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  • [Java] Nested methods vs "piped" methods, which is better?

    - by Michael Mao
    Hi: Since uni, I've programming in Java for 3 years, although I am not fully dedicated to this language, I have spent quite some time in it, nevertheless. I understand both ways, just curious which style do you prefer. public class Test{ public static void main(String[] args) { System.out.println(getAgent().getAgentName()); } private static Agent getAgent() { return new Agent(); }} class Agent{ private String getAgentName() { return "John Smith"; }} I am pretty happy with nested method calls such like the following public class Test{ public static void main(String[] args) { getAgentName(getAgent()); } private static void getAgentName(Agent agent) { System.out.println(agent.getName()); } private static Agent getAgent() { return new Agent(); }} class Agent { public String getName(){ return "John Smith"; }} They have identical output I saw "John Smith" twice. I wonder, if one way of doing this has better performance or other advantages over the other. Personally I prefer the latter, since for nested methods I can certainly tell which starts first, and which is after. The above code is but a sample, The code that I am working with now is much more complicated, a bit like a maze... So switching between the two styles often blows my head in no time.

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  • DataReader-DataSet Hybrid solution

    - by G33kKahuna
    My solution architects and I have exhausted both pure Dataset and Datareader solutions. Basically we have a Microsoft.NET 2.0 windows service application that pulls data based on a query and processes additional tasks per record; almost a poor mans workflow system. The recordsets are broader (in terms of the columns) and deeper (in terms of number of records). We observed that DataSet performs much better in terms of performance but runs into contraints as # of records increase say 100K+ we start seeing System.OutOfMemoryException on a 4G machine with processModel configured to run at memoryLimit set to 85. Since this is a multi-threaded app, there could be multiple threads processing different queries and building different DataSets, so we run into the exception sooner in that case DataReader on the other hand works but is a lot slower and hits other contraints; if there is some sort of disconnect it has to start over again or leaves open connections on the DB side and worst case takes down the service completely etc. So, we decided the best option would be some sort of hybrid solution. I'm open to guidance and suggestions. Are there any hybrid solutions available? Any other suggestions

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  • PHP autoloader: ignoring non-existing include

    - by Bart van Heukelom
    I have a problem with my autoloader: public function loadClass($className) { $file = str_replace(array('_', '\\'), '/', $className) . '.php'; include_once $file; } As you can see, it's quite simple. I just deduce the filename of the class and try to include it. I have a problem though; I get an exception when trying to load a non-existing class (because I have an error handler which throws exceptions). This is inconvenient, because it's also fired when you use class_exists() on a non-existing class. You don't want an exception there, just a "false" returned. I fixed this earlier by putting an @ before the include (supressing all errors). The big drawback with this, though, is that any parser/compiler errors (that are fatal) in this include won't show up (not even in the logs), resulting in a hard to find bug. What would be the best way to solve both problems at once? The easiest way would be to include something like this in the autoloader (pseudocode): foreach (path in the include_path) { if (is_readable(the path + the class name)) readable = true; } if (!readable) return; But I worry about the performance there. Would it hurt a lot? (Solved) Made it like this: public function loadClass($className) { $file = str_replace(array('_', '\\'), '/', $className) . '.php'; $paths = explode(PATH_SEPARATOR, get_include_path()); foreach ($paths as $path) { if (is_readable($path . '/' . $file)) { include_once $file; return; } } }

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  • How to lazy load scripts in YUI that accompany ajax html fragments

    - by Chris Beck
    I have a web app with Tabs for Messages and Contacts (think gmail). Each Tab has a Y.on('click') event listener that retrieves an HTML fragment via Y.io() and renders the fragment via node.setContent(). However, the Contact Tab also requires contact.js to enable an Edit button in the fragment. How do I defer the cost of loading contact.js until the user clicks on the Contacts tab? How should contact.js add it's listener to the Edit button? The Complete function of my Tab's on('click') event could serialize Get.script('contact.js') after Y.io('fragment'). However, for better performance, I would prefer to download the script in parallel to downloading the HTML fragment. In that case, I would need to defer adding an event listener to the Edit button until the Edit button is available. This seems like a common RIA design pattern. What is the best way to implement this with YUI? How should I get the script? How should I defer sections of the script until elements in the fragment are available in the DOM?

