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• Is it faster to use a complicated boolean to limit a ResultSet at the MySQL end or at the Java end?

  - by javanix

  Lets say I have a really big table filled with lots of data (say, enough not to fit comfortably in memory), and I want to analyze a subset of the rows. Is it generally faster to do: SELECT (column1, column2, ... , columnN) FROM table WHERE (some complicated boolean clause); and then use the ResultSet, or is it faster to do: SELECT (column1, column2, ... , columnN) FROM table; and then iterate over the ResultSet, accepting different rows based on a java version of your boolean condition? I think it comes down to whether the Java iterator/boolean evaluator is faster than the MySQL boolean evaluator.

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• jQuery: How to find elements *without* a class set

  - by Alan

  Hey jQuery clever peeps, Why does this fail... $( 'div.contactAperson input' ).not( 'input.hadFocus' ).focus(function() { $(this).attr('value', '' ); }); ...it's meant to sniff out input's that have not got the class .hadFocus and then when one of that subset receives focus it should zap the value to null. Right now, input values are always getting zapped -- the test .not( 'input.hadFocus' ) is failing to stop execution. Btw, preceding the above code is the following code, which is working fine: $( 'div.contactAperson input' ).focus(function() { $( this ).addClass( 'hadFocus' ); }); Thanks for any cleverness - cheers, -Alan

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• Manage duplicate jar files using ant and ivy.

  - by lawardy

  HI, I am using ant build script to build my java app and utilizing Ivy to manage its dependency. As my application is dependent/subset of other application(Main App), when running it, I set the classpath to point to lib jars of the Main App. As I tried to build the kit using ant and ivy, it includes/retrieve all the jars that is required as specified in ivy.xml The problem is, some of the jar files are duplicated with with jars file in the main app folders. Is there a way to set the classpath in build.xml to ignore retrieving jar files that already exist in the main app's lib folder. Thanks

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• Is it a good idea to use only a key to encrypt an entire (small) filesystem?

  - by Fernando Miguélez

  This question comes as part of my doubts presented on a broader question about ideas implementing a small encrypted filesystem on Java Mobile phones (J2ME, BlackBerry, Android). Provided the litte feedback received, considering the density of the question, I decided to divide those doubts into small questions. So to sum up I plan to "create" an encrypted filesystem for for mobile phones (with the help of BoucyCastle or a subset of JCE), providing an API that let access to them in a transparent way. Encryption would be carried out on a file basis (not blocks). My question is this: Is it a good idea to use only a simmetric key (maybe AES-256) to encrypt all the files (they wouldn't be that many, maybe tens of them) and store this key in a keystore (protected by a pin) or would you rather encrypt each file with an on-the-fly generated key stored alongside each file, encrypting that key with the "master" key stored on the keystore? What are the benefits/drawbacks of each approach?

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• will_paginate without use of activerecord

  - by truthSeekr

  I apologize if this is a trivial question or my understanding of rails is weak. I have 2 actions in my controller, index and refine_data. index fetches and displays all the data from a database table. refine_data weeds out unwanted data using regex and returns a subset of the data. Controller looks like: def index Result.paginate :per_page => 5, :page => params[:page], :order => 'created_at DESC' end def refine_data results = Result.all new_results = get_subset(results) redirect_to :action => 'index' end I would like to redirect the refine_data action to the same view (index) with new_results. As new_results are not from the database table (or model), how do I go about constructing my paginate?

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• Oracle, slow performance when using sub select

  - by Wyass

  I have a view that is very slow if you fetch all rows. But if I select a subset (providing an ID in the where clause) the performance is very good. I cannot hardcode the ID so I create a sub select to get the ID from another table. The sub select only returns one ID. Now the performance is very slow and it seems like Oracle is evaluating the whole view before using the where clause. Can I somehow help Oracle so SQL 2 and 3 have the same performance? I’m using Oracle 10g 1 slow select * from ci.my_slow_view 2 fast select * from ci.my_slow_view where id = 1; 3 slow select * from ci.my_slow_view where id in (select id from active_ids)

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• Multiple calculations on the same set of data: ruby or database?

