tc) 3) Asynchronous Replication threads (rep) 4) Schema Management threads (main) 5) Network receiver threads (recv) 6) Network send threads (send) 7) IO threads Each of these thread types are discussed in more detail below. MySQL Cluster 7.2 increases the maximum number of LDM threads from 4 to 16. The LDM contains the actual data, which means that when using 16 threads the data is more heavily partitioned (this is automatic in MySQL Cluster). Each LDM thread maintains its own set of data partitions, index partitions and REDO log. The number of LDM partitions per data node is not dynamically configurable, but it is possible, however, to map more than one partition onto each LDM thread, providing flexibility in modifying the number of LDM threads. The TC domain stores the state of in-flight transactions. This means that every new transaction can easily be assigned to a new TC thread. Testing has shown that in most cases 1 TC thread per 2 LDM threads is sufficient, and in many cases even 1 TC thread per 4 LDM threads is also acceptable. Testing also demonstrated that in some instances where the workload needed to sustain very high update loads it is necessary to configure 3 to 4 TC threads per 4 LDM threads. In the previous MySQL Cluster 7.1 release, only one TC thread was available. This limit has been increased to 16 TC threads in MySQL Cluster 7.2. The TC domain also manages the Adaptive Query Localization functionality introduced in MySQL Cluster 7.2 that significantly enhanced complex query performance by pushing JOIN operations down to the data nodes. Asynchronous Replication was separated into its own thread with the release of MySQL Cluster 7.1, and has not been modified in the latest 7.2 release. To scale the number of TC threads, it was necessary to separate the Schema Management domain from the TC domain. The schema management thread has little load, so is implemented with a single thread. The Network receiver domain was bound to 1 thread in MySQL Cluster 7.1. With the increase of threads in MySQL Cluster 7.2 it is also necessary to increase the number of recv threads to 8. This enables each receive thread to service one or more sockets used to communicate with other nodes the Cluster. The Network send thread is a new thread type introduced in MySQL Cluster 7.2. Previously other threads handled the sending operations themselves, which can provide for lower latency. To achieve highest throughput however, it has been necessary to create dedicated send threads, of which 8 can be configured. It is still possible to configure MySQL Cluster 7.2 to a legacy mode that does not use any of the send threads – useful for those workloads that are most sensitive to latency. The IO Thread is the final thread type and there have been no changes to this domain in MySQL Cluster 7.2. Multiple IO threads were already available, which could be configured to either one thread per open file, or to a fixed number of IO threads that handle the IO traffic. Except when using compression on disk, the IO threads typically have a very light load. Benchmarking the Scalability Enhancements The scalability enhancements discussed above have made it possible to scale CPU usage of each data node to more than 5x of that possible in MySQL Cluster 7.1. In addition, a number of bottlenecks have been removed, making it possible to scale data node performance by even more than 5x. Figure 2: MySQL Cluster 7.2 Delivers 8.4x Higher Performance than 7.1 The flexAsynch benchmark was used to compare MySQL Cluster 7.2 performance to 7.1 across an 8-node Intel Xeon x5670-based cluster of dual socket commodity servers (6 cores each). As the results demonstrate, MySQL Cluster 7.2 delivers over 8x higher performance per data nodes than MySQL Cluster 7.1. More details of this and other benchmarks will be published in a new whitepaper – coming soon, so stay tuned! In a following blog post, I’ll provide recommendations on optimum thread configurations for different types of server processor. You can also learn more from the Best Practices Guide to Optimizing Performance of MySQL Cluster Conclusion MySQL Cluster has achieved a range of impressive benchmark results, and set in context with the previous 7.1 release, is able to deliver over 8x higher performance per node. As a result, the multi-threaded data node extensions not only serve to increase performance of MySQL Cluster, they also enable users to achieve significantly improved levels of utilization from current and future generations of massively multi-core, multi-thread processor designs.

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• License name in startup in Visual studio 2010

  - by anirudha

  Whenever we install Visual studio in our system. we found that Express edition and visual studio never show our name in startup by default they show Microsoft. here is a way to change them with your name or organization name if you want. HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows NT\CurrentVersion go their and check the value for RegisteredOrganization for changing orgranization name in bottom of username or change the RegisteredOwner for changing the name of user.