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  • how do i work bool!

    - by user350217
    HI! im a beginner and im really getting frustrated with this whole concept. i dont understand how to exactly use the bool function. i know what it is but i cantfigure out how to make it work in my program. Im trying to say that if my variable "selection" is any letter beween 'A' and 'I' then it is valid and can continue on to the next function which is called calcExchangeAmt(amtExchanged, selection). if it is false i want it to ask the user if they want to repeat the program and if they agree to repeat i want it to clear the screen and restart to the main function. please help edit my work! this is my bool function: bool isSelectionValid(char selection, char yesNo, double amtExchanged) { bool validData; validData = true; if((selection >= 'a' && selection <= 'i') || (selection >= 'A' && selection <= 'I')) { validData = calcExchangeAmt (amtExchanged, selection); } else(validData == false); { cout<<"Do you wish to continue? (Y for Yes / N for No)"; cin>>yesNo; } do { main(); } while ((yesNo =='y')||(yesNo == 'Y')); { system("cls"); } return 0; } this is the warning that im gettng: warning C4800: 'double' : forcing value to bool 'true' or 'false' (performance warning)

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  • Does this mimic perfectly a function template specialization?

    - by zeroes00
    Since the function template in the following code is a member of a class template, it can't be specialized without specializing the enclosing class. But if the compiler's full optimizations are on (assume Visual Studio 2010), will the if-else-statement in the following code get optimized out? And if it does, wouldn't it mean that for all practical purposes this IS a function template specialization without any performance cost? template<typename T> struct Holder { T data; template<int Number> void saveReciprocalOf(); }; template<typename T> template<int Number> void Holder<T>::saveReciprocalOf() { //Will this if-else-statement get completely optimized out if(Number == 0) data = (T)0; else data = (T)1 / Number; } //----------------------------------- void main() { Holder<float> holder; holder.saveReciprocalOf<2>(); cout << holder.data << endl; }

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  • Simplest way to automatically alter "const" value in Java during compile time

    - by Michael Mao
    Hi all: This is a question corresponds to my uni assignment so I am very sorry to say I cannot adopt any one of the following best practices in a short time -- you know -- assignment is due tomorrow :( link to Best way to alter const in Java on StackOverflow Basically the only task (I hope so) left for me is the performance tuning. I've got a bunch of predefined "const" values in my single-class agent source code like this: //static final values private static final long FT_THRESHOLD = 400; private static final long FT_THRESHOLD_MARGIN = 50; private static final long FT_SMOOTH_PRICE_IDICATOR = 20; private static final long FT_BUY_PRICE_MODIFIER = 0; private static final long FT_LAST_ROUNDS_STARTTIME = 90; private static final long FT_AMOUNT_ADJUST_MODIFIER = 5; private static final long FT_HISTORY_PIRCES_LENGTH = 10; private static final long FT_TRACK_DURATION = 5; private static final int MAX_BED_BID_NUM_PER_AUC = 12; I can definitely alter the values manually and then compile the code to give it another go around. But the execution time for a thorough "statistic analysis" usually requires over 2000 times of execution, which will typically lasts more than half an hour on my own laptop... So I hope there is a way to alter values using other ways than dig into the source code to change the "const" values there, so I can automatically distributed compiled code to other people's PC and let them run the statistic analysis instead. One other reason for a automatically value adjustment is that I can try using my own agent to defeat itself by choosing different "const" values. Although my values are derived from previous history and statistical results, they are far from the most optimized values. I hope there is a easy way so I can quickly adopt that so to have a good sleep tonight while the computer does everything for me... :) Any hints on this sort of stuff? Any suggestion is welcomed and much appreciated.