  - by Pierre

  Hi, I have a model Transaction for which I need to display the results of many calculations on many fields for a subset of transactions. I've seen 2 ways to do it, but am not sure which is the best. I'm after the one that will have the least impact in terms of performance when data set grows and number of concurrent users increases. data[:total_before] = Transaction.where(xxx).sum(:amount_before) data[:total_after] = Transaction.where(xxx).sum(:amount_after) ... or transactions = Transaction.where(xxx) data[:total_before]= transactions.inject(0) {|s, e| s + e.amount_before } data[:total_after]= transactions.inject(0) {|s, e| s + e.amount_after } ... Which one should I choose? (or is there a 3rd, better way?) Thanks, P.

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• How to determine the inner context node within an XSLT select

  - by Marcus Rickert

  Hi there! I'm trying to determine a subset of nodes stored in the variable objs by using a user defined function cube:is_active: <xsl:variable name="active_cubes" select="$objs[cube:is_active(XXX) = 'TRUE']"/ Since the function does not allow a local context I'm required to pass it as a parameter (denoted by XXX). However, the usual suspects "." or "current()" do not work since they refer to context node of the surrounding block and NOT to the current element of objs which is evaluated. The only solution so far which DOES work is: XXX=SOME_CHILD_TAG/.. But this is really ugly since it depends on the existence of the child tag for the parent node to work correctly. Is there any other way? Thanks!

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• Entity update from ASP.NET MVC page with post to Edit action

  - by mare

  I have a form that posts back to /Edit/ and my action in controller looks like this: // // POST: /Client/Edit [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(Client client) My form includes a subset of Client entity properties and I also include a hidden field that holds an ID of the client. The client entity itself is provided via the GET Edit action. Now I want to do entity update but so far I've only been trying without first loading the entity from the DB. Because the client object that comes in POST Edit has everything it needs. I want to update just those properties on the entity in datastore. So far I've tried with Context.Refresh() and AttachTo() but with no success - I'm getting all sorts of exceptions. I inspected the entity object as it comes from the web form and it looks fine (it does have an ID and entered data) mapped just fine. If I do it with Context.SaveChanges() then it just inserts new row..

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• is it better to use a "natural" language to write code?

  - by M.H

  I recently saw a programming language called supernova and they said in the web page : The Supernova Programming language is a modern scripting language and the First one presents the concept of programming with direct Fiction Description using Clear subset of pure Human Language. and you can write code like: i want window and the window title is Hello World. i want button and button caption is Close. and button name is btn1. btn1 mouse click. instructions are you close window end of instructions my question is not about the language itself but it is that are we need such languages and did they make writing code easier or not?

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• Grouping records by subsets SQL

  - by Stacy

  I have a database with PermitHolders (PermitNum = PK) and DetailedFacilities of each Permit Holder. In the tblPermitDetails table there are 2 columns PermitNum (foreign Key) FacilityID (integer Foreign Key Lookup to Facility table). A permitee can have 1 - 29 items on their permit, e.i. Permit 50 can have a Boat Dock (FacID 4), a Paved walkway (FacID 17) a Retaining Wall (FacID 20) etc. I need an SQL filter/display whatever, ALL PERMIT #s that have ONLY FacIDs 19, 20, or 28, NOT ones that have those plus "x" others,....just that subset. I've worked on this for 4 days, would someone PLEASE help me? I HAVE posted to other BB but have not received any helpful suggestions.

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• Interface name as a Type

  - by user1889148

  I am trying to understand interfaces in Java and have this task to do which I am a stack with. It must be something easy, but I don't seem to see the solution. Interface contains a few methods, one of them should return true if all elements of this set are also in the set. I.e. public interface ISet{ //some methods boolean isSubsetOf(ISet x); } Then the class: public class myClass implements ISet{ ArrayList<Integer> mySet; public myClass{ mySet = new ArrayList<Integer>(); } //some methods public boolean isSubsetOf(ISet x){ //method body } } What do I need to write in method body? How do I check that the instance of myClass is a subset of ISet collection? I was trying to cast, but it gives an error: ArrayList<Integer> param = (ArrayList<Integer>)x; return param.containsAll(mySet);

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• static constants return instance of specific class in Flex?

