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  • Duplicate partitioning key performance impact

    - by Anshul
    I've read in some posts that having duplicate partitioning key can have a performance impact. I've two tables like: CREATE TABLE "Test1" ( CREATE TABLE "Test2" ( key text, key text, column1 text, name text, value text, age text, PRIMARY KEY (key, column1) ... ) PRIMARY KEY (key, name,age) ) In Test1 column1 will contain column name and value will contain its corresponding value.The main advantage of Test1 is that I can add any number of column/value pairs to it without altering the table by just providing same partitioning key each time. Now my question is how will each of these table schema's impact the read/write performance if I've millions of rows and number of columns can be upto 50 in each row. How will it impact the compaction/repair time if I'm writing duplicate entries frequently?

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  • Creating a triple store query using SQL - how to find all triples that have a common predicate and o

    - by Ankur
    I have a database that acts like a triple store, except that it is just a simple MySQL database. I want to select all triples that have a common predicate and object. Info about RDF and triples I can't seem to work out the SQL. If I had just a single predicate and object to match I would do: select TRIPLE from TRIPLES where PREDICATE="predicateName" and OBJECT="objectName" But if I have a list (HashMap) of many pairs of (predicateName,objectName) I am not sure what I need to do. Please let me know if I need to provide more info, I am not sure that I have made this quite clear, but I am wary of providing too much info and confusing the issue.

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  • Git Pull works; Git push fails

    - by Michael
    I thought I set up my key pairs correctly -- I can do git pulls. I can do git commits. But when I do a git push, it counts objects, decompresses, then says: fatal: the remote end hung up unexpectedly. What's the issue here? I'm a super user, so it's not folder writable / readable access problems -- it must be the way I set up the encryption key pair... how do I debug this ... since git pull works?

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  • Matching process , issue with query

    - by Blerta Blerta
    i have this code which helps me match two different tables.. now, each of this tables, has a epos_id and a rbpos_id ! I have another table which has pairs of rbpos_id and epos_id, something like: id | epos_id | rbpos_id 1 a3566 465jd 2 hkiyb rbposi When i join this other table, i need to check this condition, i mean, the matching should be done, only and if, the epos_id and rbpos_id of the join i'm doing, have the same id,i mean, belong to the same row.. Here is my current query... Thanks! SELECT retailer.date, retailer.time, retailer.location, retailer.user_id,imovo.mobile_number ". "FROM retailer LEFT JOIN imovo ". " ON addtime(retailer.time, '0:0:50')>imovo.time AND retailer.time <imovo.time AND retailer.date=imovo.date

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  • How do I get Mathematica to thread a 2-variable function over two lists, using functional programmin

    - by Leah Wrenn Berman
    Lets say I have a function f[x_, y_], and two lists l1, l2. I'd like to evaluate f[x,y] where x runs over the list l1 and y runs over the list l2, and I'd like to do it without having to make all pairs of the form {l1[[i]],l2[[j]]}. (Motivation: I'm trying to implement some basic Haskell programs in Mathematica. In particular, I'd like to be able to code the Haskell program isMatroid::[[Int]]->Bool isMatroid b =and[or[sort(union(xs\\[x])[y]'elem'b|y<-ys]|xs<-b,ys<-b, xs<-x] I think I can do the rest of it, if I can figure out the original question, but I'd like the code to be Haskell-like. Any suggestions for implementing Haskell-like code in Mathematica would be appreciated.)

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  • Parsing a dynamic value with Lift-JSON

    - by Surya Suravarapu
    Let me explain this question with an example. If I have a JSON like the following: {"person1":{"name": "Name One", "address": {"street": "Some Street","city": "Some City"}}, "person2":{"name": "Name Two", "address": {"street": "Some Other Street","city": "Some Other City"}}} [There is no restriction on the number of persons, the input JSON can have many more persons] I could extract this JSON to Persons object by doing var persons = parse(res).extract[T] Here are the related case classes: case class Address(street: String, city: String) case class Person(name: String, address: Address, children: List[Child]) case class Persons(person1: Person, person2: Person) Question: The above scenario works perfectly fine. However the need is that the keys are dynamic in the key/value pairs. So in the example JSON provided, person1 and person2 could be anything, I need to read them dynamically. What's the best possible structure for Persons class to account for that dynamic nature.