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  • Is it safe to reuse javax.xml.ws.Service objects

    - by Noel Ang
    I have JAX-WS style web service client that was auto-generated with the NetBeans IDE. The generated proxy factory (extends javax.xml.ws.Service) delegates proxy creation to the various Service.getPort methods. The application that I am maintaining instantiates the factory and obtains a proxy each time it calls the targetted service. Creating the new proxy factory instances repeatedly has been shown to be expensive, given that the WSDL documentation supplied to the factory constructor, an HTTP URI, is re-retrieved for each instantiation. We had success in improving the performance by caching the WSDL. But this has ugly maintenance and packaging implications for us. I would like to explore the suitability of caching the proxy factory itself. Is it safe, e.g., can two different client classes, executing on the same JVM and targetting the same web service, safely use the same factory to obtain distinct proxy objects (or a shared, reentrant one)? I've been unable to find guidance from either the JAX-WS specification nor the javax.xml.ws API documentation. The factory-proxy multiplicity is unclear to me. Having Service.getPort rather than Service.createPort does not inspire confidence.

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  • How/when to hire new programmers, and how to integrate them?

    - by Shaul
    Hiring new programmers, especially in a small company, can often present a Catch-22 situation. We have too much work to do, so we need to hire new programmers. But we can't hire new programmers now, because they will need mentoring and several months of learning curve in your industry/product/environment before they're useful, and none of the programmers has time to be a mentor to a new programmer, because they're all completely swamped with the current work load. That may be a slightly frivolous way of describing the situation, but nevertheless, it's difficult for a small company on a tight budget to justify hiring someone who is not only going to be unproductive for a long time, but will also take away from the performance of the current programmers. How have you dealt with this kind of situation? When is the best time to hire someone? What are the best tasks to assign to a new team member so that they can learn their way around your code base and start getting their hands dirty as quickly as possible? How do you get the new guy useful without bogging your existing programmers down in too much mentoring? Any comments & suggestions you have are much appreciated!

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  • Commit is VERY slow in my NHibernate / SQLite project

    - by Tom Bushell
    I've just started doing some real-world performance testing on my Fluent NHibernate / SQLite project, and am experiencing some serious delays when when I Commit to the database. By serious, I mean taking 20 - 30 seconds to Commit 30 K of data! This delay seems to get worse as the database grows. When the SQLite DB file is empty, commits happen almost instantly, but when it grows to 10 Meg, I see these huge delays. The database has 16 tables, averaging 10 columns each. One possible problem is that I'm storing a dozen or so IList members, but they are typically only 200 elements long. But this is a recent addition to Fluent NHibernate automapping, which stores each float in a single table row, so maybe that's a potential problem. Any suggestions on how to track this down? I suspect SQLite is the culprit, but maybe it's NHibernate? I don't have any experience with profilers, but am thinking of getting one. I'm aware of NHibernate Profiler - any recommendations for profilers that work well with SQLite? Here's the method that saves the data - it's just a SaveOrUpdate call and a Commit, if you ignore all the error handling and debug logging. public static void SaveMeasurement(object measurement) { Debug.WriteLine("\r\n---SaveMeasurement---"); // Get the application's database session var session = GetSession(); using (var transaction = session.BeginTransaction()) { try { session.SaveOrUpdate(measurement); } catch (Exception e) { throw new ApplicationException( "\r\n SaveMeasurement->SaveOrUpdate failed\r\n\r\n", e); } try { Debug.WriteLine("\r\n---Commit---"); transaction.Commit(); Debug.WriteLine("\r\n---Commit Complete---"); } catch (Exception e) { throw new ApplicationException( "\r\n SaveMeasurement->Commit failed\r\n\r\n", e); } } }

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  • How should I avoid memoization causing bugs in Ruby?