  - by Sang

  So here's what I mean. Let's say I have a class ErrorMessages which holds all my error messages as static constants. So I could access them like ErrorMessages.PASSWORD_INVALID or ErrorMessage.PASSWORD_TOO_SHORT. I want to know if it is possible to have separate classes that hold subset of these constants and access them like ErrorMessages.PASSWORD.INVALID or ErrorMessages.PASSWORD.TOO_SHORT, etc. This way I can more structured static structure and makes it much easier to use autocomplete. I tried few different ways and couldn't figure out if this was possible..

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• How to use anonymous types with Netflix OData API

  - by obautista

  If I create this collection: IEnumerable<_TITLE> _titles = null; How can I set the result set from Netflix in this expression: _titles = from t in Titles where t.Id == "ApUFq" select new {t, t.Cast} I am getting: Cannot implicitly convert type 'System.Linq.IQueryable' to 'System.Collections.Generic.IEnumerable<_Title'. An explicit conversion exists (are you missing a cast?) I understand it's because I am using an anonymous type. _TITLE is a custom complex object I create that exposes a subset of Netflix properties. If I add "_TITLE" in front the of the "new" it says that my object does not implement IENUMBERABLE. If then _TITLE implements IENUMBERABLE, it says _TITLE does not contain a definition for ADD and still getting conversion error. Basically, I want to set the _TITLE properties with the data returned from Netflix. I have defined _TITLE to contain the fields I need, plus a collection of PERSON (for Cast).

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• Using Closure Properties to prove Regularity

  - by WATWF

  Here's a homework problem: Is L_4 Regular? Let L_4 = L*, where L={0^i1^i | i>=1}. I know L is non-regular and I know that Kleene Star is a closed operation, so my assumption is that L_4 is non-regular. However my professor provided an example of the above in which L = {0^p | p is prime}, which he said was regular by proving that L* was equal to L(000* + e) by saying each was a subset of one another (e in this case means the empty word). So his method involved forming a regex of 0^p, but how I can do that when I essentially have one already?

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• How to make sure a method returns an array, even when there is only one element in Ruby

  - by doctororange

  I have a Ruby method that searches an array of hashes and returns a subset of that array. def last_actions(type = 'all') actions = @actions if type == 'run' actions = actions.select {|a| a['type'] == "run" } end return actions end This works, except when there is only one action to return, in which case I don't think it is returning an array with one element, but just the element itself. This becomes problematic later. What's a good way to ensure it returns an array of 1 element in this case? Thanks.

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• Does any method exist quickly to detect valid range versions of used library

  - by daneel-yaitskov

  I'm a beginner Haskell programmer. I have written some useful code for the last six month. And I want to release a library from it. The code will use system installation cabal as any Haskell library. A library is released with cabal has a meta data file where there is a logical predicate from the libraries and their versions. A developer usually uses one set libraries. It tediously care a set of the sets libraries. How to know either my library is compiled successfully or not for some subset libraries?

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• is it better to use a "natural" language to write codes ?

  - by M.H

  I recently saw a programming language called supernova and they said in the web page : The Supernova Programming language is a modern scripting language and the First one presents the concept of programming with direct Fiction Description using Clear subset of pure Human Language. and you can write codes like : i want window and the window title is Hello World. i want button and button caption is Close. and button name is btn1. btn1 mouse click. instructions are you close window end of instructions my question is not about the language itself but it is that are we need such languages and did they make writing codes more easier or not ?

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• Performance of jquery visible

  - by Mark Steudel

  I have a bunch of checkboxes on a page, and I only show a subset of those checkboxes at a time. I then perform some action which loops through all of the checkboxes and sees if they are checked or not: e.g. $(".delete_items").click( function() { $('.checkboxes' ).each(function(){ //do stuff } } Then I was thinking, well since the user can never interact with the hidden checkboxes, that adding :visible to checkboxes would speed up the loop e.g. $(".delete_items").click( function() { $('.checkboxes :visible' ).each(function(){ //do stuff } } But I don't know if adding :visible adds more overhead. Any thoughts?