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• SQL MDS - Updating the Name attribute of member using Staging Table

  - by Randy Aldrich Paulo

  Creating member is usually done by populating the Member Staging Table (tblStgMember), during this process you assign a value for member code and member name. Now if you want to update the member name attribute you can do this by adding record in Attribute staging table (tblStgMemberAttribute) with Attribute Name = "Name". If you try populating the tblStgMember table it will say that the member code already exists.   INSERT INTO mdm.tblStgMemberAttribute (ModelName, EntityName, MemberType_ID, MemberCode, AttributeName, AttributeValue) VALUES (N'Product', N'Product', 1, N'BK-M101', N'Name',N'Updated Member Name Description')

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• Can I register a domain name that contains a company name or trademark? [duplicate]

  - by Orçun yumarci

  This question already has an answer here: Registering a domain name with a trademark in it 2 answers I wonder is it legal to register a domain name that contains a company name. For example cococola.cc (considering that this domain name is available). Can I buy and use any domain names that contain a name of a trademark?

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• How to improve WinForms MSChart performance?

  - by Marcel

  Hi all, I have created some simple charts (of type FastLine) with MSChart and update them with live data, like below: . To do so, I bind an observable collection of a custom type to the chart like so: // set chart data source this._Chart.DataSource = value; //is of type ObservableCollection<SpectrumLevels> //define x and y value members for each series this._Chart.Series[0].XValueMember = "Index"; this._Chart.Series[1].XValueMember = "Index"; this._Chart.Series[0].YValueMembers = "Channel0Level"; this._Chart.Series[1].YValueMembers = "Channel1Level"; // bind data to chart this._Chart.DataBind(); //lasts 1.5 seconds for 8000 points per series At each refresh, the dataset completely changes, it is not a scrolling update! With a profiler I have found that the DataBind() call takes about 1.5 seconds. The other calls are negligible. How can I make this faster? Should I use another type than ObservableCollection? An array probably? Should I use another form of data binding? Is there some tweak for the MSChart that I may have missed? Should I use a sparsed set of date, having one value per pixel only? Have I simply reached the performance limit of MSCharts? From the type of the application to keep it "fluent", we should have multiple refreshes per second. Thanks for any hints!

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• Books and resources for Java Performance tuning - when working with databases, huge lists

  - by Arvind

  Hi All, I am relatively new to working on huge applications in Java. I am working on a Java web service which is pretty heavily used by various clients. The service basically queries the database (hibernate) and then works with a lot of Lists (there are adapters to convert list returned from DB to the interface which the service publishes) and I am seeing lot of issues with the service like high CPU usage or high heap space. While I can troubleshoot the performance issues using a profiler, I want to actually learn about what all I need to take care when I actually write code. Like what kind of List to use or things like using StringBuilder instead of String, etc... Is there any book or blogs which I can refer which will help me while I write new services? Also my application is multithreaded - each service call from a client is a new thread, and I want to know some best practices around that area as well. I did search the web but I found many tips which are not relevant in the latest Java 6 releases, so wanted to know what kind of resources would help a developer starting out now on Java for heavily used applications. Arvind

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• GAE python database object design for simple list of values

  - by Joey

  I'm really new to database object design so please forgive any weirdness in my question. Basically, I am use Google AppEngine (Python) and contructing an object to track user info. One of these pieces of data is 40 Achievement scores. Do I make a list of ints in the User object for this? Or do I make a separate entity with my user id, the achievement index (0-39) and the score and then do a query to grab these 40 items every time I want to get the user data in total? The latter approach seems more object oriented to me, and certainly better if I extend it to have more than just scores for these 40 achievements. However, considering that I might not extend it, should I even consider just doing a simple list of 40 ints in my user data? I would then forgo doing a query, getting the sorted list of achievements, reading the score from each one just to process a response etc. Is doing this latter approach just such a common practice and hand-waved as not even worth batting an eyelash at in terms of thinking it might be more costly or complex processing wise?

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• Error While Linking Multiple C Object files in Delphi 2007

  - by Ramnish

  Hello Everyone. I am new to delphi. I was trying to add C Object files in my Delphi project and link them directly since Delphi Supports C Object Linking. I got it working when i link a single Object file. But when i try to link multiple object files, i am getting error 'Unsatisfied forward or external declaration'. I have tried this in Delphi 2007 as well as XE.So what am i doing wrong here? Working Code: function a_function():Integer;cdecl; implementation {$Link 'a.obj'} function a_function():Integer;cdecl;external; end. Error Code: function a_function():Integer;cdecl; function b_function();Integer;cdecl; function c_function();Integer;cdecl; implementation {$LINK 'a.obj'} {$LINK 'b.obj'} {$LINK 'c.obj'} function a_function():Integer;cdecl;external; function b_function();Integer;cdecl;external; function c_function();Integer;cdecl;external; end.