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  • Is there an equivalent for the Zip function in Clojure Core or Contrib?

    - by John Kane
    In Clojure, I want to combine two lists to give a list of pairs, > (zip '(1 2 3) '(4 5 6)) ((1 4) (2 5) (3 6)) In Haskell or Ruby the function is called zip. Implementing it is not difficult, but I wanted to make sure I wasn't missing a function in Core or Contrib. There is a zip namespace in Core, but it is described as providing access to the Zipper functional technique, which does not appear to be what I am after. Is there an equivalent function for combining 2 or more lists, in this way, in Core? If there is not, is it because there is an idiomatic approach that renders the function unneeded?

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  • resizing arrays when close to memory capacity

    - by user548928
    So I am implementing my own hashtable in java, since the built in hashtable has ridiculous memory overhead per entry. I'm making an open-addressed table with a variant of quadratic hashing, which is backed internally by two arrays, one for keys and one for values. I don't have the ability to resize though. The obvious way to do it is to create larger arrays and then hash all of the (key, value) pairs into the new arrays from the old ones. This falls apart though when my old arrays take up over 50% of my current memory, since I can't fit both the old and new arrays in memory at the same time. Is there any way to resize my hashtable in this situation Edit: the info I got for current hashtable memory overheads is from here How much memory does a Hashtable use? Also, for my current application, my values are ints, so rather than store references to Integers, I have an array of ints as my values.

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  • Order database results by bayesian rating

    - by One Trick Pony
    I'm not sure this is even possible, but I need a confirmation before doing it the "ugly" way :) So, the "results" are posts inside a database which are stored like this: the posts table, which contains all the important stuff, like the ID, the title, the content the post meta table, which contains additional post data, like the rating (this_rating) and the number of votes (this_num_votes). This data is stored in pairs, the table has 3 columns: post ID / key / value. It's basically the WordPress table structure. What I want is to pull out the highest rated posts, sorted based on this formula: br = ( (avg_num_votes * avg_rating) + (this_num_votes * this_rating) ) / (avg_num_votes + this_num_votes) which I stole form here. avg_num_votes and avg_rating are known variables (they get updated on each vote), so they don't need to be calculated. Can this be done with a mysql query? Or do I need to get all the posts and do the sorting with PHP?

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  • Revisions: algorithm and data structure

    - by SODA
    Hi, I need ideas for structuring and processing data with revisions. For example, I have a database of objects (e.g. cars). Each object has a number of properties, which can be arbitrary, so there's no a set schema to describe these objects. These objects are probably saved as key-value pairs. Now I need to change property of an object. I don't want to completely rewrite it - I want to be able to go back and see history of changes to these properties, that's why I want to add new property and keep the old one (so I guess a timestamp would do the job of telling which property is the latest). At the same time I want to be able to get info about any object in a snap, with only latest versions of each of the properties. Any ideas what would be the best approach? At least please point me in the right direction. Thanks!

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  • Implement dictionary using java

    - by ahmad
    Task Dictionary ADT The dictionary ADT models a searchable collection of key-element entries Multiple items with the same key are allowed Applications: word-definition pairs Dictionary ADT methods: find(k): if the dictionary has an entry with key k, returns it, else, returns null findAll(k): returns an iterator of all entries with key k insert(k, o): inserts and returns the entry (k, o) remove(e): remove the entry e from the dictionary size(), isEmpty() Operation Output Dictionary insert(5,A) (5,A) (5,A) insert(7,B) (7,B) (5,A),(7,B) insert(2,C) (2,C) (5,A),(7,B),(2,C) insert(8,D) (8,D) (5,A),(7,B),(2,C),(8,D) insert(2,E) (2,E) (5,A),(7,B),(2,C),(8,D),(2,E) find(7) (7,B) (5,A),(7,B),(2,C),(8,D),(2,E) find(4) null (5,A),(7,B),(2,C),(8,D),(2,E) find(2) (2,C) (5,A),(7,B),(2,C),(8,D),(2,E) findAll(2) (2,C),(2,E) (5,A),(7,B),(2,C),(8,D),(2,E) size() 5 (5,A),(7,B),(2,C),(8,D),(2,E) remove(find(5)) (5,A) (7,B),(2,C),(8,D),(2,E) find(5) null (7,B),(2,C),(8,D),(2,E) Detailed explanation: NO Specific requirements: please Get it done i need HELP !!!