    - by Andrew Grimm
    Is there a consensus on how to avoid memoization causing bugs due to mutable state? In this example, a cached result had its state mutated, and therefore gave the wrong result the second time it was called. class Greeter def initialize @greeting_cache = {} end def expensive_greeting_calculation(formality) case formality when :casual then "Hi" when :formal then "Hello" end end def greeting(formality) unless @greeting_cache.has_key?(formality) @greeting_cache[formality] = expensive_greeting_calculation(formality) end @greeting_cache[formality] end end def memoization_mutator greeter = Greeter.new first_person = "Bob" # Mildly contrived in this case, # but you could encounter this in more complex scenarios puts(greeter.greeting(:casual) << " " << first_person) # => Hi Bob second_person = "Sue" puts(greeter.greeting(:casual) << " " << second_person) # => Hi Bob Sue end memoization_mutator Approaches I can see to avoid this are: greeting could return a dup or clone of @greeting_cache[formality] greeting could freeze the result of @greeting_cache[formality]. That'd cause an exception to be raised when memoization_mutator appends strings to it. Check all code that uses the result of greeting to ensure none of it does any mutating of the string. Is there a consensus on the best approach? Is the only disadvantage of doing (1) or (2) decreased performance? (I also suspect freezing an object may not work fully if it has references to other objects) Side note: this problem doesn't affect the main application of memoization: as Fixnums are immutable, calculating Fibonacci sequences doesn't have problems with mutable state. :)

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  • javascript pausing consistently. How do I find what is causing it to pause?

    - by pedalpete
    I've got a fairly ajax heavy site and I'm trying to tune the performance. I have a function that runs between 20 & 200 times, depending on the user. I'm outputting the time the function takes to execute via console.time in firefox. The function takes about 4-6ms to complete. The strange thing is that on my larger test with 200 or runs through that function, it runs through the first 31, then seems to pause for almost a second before completing the last 170 or so. However, that 'pause' doesn't show up in the console.time logs, and I'm not running any other functions, and the object that gets passed to the function looks the same as all other objects that get passed in. The function is called like this for (var s in thisGroup.events){ showEvent(thisGroup.events[s]) } so, I don't see how or why it would suddenly pause near the beginning. but only pause once and then continue through. The pause ALWAYS happens on the 31st time through the function. I've taken a close look at the 'thisGroup.events[s]' that it is being run through, and it looks like this for #31 "eventId":"5106", "sid":"68", "gid":"29", "uid":"70","type":"event", "startDate":"2010-03-22","startTime":"6:00 PM","endDate":"2010-03-22","endTime":"11:00 PM","durationLength":"5", "durationTime":"5:00", "note":"", "desc":"event" The event immediately after the pause, #32 looks like this "eventId":"5111", "sid":"68", "gid":"29", "uid":"71","type":"event", "startDate":"2010-03-22","startTime":"6:00 PM","endDate":"2010-03-22","endTime":"11:00 PM","durationLength":"5", "durationTime":"5:00", "note":"", "desc":"event" another event that runs through no problem looks like this "eventId":"5113", "sid":"68", "gid":"29", "uid":"72","type":"event", "startDate":"2010-03-22","startTime":"4:30 PM","endDate":"2010-03-22","endTime":"11:00 PM","durationLength":"6.5", "durationTime":"6:30", "note":"", "desc":"event" From the console outputs, it doesn't appear as there is anything hanging or taking up time in the function itself, as the console.time for each event including #31,32 is 4ms. Another strange thing here is that the total time running the for loop across the entire object is coming out as 1014ms which is right for 200 events at 4-6ms each. Any suggestions on how to find this 'pause'? I find it very interesting that it is consistently happening between #31 & #32 only!