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• Increase performance on iphone at pdf rendering

  - by burki

  Hi! I have a UITableView, and in every cell there's displayed a UIImage created from a pdf. But now the performance is very bad. Here's my code I use to generate the UIImage from the PDF. Creating CGPDFDocumentRef and UIImageView (in cellForRowAtIndexPath method): ... CFURLRef pdfURL = CFBundleCopyResourceURL(CFBundleGetMainBundle(), (CFStringRef)formula.icon, NULL, NULL); CGPDFDocumentRef documentRef = CGPDFDocumentCreateWithURL((CFURLRef)pdfURL); CFRelease(pdfURL); UIImageView *imageView = [[UIImageView alloc] initWithImage:[self imageFromPDFWithDocumentRef:documentRef]]; ... Generate UIImage: - (UIImage *)imageFromPDFWithDocumentRef:(CGPDFDocumentRef)documentRef { CGPDFPageRef pageRef = CGPDFDocumentGetPage(documentRef, 1); CGRect pageRect = CGPDFPageGetBoxRect(pageRef, kCGPDFCropBox); UIGraphicsBeginImageContext(pageRect.size); CGContextRef context = UIGraphicsGetCurrentContext(); CGContextTranslateCTM(context, CGRectGetMinX(pageRect),CGRectGetMaxY(pageRect)); CGContextScaleCTM(context, 1, -1); CGContextTranslateCTM(context, -(pageRect.origin.x), -(pageRect.origin.y)); CGContextDrawPDFPage(context, pageRef); UIImage *finalImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return finalImage; } What can I do to increas the speed and keep the memory low?

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• Iterator performance contract (and use on non-collections)

  - by polygenelubricants

  If all that you're doing is a simple one-pass iteration (i.e. only hasNext() and next(), no remove()), are you guaranteed linear time performance and/or amortized constant cost per operation? Is this specified in the Iterator contract anywhere? Are there data structures/Java Collection which cannot be iterated in linear time? java.util.Scanner implements Iterator<String>. A Scanner is hardly a data structure (e.g. remove() makes absolutely no sense). Is this considered a design blunder? Is something like PrimeGenerator implements Iterator<Integer> considered bad design, or is this exactly what Iterator is for? (hasNext() always returns true, next() computes the next number on demand, remove() makes no sense). Similarly, would it have made sense for java.util.Random implements Iterator<Double>? Should a type really implement Iterator if it's effectively only using one-third of its API? (i.e. no remove(), always hasNext())

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• Varying performance of MSVC release exe

  - by Andrew

  Hello everyone, I am curious what could be the reason for highly varying performance of the same executable. Sometimes, I run it and it takes 20 seconds and sometimes it is 110. Source is compiled with MSVC in Release mode with standard options. The code is here: vector<double> Un; vector<double> Ucur; double *pUn, *pUcur; ... // time marching for (old_time=time-logfreq, time+=dt; time <= end_time; time+=dt) { for (i=1, j=Un.size()-1, pUn=&Un[1], pUcur=&Ucur[1]; i < j; ++i, ++pUn, ++pUcur) { *pUcur = (*pUn)*(1.0-0.5*alpha*( *(pUn+1) - *(pUn-1) )); } Ucur[0] = (Un[0])*(1.0-0.5*alpha*( Un[1] - Un[j] )); Ucur[j] = (Un[j])*(1.0-0.5*alpha*( Un[0] - Un[j-1] )); Un = Ucur; }

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• Python performance improvement request for winkler