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• Even lighter than SQLite

  - by Richard Fabian

  I've been looking for a C++ SQL library implementation that is simple to hook in like SQLite, but faster and smaller. My projects are in games development and there's definitely a cutoff point between needing to pass the ACID test and wanting some extreme performance. I'm willing to move away from SQL string style queries, allowing it to be code driven, but I haven't found anything out there that provides SQL like flexibility while also preferring performance over the ACID test. I don't want to go reinventing the wheel, and the idea of implementing an SQL library on my own is quite daunting, even if it's only going to be simple subset of all the calls you could make. I need the basic commands (SELECT, MODIFY, DELETE, INSERT, with JOIN, and WHERE), not data operations (like sorting, min, max, count) and don't need the database to be atomic, or even enforce consistency (I can use a real SQL service while I'm testing and debugging).

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• R problems using rpart with 4000 records and 13 attributes

  - by josh

  I have attempted to email the author of this package without success, just wondering if anybody else has experienced this. I am having an using rpart on 4000 rows of data with 13 attributes. I can run the same test on 300 rows of the same data with no issue. When I run on 4000 rows, Rgui.exe runs consistently at 50% cpu and the UI hangs.... it will stay like this for at least 4-5hours if I let it run, and never exit or become responsive. here is the code I am using both on the 300 and 4000 size subset : train<-read.csv("input.csv",header=T) y<-train[,18] x<-train[,3:17] library(rpart) fit<-rpart(y~.,x) Is this a known limitation of rpart, am I doing something wrong? potential workarounds? any assistance appreciated

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• how to write regular expression to validate a string using regex in C#

  - by Charu

  I need to validate a user input based on condition. i wrote a regular expression to do so, but it's failing not sure why. Can somebody point where i am making mistake? Regex AccuracyCodeHexRegex = new Regex(@"^[PTQA]((0|8)[01234567]){2}$"); This is what i am trying to validate(If the string is a subset of these strings then it is valid): Phh, Thh, Qhh, Ahh where 'h' is a hex digit in the set {00, 80, 01, 81, 02, 82, 03, 83, 04, 84, 05, 85, 06, 86, 07, 87} Ex: P00 is valid P20 is not valid

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• Javascript: How to filter object array based on attributes?

  - by JGreig

  I have the following JavaScript JSON array of real estate home objects: var json = { 'homes' : [ { "home_id":"1", "price":"925", "sqft":"1100", "num_of_beds":"2", "num_of_baths":"2.0", }, { "home_id":"2", "price":"1425", "sqft":"1900", "num_of_beds":"4", "num_of_baths":"2.5", }, // ... (more homes) ... ]} var xmlhttp = eval('(' + json + ')'); homes = xmlhttp.homes; What I would like to do is be able to perform a filter on the object to return a subset of "home" objects. For example, I want to be able to filter based on: price, sqft, num_of_beds, and num_of_baths. Question: How can I perform something in javascript like the pseudo-code below: var newArray = homes.filter( price <= 1000 & sqft >= 500 & num_of_beds >=2 & num_of_baths >= 2.5); Note, the syntax does not have to be exactly like above. This is just an example.

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• Is there a .def file equicalent on Linux for controlling exported function names in a shared library

  - by morpheous

  I am building a shared library on Ubuntu 9.10. I want to export only a subset of my functions from the library. On the Windows platform, this would be done using a module definition ( .def) file which would contain a list of the external and internal names of the functions exported from the library. I have the following questions: How can I restrict the exported functions of a shared library to those I want (i.e. a .def file equivalent) Using .def files as an example, you can give a function an external name that is different from its internal name (useful for prevent name collisions and also redecorating mangled names etc) On windows I can use the EXPORT command (IIRC) to check the list of exported functions and addresses, what is the equivalent way to do this on Linux?

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• Accessing items from a dictionary using pickle efficiently in Python

  - by user248237

  I have a large dictionary mapping keys (which are strings) to objects. I pickled this large dictionary and at certain times I want to pull out only a handful of entries from it. The dictionary has usually thousands of entries total. When I load the dictionary using pickle, as follows: from cPickle import * # my dictionary from pickle, containing thousands of entries mydict = open(load('mypickle.pickle')) # accessing only handful of entries here for entry in relevant_entries: # find relevant entry value = mydict[entry] I notice that it can take up to 3-4 seconds to load the entire pickle, which I don't need, since I access only a tiny subset of the dictionary entries later on (shown above.) How can I make it so pickle only loads those entries that I have from the dictionary, to make this faster? Thanks.

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