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  • Algorithm to produce Cartesian product of arrays in depth-first order

    - by Yuri Gadow
    I'm looking for an example of how, in Ruby, a C like language, or pseudo code, to create the Cartesian product of a variable number of arrays of integers, each of differing length, and step through the results in a particular order: So given, [1,2,3],[1,2,3],[1,2,3]: [1, 1, 1] [2, 1, 1] [1, 2, 1] [1, 1, 2] [2, 2, 1] [1, 2, 2] [2, 1, 2] [2, 2, 2] [3, 1, 1] [1, 3, 1] etc. Instead of the typical result I've seen (including the example I give below): [1, 1, 1] [2, 1, 1] [3, 1, 1] [1, 2, 1] [2, 2, 1] [3, 2, 1] [1, 3, 1] [2, 3, 1] etc. The problem with this example is that the third position isn't explored at all until all combinations of of the first two are tried. In the code that uses this, that means even though the right answer is generally (the much larger equivalent of) 1,1,2 it will examine a few million possibilities instead of just a few thousand before finding it. I'm dealing with result sets of one million to hundreds of millions, so generating them and then sorting isn't doable here and would defeat the reason for ordering them in the first example, which is to find the correct answer sooner and so break out of the cartesian product generation earlier. Just in case it helps clarify any of the above, here's how I do this now (this has correct results and right performance, but not the order I want, i.e., it creates results as in the second listing above): def cartesian(a_of_a) a_of_a_len = a_of_a.size result = Array.new(a_of_a_len) j, k, a2, a2_len = nil, nil, nil, nil i = 0 while 1 do j, k = i, 0 while k < a_of_a_len a2 = a_of_a[k] a2_len = a2.size result[k] = a2[j % a2_len] j /= a2_len k += 1 end return if j > 0 yield result i += 1 end end UPDATE: I didn't make it very clear that I'm after a solution where all the combinations of 1,2 are examined before 3 is added in, then all 3 and 1, then all 3, 2 and 1, then all 3,2. In other words, explore all earlier combinations "horizontally" before "vertically." The precise order in which those possibilities are explored, i.e., 1,1,2 or 2,1,1, doesn't matter, just that all 2 and 1 are explored before mixing in 3 and so on.

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  • Mysql Server Optimization

    - by Ish Kumar
    Hi Geeks, We are having serious MySQL(InnoDB) performance issues at a moment when we do: (10-20) insertions on TABLE1 (10-20) updates on TABLE2 Note: Both above operations happens within fraction of a second. And this occurs every few (10-15) minutes. And all online users (approx 400-600) doing read operation on join of TABLE1 & TABLE2 every 1 second. Here is our mysql configuration info: http://docs.google.com/View?id=dfrswh7c_117fmgcmb44 Issues: Lot queries wait and expire later (saw it from phpmyadmin / processes). My poor MySQL server crashes sometimes Questions Q1: Any suggestions to optimize at MySQL level? Q2: I thinking to use persistent connections at application level, is it right? Info Added Later: Database Engine: InnoDB TABLE1 : 400,000 rows (inserting 8,000 daily) & TABLE2: 8,000 rows 1 second query: SELECT b.id, b.user_id, b.description, b.debit, b.created, b.price, u.username, u.email, u.mobile FROM TABLE1 b, TABLE2 u WHERE b.credit = 0 AND b.user_id = u.id AND b.auction_id = "12345" ORDER BY b.id DESC LIMIT 10; // there are few more but they are not so critical. Indexing is good, we are using them wisely. In above query all id's are indexed And TABLE1 has frequent insertions and TABLE2 has frequent updates.

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  • Help on understanding multiple columns on an index?

    - by Xaisoft
    Assume I have a table called "table" and I have 3 columns, a, b, and c. What does it mean to have a non-clustered index on columns a,b? Is a nonclustered index on columns a,b the same as a nonclustered index on columns b,a? (Note the order). Also, Is a nonclustered index on column a the same as a nonclustered index on a,c? I was looking at the website sqlserver performance and they had these dmv scripts where it would tell you if you had overlapping indexes and I believe it was saying that having an index on a is the same as a,b, so it is redundant. Is this true about indexes? One last question is why is the clustered index put on the primary key. Most of the time the primary key is not queried against, so shouldn't the clustered index be on the most queried column. I am probably missing something here like having it on the primary key speeds up joins? Great explanations. Should I turn this into a wiki and change the title index explanation?

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  • Count rows against to SQL server (2005) table?