  - by Martlark

  I'm a python n00b and I'd like some suggestions on how to improve the algorithm to improve the performance of this method to compute the Jaro-Winkler distance of two names. def winklerCompareP(str1, str2): """Return approximate string comparator measure (between 0.0 and 1.0) USAGE: score = winkler(str1, str2) ARGUMENTS: str1 The first string str2 The second string DESCRIPTION: As described in 'An Application of the Fellegi-Sunter Model of Record Linkage to the 1990 U.S. Decennial Census' by William E. Winkler and Yves Thibaudeau. Based on the 'jaro' string comparator, but modifies it according to whether the first few characters are the same or not. """ # Quick check if the strings are the same - - - - - - - - - - - - - - - - - - # jaro_winkler_marker_char = chr(1) if (str1 == str2): return 1.0 len1 = len(str1) len2 = len(str2) halflen = max(len1,len2) / 2 - 1 ass1 = '' # Characters assigned in str1 ass2 = '' # Characters assigned in str2 #ass1 = '' #ass2 = '' workstr1 = str1 workstr2 = str2 common1 = 0 # Number of common characters common2 = 0 #print "'len1', str1[i], start, end, index, ass1, workstr2, common1" # Analyse the first string - - - - - - - - - - - - - - - - - - - - - - - - - # for i in range(len1): start = max(0,i-halflen) end = min(i+halflen+1,len2) index = workstr2.find(str1[i],start,end) #print 'len1', str1[i], start, end, index, ass1, workstr2, common1 if (index > -1): # Found common character common1 += 1 #ass1 += str1[i] ass1 = ass1 + str1[i] workstr2 = workstr2[:index]+jaro_winkler_marker_char+workstr2[index+1:] #print "str1 analyse result", ass1, common1 #print "str1 analyse result", ass1, common1 # Analyse the second string - - - - - - - - - - - - - - - - - - - - - - - - - # for i in range(len2): start = max(0,i-halflen) end = min(i+halflen+1,len1) index = workstr1.find(str2[i],start,end) #print 'len2', str2[i], start, end, index, ass1, workstr1, common2 if (index > -1): # Found common character common2 += 1 #ass2 += str2[i] ass2 = ass2 + str2[i] workstr1 = workstr1[:index]+jaro_winkler_marker_char+workstr1[index+1:] if (common1 != common2): print('Winkler: Wrong common values for strings "%s" and "%s"' % \ (str1, str2) + ', common1: %i, common2: %i' % (common1, common2) + \ ', common should be the same.') common1 = float(common1+common2) / 2.0 ##### This is just a fix ##### if (common1 == 0): return 0.0 # Compute number of transpositions - - - - - - - - - - - - - - - - - - - - - # transposition = 0 for i in range(len(ass1)): if (ass1[i] != ass2[i]): transposition += 1 transposition = transposition / 2.0 # Now compute how many characters are common at beginning - - - - - - - - - - # minlen = min(len1,len2) for same in range(minlen+1): if (str1[:same] != str2[:same]): break same -= 1 if (same > 4): same = 4 common1 = float(common1) w = 1./3.*(common1 / float(len1) + common1 / float(len2) + (common1-transposition) / common1) wn = w + same*0.1 * (1.0 - w) return wn

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• Haskell math performance

  - by Travis Brown

  I'm in the middle of porting David Blei's original C implementation of Latent Dirichlet Allocation to Haskell, and I'm trying to decide whether to leave some of the low-level stuff in C. The following function is one example—it's an approximation of the second derivative of lgamma: double trigamma(double x) { double p; int i; x=x+6; p=1/(x*x); p=(((((0.075757575757576*p-0.033333333333333)*p+0.0238095238095238) *p-0.033333333333333)*p+0.166666666666667)*p+1)/x+0.5*p; for (i=0; i<6 ;i++) { x=x-1; p=1/(x*x)+p; } return(p); } I've translated this into more or less idiomatic Haskell as follows: trigamma :: Double -> Double trigamma x = snd $ last $ take 7 $ iterate next (x' - 1, p') where x' = x + 6 p = 1 / x' ^ 2 p' = p / 2 + c / x' c = foldr1 (\a b -> (a + b * p)) [1, 1/6, -1/30, 1/42, -1/30, 5/66] next (x, p) = (x - 1, 1 / x ^ 2 + p) The problem is that when I run both through Criterion, my Haskell version is six or seven times slower (I'm compiling with -O2 on GHC 6.12.1). Some similar functions are even worse. I know practically nothing about Haskell performance, and I'm not terribly interested in digging through Core or anything like that, since I can always just call the handful of math-intensive C functions through FFI. But I'm curious about whether there's low-hanging fruit that I'm missing—some kind of extension or library or annotation that I could use to speed up this numeric stuff without making it too ugly.