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  • Drive space hungry NoSQL's databases

    - by forum_inquisitor
    I've tested NoSQL databases like CouchDB, MongoDB and Cassandra and observed tendence to absorbing very large amount of drive space relative to inserted key-value pairs. When comparing CouchDB and MySQL schemaless databases CouchDB is consuming much more drive space than MySQL. I know about that key-value DBs by default are versioning and have long uuid and need key optimalisation - the comparison was between about 15 mln rows in MySQL and 1-5 mln documents listed NoSQL DB's. My question is : Is there any NoSQL with good compaction / compression of data? So that I can have NoSQL database with a size closer to 5GB than 50GB?

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  • Code Igniter - URL Rewrite

    - by André Alçada Padez
    Hey, i'm trying to get a project to work, but i am having trouble with the rewrite module. I'm running Wamp over Windows XP. I changed httpd.conf to change the root of localhost to: DocumentRoot "C:/wamp/www/project/docroot/" I have htaccess RewriteEngine On RewriteBase / my Apache has the rewrite module Activated. my base_url() in config.php is 'http://localhost/' in routes.php i have: $route['default_controller'] = "home"; $route['our-recipes'] = "recipes"; and more pairs when i point the browser to http://localhost/ i get the homepage of my site, but when i click on any internal link like to 'our-recipes' it loads but i get the same homepage, with the new url on the location bar. if i try to access 'http://localhost/recipes' i get the same result. this is my folder structure: Can anyone please solve this for me??

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  • How to roll my own index in c#?

    - by bill seacham
    I need a faster way to create an index file. The application generates pairs of items to be indexed. I currently add each pair as it is generated to a sorted dictionary and then write it out to a disk file. This works well until the number of items added exceeds one million, at which time it slows to the point that is unacceptable. There can be as many as three million data items to be indexed. I prefer to avoid a database because I do not want to significantly increase the size of the deployment package, which is now less than one-half of one megabyte. I tried Access but it is even slower than the sorted dictionary -if it had an efficient bulk load utility then that might work, but I do not find such a tool for Access. Is there a better way to roll my own index?

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  • Split a map using Groovy

    - by Tihom
    I want to split up a map into an array of maps. For example, if there is a map with 25 key/value pairs. I want an array of maps with no more than 10 elements in each map. How would I do this in groovy? I have a solution which I am not excited about, is there better groovy version: static def splitMap(m, count){ if (!m) return def keys = m.keySet().toList() def result = [] def num = Math.ceil(m?.size() / count) (1..num).each { def min = (it - 1) * count def max = it * count > keys.size() ? keys.size() - 1 : it * count - 1 result[it - 1] = [:] keys[min..max].each {k -> result[it - 1][k] = m[k] } } result } m is the map. Count is the max number of elements within the map.

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  • How to extract a couple marked strings from a line (python)

    - by GoJian
    My Friends, I spent quite some time on this one... but cannot yet figure out a better way to do it. I am coding in python, by the way. So, here is a line of text in a file I am working with, for example: "ref|ZP_01631227.1| 3-dehydroquinate synthase [Nodularia spumigena CCY9414]..." How can I extract the two strings "ZP_01631227.1" and "Nodularia spumigena CCY9414" from the line? The pairs of "| |" and brackets are like markers so we know we want to get the strings in between the two... I guess I can probably loop over all the characters in the line and do it the hard way. It just takes so much time... Wondering if there is a python library or other smart ways to do it nicely? Thanks to all!

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  • Efficient most common suffix algorithm?

    - by taw
    I have a few GBs worth of strings, and for every prefix I want to find 10 most common suffixes. Is there an efficient algorithm for that? An obvious solution would be: Store sorted list of <string, count> pairs. Identify by binary search extent for prefix we're searching. Find 10 highest counts in this extent. Possibly precompute it for all short prefixes, so it doesn't ever need to look at large portion of data. I'm not sure if that would actually be efficient at all. Is there a better way I overlooked? Answers must be real time, but it can take as much preprocessing as necessary.