    - by David.Chu.ca
    I have a simple question with two options to get count of rows in a SQL server (2005). I am using VS 2005. There are two options to get the count: SELECT id FROM Table1 WHERE dt >= startDt AND dt < endDt;; I get a list of ids from above call in cache and then I get count by List.Count. Another option is SELECT COUNT(*) FROM Table1 WHERE dt >= startDt AND dt < endDt; The above call will get the count directly. The issue is that I had several cases of exceptions with the second method: timeout. What I found is that the table1 is too big with millions of data. When I used the first option, it seems OK. I am confused by the fact that Count() takes more time than getting all the rows(is that true?). Not sure if the aggregation call with Count() would cause SQL server to create temporary table or cache on server side and it would result in slow performance when table is too big? I am not sure what is the best way to get the count?

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  • sem-dynamic cdn

    - by dwi kristianto
    i'm developing couple of websites using php (directory script, etc.) and wordpress as cms. i need to improve its performance, by using cdn for static files (css, js, images). the problem is, css and javascript files are generated on the fly. i did that due to yahoo and some expert advice to combine the files into one file. also changing basic color of css files. for the time being, i use couple of small vps but still its not fast enough. i already contact maxcdn and the support guy said that they dont have such kind of services. what i need is: a cdn that will serve the request from user/visitor and there's no file in local disk, the cdn will redirect/fetch it from another domain/server. in vps, it could be done easily using combination of .htaccess and php, but NOT in the cdn. most of cdn only support purely static files. is there any such cdn that will server semi-dynamic files?

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  • Stack usage with MMX intrinsics and Microsoft C++

    - by arik-funke
    I have an inline assembler loop that cumulatively adds elements from an int32 data array with MMX instructions. In particular, it uses the fact that the MMX registers can accommodate 16 int32s to calculate 16 different cumulative sums in parallel. I would now like to convert this piece of code to MMX intrinsics but I am afraid that I will suffer a performance penalty because one cannot explicitly intruct the compiler to use the 8 MMX registers to accomulate 16 independent sums. Can anybody comment on this and maybe propose a solution on how to convert the piece of code below to use intrinsics? == inline assembler (only part within the loop) == paddd mm0, [esi+edx+8*0] ; add first & second pair of int32 elements paddd mm1, [esi+edx+8*1] ; add third & fourth pair of int32 elements ... paddd mm2, [esi+edx+8*2] paddd mm3, [esi+edx+8*3] paddd mm4, [esi+edx+8*4] paddd mm5, [esi+edx+8*5] paddd mm6, [esi+edx+8*6] paddd mm7, [esi+edx+8*7] ; add 15th & 16th pair of int32 elements esi points to the beginning of the data array edx provides the offset in the data array for the current loop iteration the data array is arranged such that the elements for the 16 independent sums are interleaved.

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  • How to choose light version of databse system

    - by adopilot
    I am starting one POS (Point of sale) project. Targeting system is going to be written in C# .NET 2 WinForms and as main database server We are going to use MS-SQL Server. As we have a lot of POS devices in chain for one store I will love to have backend local data base system on each POS device. Scenario are following: When main server goes down!! POS application should continue working "off-line" with local database, until connection to main server come up again. Now I am in dilemma which local database is going to be most adoptable for me. Here is some notes for helping me point me in right direction: To be Light "My POS devices art usually old and suffering with performances" To be Free "I have a lot of devices and I do not wont additional cost beside main SQL serer" One day Ill love to try all that port on Mono and Linux OS. Here is what I've researched so far: Simple XML "Light but I am afraid of performance, My main table of items is average of 10K records" SQL-Expres "I am afraid that my POS devices is poor with hardware for SQLExpres, and also hard to install on each device and configure" Less known Advantage Database Server have free distribution of offline ADT system. DBF with extended Library,"Respect for good old DBFs but that era is behind Me with clipper and DBFs" MS Access Sqlite "Mostly like for now, but I am afraid how it is going to pair with MS SQL do they have same Data taypes". I know that in this SO is a lot of subjective data, but at least can someone recommended some others lite database system, or things that I shod most take attention before I choice database.