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• Reading DATA from an OBJECT asp.net MVC C#

  - by kalyan

  Hi, I am new to the MVC and I am stuck with a wierd situation. I have to read the Data from the type object and I tried different ways and I couldn't get a solution.Please help. IList<User> u = new UserRepository().Getuser(Name.ToUpper(), UserName.ToUpper(), UserCertNumber.ToUpper(), Date.ToUpper(), UserType.ToUpper(), Company.ToUpper(), PageNumber, Orderby, SearchALL.ToUpper(), PrintAllPages.ToUpper()); object[] users = new object[u.Count]; for (int i = 0; i < u.Count; i++) { users[i] = new { Id = u[i].UserId, Title = u[i].Title, FirstName = u[i].FirstName, LastName = u[i].LastName, Privileges = (from apps in u[i].UserPrivileges select new { PrivilegeId = apps.Privilege.PrivilegeId, PrivilegeName = apps.Privilege.Name, DeactiveDate = apps.DeactiveDate }), Status = (from status in u[i].UserStatus select new { StatusId = status.Status.StatusId, StatusName = status.Status.StatusName, DeactiveDate = status.DeactiveDate }), ActiveDate = u[i].ActiveDate, UserName = u[i].Email, UserCN = (from cert in u[i].UserCertificates select new { CertificateNumber = cert.CertificateNumber, DeactiveDate = cert.DeactiveDate }), Company = u[i].Company.Name }; } string x = ""; string y = ""; var report = users; foreach (var r in report) { x = r[0].....; i want to assign the values from the report to something else and I am not able to read the data from the report object. Please help. } Thank you.

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• Performance of Java matrix math libraries?

  - by dfrankow

  We are computing something whose runtime is bound by matrix operations. (Some details below if interested.) This experience prompted the following question: Do folk have experience with the performance of Java libraries for matrix math (e.g., multiply, inverse, etc.)? For example: JAMA: http://math.nist.gov/javanumerics/jama/ COLT: http://acs.lbl.gov/~hoschek/colt/ Apache commons math: http://commons.apache.org/math/ I searched and found nothing. Details of our speed comparison: We are using Intel FORTRAN (ifort (IFORT) 10.1 20070913). We have reimplemented it in Java (1.6) using Apache commons math 1.2 matrix ops, and it agrees to all of its digits of accuracy. (We have reasons for wanting it in Java.) (Java doubles, Fortran real*8). Fortran: 6 minutes, Java 33 minutes, same machine. jvisualm profiling shows much time spent in RealMatrixImpl.{getEntry,isValidCoordinate} (which appear to be gone in unreleased Apache commons math 2.0, but 2.0 is no faster). Fortran is using Atlas BLAS routines (dpotrf, etc.). Obviously this could depend on our code in each language, but we believe most of the time is in equivalent matrix operations. In several other computations that do not involve libraries, Java has not been much slower, and sometimes much faster.

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• Cannot convert object, recieved from ajax call, into a long

  - by Matt

  I'm using Asp.Net-Mvc, I have this method in my controller: [AcceptVerbs(HttpVerbs.Post)] public ActionResult LinkAccount(string site, object id) { return this.Json(id); } Here's the ajax method that calls it: $.post("/Account/LinkAccount", { site: "Facebook", id: FB.Facebook.apiClient.get_session().uid }, function(result) { alert(result); }, "json" ); returning this.Json(id); makes the alert work... it alerts 7128383 (something similar to that). but if I change this.Json(id) to this.Json(Conver.ToInt64(id)); the alert does not fire... Any idea of why I can't convert an object received from an object to a long? I already know changing the LinkAccount method to accept a long instead works just fine. It's just I need it as an object because some other sites I'm linking up have strings for id's rather than longs. UPDATE: I tried running the code on localhost so I could set a breakpoint. First I changed the line return this.Json(Convert.ToInt64(id)); to long idAsLong = Convert.ToInt64(id));. Here's what the debugger is telling me: When I hover over id it says: "id | {string[1]}" and when I press the plus button is shows: "[0] | '7128383'" When I hover over idAsLong, it says: "idAsLong | 0" Why isn't it converting it properly?

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• Mysql InnoDB performance optimization and indexing

  - by Davide C

  Hello everybody, I have 2 databases and I need to link information between two big tables (more than 3M entries each, continuously growing). The 1st database has a table 'pages' that stores various information about web pages, and includes the URL of each one. The column 'URL' is a varchar(512) and has no index. The 2nd database has a table 'urlHops' defined as: CREATE TABLE urlHops ( dest varchar(512) NOT NULL, src varchar(512) DEFAULT NULL, timestamp timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP, KEY dest_key (dest), KEY src_key (src) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 Now, I need basically to issue (efficiently) queries like this: select p.id,p.URL from db1.pages p, db2.urlHops u where u.src=p.URL and u.dest=? At first, I thought to add an index on pages(URL). But it's a very long column, and I already issue a lot of INSERTs and UPDATEs on the same table (way more than the number of SELECTs I would do using this index). Other possible solutions I thought are: -adding a column to pages, storing the md5 hash of the URL and indexing it; this way I could do queries using the md5 of the URL, with the advantage of an index on a smaller column. -adding another table that contains only page id and page URL, indexing both columns. But this is maybe a waste of space, having only the advantage of not slowing down the inserts and updates I execute on 'pages'. I don't want to slow down the inserts and updates, but at the same time I would be able to do the queries on the URL efficiently. Any advice? My primary concern is performance; if needed, wasting some disk space is not a problem. Thank you, regards Davide