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  • Disposing underlying object from finalizer in an immutable object

    - by Juan Luis Soldi
    I'm trying to wrap around Awesomium and make it look to the rest of my code as close as possible to NET's WebBrowser since this is for an existing application that already uses the WebBrowser. In this library, there is a class called JSObject which represents a javascript object. You can get one of this, for instance, by calling the ExecuteJavascriptWithResult method of the WebView class. If you'd call it like myWebView.ExecuteJavascriptWithResult("document", string.Empty).ToObject(), then you'd get a JSObject that represents the document. I'm writing an immutable class (it's only field is a readonly JSObject object) called JSObjectWrap that wraps around JSObject which I want to use as base class for other classes that would emulate .NET classes such as HtmlElement and HtmlDocument. Now, these classes don't implement Dispose, but JSObject does. What I first thought was to call the underlying JSObject's Dispose method in my JSObjectWrap's finalizer (instead of having JSObjectWrap implement Dispose) so that the rest of my code can stay the way it is (instead of having to add using's everywhere and make sure every JSObjectWrap is being properly disposed). But I just realized if more than two JSObjectWrap's have the same underlying JSObject and one of them gets finalized this will mess up the other JSObjectWrap. So now I'm thinking maybe I should keep a static Dictionary of JSObjects and keep count of how many of each of them are being referenced by a JSObjectWrap but this sounds messy and I think could cause major performance issues. Since this sounds to me like a common pattern I wonder if anyone else has a better idea.

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  • ways to avoid global temp tables in oracle

    - by Omnipresent
    We just converted our sql server stored procedures to oracle procedures. Sql Server SP's were highly dependent on session tables (INSERT INTO #table1...) these tables got converted as global temporary tables in oracle. We ended up with aroun 500 GTT's for our 400 SP's Now we are finding out that working with GTT's in oracle is considered a last option because of performance and other issues. what other alternatives are there? Collections? Cursors? Our typical use of GTT's is like so: Insert into GTT INSERT INTO some_gtt_1 (column_a, column_b, column_c) (SELECT someA, someB, someC FROM TABLE_A WHERE condition_1 = 'YN756' AND type_cd = 'P' AND TO_NUMBER(TO_CHAR(m_date, 'MM')) = '12' AND (lname LIKE (v_LnameUpper || '%') OR lname LIKE (v_searchLnameLower || '%')) AND (e_flag = 'Y' OR it_flag = 'Y' OR fit_flag = 'Y')); Update the GTT UPDATE some_gtt_1 a SET column_a = (SELECT b.data_a FROM some_table_b b WHERE a.column_b = b.data_b AND a.column_c = 'C') WHERE column_a IS NULL OR column_a = ' '; and later on get the data out of the GTT. These are just sample queries, in actuality the queries are really complext with lot of joins and subqueries. I have a three part question: Can someone show how to transform the above sample queries to collections and/or cursors? Since with GTT's you can work natively with SQL...why go away from the GTTs? are they really that bad. What should be the guidelines on When to use and When to avoid GTT's

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  • When are SQL views appropriate in ASP.net MVC?

    - by sslepian
    I've got a table called Protocol, a table called Eligibility, and a Protocol_Eligibilty table that maps the two together (a many to many relationship). If I wanted to make a perfect copy of an entry in the Protocol table, and create all the needed mappings in the Protocol_Eligibility table, would using an SQL view be helpful, from a performance standpoint? Protocol will have around 1000 rows, Eligibility will have about 200, and I expect each Protocol to map to about 10 Eligibility rows and each Eligibility to map to over 100 rows in Protocol. Here's how I'm doing this with the view: var pel_original = (from pel in _documentDataModel.Protocol_Eligibility_View where pel.pid == id select pel); Protocol_Eligibility newEligibility; foreach (var pel_item in pel_original) { newEligibility = new Protocol_Eligibility(); newEligibility.Eligibility = (from pel in _documentDataModel.Eligibility where pel.ID == pel_item.eid select pel).First(); newEligibility.Protocol = newProtocol; newEligibility.ordering = pel_item.ordering; _documentDataModel.AddToProtocol_Eligibility(newEligibility); } And this is without the view: var pel_original = (from pel in _documentDataModel.Protocol_Eligibility where pel.Protocol.ID == id select pel); Protocol_Eligibility newEligibility; foreach (var pel_item in pel_original) { pel_item.EligibilityReference.Load(); newEligibility = new Protocol_Eligibility(); newEligibility.Eligibility = pel_item.Eligibility; newEligibility.Protocol = newProtocol; newEligibility.ordering = pel_item.ordering; _documentDataModel.AddToProtocol_Eligibility(newEligibility); }

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  • Can I automatically throw descriptive exceptions with parameter values and class feild information?

    - by Robert H.
    I honestly don't throw exceptions often. I catch them even less, ironically. I currently work in shop where we let them bubble up to avicode. For whatever reason, however, avicode isn't configured to capture some of the critical bits I need when these exceptions come bouncing back to my attention. Specifically, I'd like to see the parameter values and the class’s field data at the time of the exception. I’d guess with the large suite of .Net services that I could create a static method to crawl up the stack, gather these bits and store them in a string that I could stick in my exception message. I really don't are how long such a method would take to execute as performance is no longer a concern when I hit one of these scenarios. If it's possible, I'm sure someone has done it. If that's the case, I'm having a hard time finding it. I think any search containing "exception" brings back too many resutls. Anyway, can this be done? If so, some examples or links would be great. Thanks in advance for your time, Robert

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  • Automatic .NET code, nhibernate session, and LINQ datacontext clean-up?

    - by AverageJoe719
    Hi all, in my goal to adopt better coding practices I have a few questions in general about automatic handling of code. I have heard different answers both from online and talking with other developers/programmers at my work. I am not sure if I should have split them into 3 questions, but they all seem sort of related: 1) How does .NET handle instances of classes and other code things that take up memory? I recently found out about using the factory pattern for certain things like service classes so that they are only instantiated once in the entire application, but then I was told that '.NET handles a lot of that stuff automatically when mentioning it.' 2) How does Nhibernate's session handle automatic clean-up of un-used things? I've seen some say that it is great at handling things automatically and you should just use a session factory and that's it, no need to close it. But I have also read and seem many examples where people close the hibernate session. 3) How does LINQ's datacontext handle this? Most of the time I never .disposed my datacontext's and the app didn't see to take a performance hit (though I am not running anything super intensively), but it seems like most people recommend disposing of your datacontext after you are done with it. However, I have seen many many code examples where the dispose method is never called. Also in general I found it kind of annoying that you couldn't access even one-deep child related objects after disposing of the datacontext unless you explicity also grabbed them in the query. Thanks all. I am loving this site so far, I kind of get lost and spend hours just reading things on here. =)

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  • Maintaining a pool of DAO Class instances vs doing new operator

    - by Fazal
    we have been trying to benchmark our application performance in multiple way for sometime now. I always believed that object creation in java using Class.newInstance() was not slow (at least after 1.4 version of java). But we anyways did a test to use newInstance method vs mainitain an object pool of 1000 objects. We did about 200K iterations of loading data from DB using JDBC and populating these objects. I was amazed (even shocked) to see that newInstance code compared to object pool code was almost 10 times slower. These objects represent tables with about 50 fields and all string type. Can someone share there thoughts on this issue as now I am more confused if object pooling of atleast some DAO instances is a better option. The pool size as I see right now should be large enough to meet size of average requests. There is a flip side as my memory footprint will go up but I am beginning to wonder if this kind of idea makes sense atleast for some of the DAO entities representing tables of about 50 or more columns Please share your ideas and let me know if this has been tried by someone or am I missing some point here

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