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• Performance of map overlay in conjunction with ItemizedOverlay is very poor

  - by oviroa

  I am trying to display one png (drawable) on a map in about 300 points. I am retrieving the coordinates from a Sqlite table, dumping them in a cursor. When I try to display them by parsing through the cursor, it takes for ever for the images to be drawn, about .5 second per image. I find that to be suspiciously slow, so some insight on how I can increase performance would help. Here is the snippet of my code that does the rendering: while (!mFlavorsCursor.isAfterLast()) { Log.d("cursor",""+(i++)); point = new GeoPoint( (int)(mFlavorsCursor.getFloat(mFlavorsCursor.getColumnIndex(DataBaseHelper.KEY_LATITUDE))*1000000), (int)(mFlavorsCursor.getFloat(mFlavorsCursor.getColumnIndex(DataBaseHelper.KEY_LONGITUDE))*1000000)); overlayitem = new OverlayItem(point, "", ""); itemizedoverlay.addOverlay(overlayitem); itemizedoverlay.doPopulate(); mFlavorsCursor.moveToNext(); } mapOverlays.add(itemizedoverlay); I tried to isolate all the steps and it looks like the slow one is this: itemizedoverlay.doPopulate(); This is a public method in my class that extends ItemizedOverlay that runs the private populate() method.

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• C# vs C - Big performance difference

  - by John

  I'm finding massive performance differences between similar code in C anc C#. The C code is: #include <stdio.h> #include <time.h> #include <math.h> main() { int i; double root; clock_t start = clock(); for (i = 0 ; i <= 100000000; i++){ root = sqrt(i); } printf("Time elapsed: %f\n", ((double)clock() - start) / CLOCKS_PER_SEC); } And the C# (console app) is: using System; using System.Collections.Generic; using System.Text; namespace ConsoleApplication2 { class Program { static void Main(string[] args) { DateTime startTime = DateTime.Now; double root; for (int i = 0; i <= 100000000; i++) { root = Math.Sqrt(i); } TimeSpan runTime = DateTime.Now - startTime; Console.WriteLine("Time elapsed: " + Convert.ToString(runTime.TotalMilliseconds/1000)); } } } With the above code, the C# completes in 0.328125 seconds (release version) and the C takes 11.14 seconds to run. The c is being compiled to a windows executable using mingw. I've always been under the assumption that C/C++ were faster or at least comparable to C#.net. What exactly is causing the C to run over 30 times slower? EDIT: It does appear that the C# optimizer was removing the root as it wasn't being used. I changed the root assignment to root += and printed out the total at the end. I've also compiled the C using cl.exe with the /O2 flag set for max speed. The results are now: 3.75 seconds for the C 2.61 seconds for the C# The C is still taking longer, but this is acceptable

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• Does SetFileBandwidthReservation affect memory-mapped file performance?

  - by Ghostrider

  Does this function affect Memory-mapped file performance? Here's the problem I need to solve: I have two applications competing for disk access: "reader" and "updater". Whole system runs on Windows Server 2008 R2 x64 "Updater" constantly accesses disk in a linear manner, updating data. They system is set up in such a way that updater always has infinite data to update. Consider that it is constantly approximating a solution of a huge set of equations that takes up entire 2TB disk drive. Updater uses ReadFile and WriteFile to process data in a linear fashion. "Reader" is occasionally invoked by user to get some pieces of data. Usually user would read several 4kb blocks from the drive and stop. Occasionally user needs to read up to 100mb sequentially. In exceptional cases up to several gigabytes. Reader maps files to memory to get data it needs. What I would like to achieve is for "reader" to have absolute priority so that "updater" would completely stop if needed so that "reader" could get the data user needs ASAP. Is this problem solvable by using SetPriorityClass and SetFileBandwidthReservation calls? I would really hate to put synchronization login in "reader" and "updater" and rather have the OS take care of priorities.

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