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  • Returning messages in Smalltalk

    - by Zachary
    I have a Dictionary of objects I have created in smalltalk, which I am iterating over by enumerating it based on the key/value pairs. For value object in the dictionary, I am calling a method on that object. Based on certain conditions, I would like for this object to be able to add a new member to dictionary, and possibly delete another one. I've been looking at the 'Perform' and 'Messages' facilities in Smalltalk, but I'm not sure if it is even possible to do what I'm trying to do - is it possible to return a message (or multiple messages), which another object can process and perform? For example, could my method return 'removeKey: 19' and 'add object' at the same time? I am using GNU Smalltalk, if it matters.

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  • Java, JavaCC: How to check if a char (or char pair) is inside a given UTF32 range?

    - by java.is.for.desktop
    Hello, everyone! I am referring to the XML 1.1 spec. Look at the definition of NameStartChar: NameStartChar ::= ":" | [A-Z] | "_" | [a-z] | [#xC0-#xD6] | [#xD8-#xF6] | [#xF8-#x2FF] | [#x370-#x37D] | [#x37F-#x1FFF] | [#x200C-#x200D] | [#x2070-#x218F] | [#x2C00-#x2FEF] | [#x3001-#xD7FF] | [#xF900-#xFDCF] | [#xFDF0-#xFFFD] | [#x10000-#xEFFFF] If I interpret this correctly, the last range (#x10000-#xEFFFF) goes beyond the UTF16 range of Java's char type. So it must be UTF32, right? So, I need to check pairs of char against this range, instead of single chars, right? My questions are: How do I check for such character ranges using standard Java methods? How is it possible to define such ranges in JavaCC? JavaCC complains about \u10000 and \uEFFFF Thank you! NOTE: Don't worry, I am not trying to write an own XML-parser. I need those character ranges for other reasons.

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  • ASP.NET profile deletion

    - by Ben Aston
    We use the ASP.NET profile subsystem to associate key-value pairs of information with users. I am implementing functionality for the deletion of users. I have been using the ProfileManager.DeleteProfile(string userName) method, but I have noticed that this leaves a row in the aspnet_Users table in the aspnetdb database we use to store the profile information. Clearly, I could manipulate the database directly, but I am reluctant to do so. What is the best way to ensure all information assocaited with a user is deleted from the aspnetdb? PS: there is a tantalising Membership.DeleteUser(string userName, bool deleteEverything) method, but this returns a database connection error. A web.config issue?

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  • C# Linq: Restructuring object

    - by Ben
    I'd like to take an object like this: SortedList<string, SortedList<int, SortedList<DateTime, double>>> Data and, for a given 'int' value (key of first nested sorted list), restructure it like this: SortedList<DateTime, SortedList<string, double>> or, better yet, this: SortedList<DateTime, double[]> where each 'double[]' has as many elements as there are KeyValue pairs in the SortedList. I'm guessing Linq is the way to go, but can't figure it out. Thanks for any suggestions.

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  • Ruby/RoR: calling original method via super()?

    - by fearless_fool
    In a RoR app, I want to specialize ActiveRecord's update_attributes() method in one of my models, extracting some of the attributes for special handling and passing the rest of them to the original update_attributes() method. The details: class Premise < ActiveRecord::Base ... def update_attributes(attrs) attrs.each_pair do |key, val| unless has_attribute?(key) do_special_processing(key, val) attrs.delete(key) end end # use original update_attributes() to process non-special pairs super.update_attributes(attrs) end ... end The call to super.update_attributes(attr) raises an error: undefined method `update_attributes' for true:TrueClass ... which makes me suspect I really don't understand the super keyword in Ruby. What am I missing? Specifically, how do I call the original update_attributes() method?

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  • How to effectively clip the amount of entries in a dictionary?

    - by reinier
    I had a List<myClass> myList for storing a list of items. When I had to clip this (discard any amount of items above some threshold) I used: myList.RemoveRange(threshold, myList.Count - threshold); where threshold is the max amount of things the list can contain Now I've upgraded the datatype to a Dictionary<key, myClass> myDictionary How can I basically do the same: Discard all entries above some threshold. (It doesn't matter which ones are discarded) I guess I could foreach through the keys collection and manually delete all keys/value pairs. But I was hoping there was a more elegant solution.

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  • Insert new row with data computed from other rows

    - by Tyler McHenry
    Suppose I have a MySQL table called MyTable, that looks like this: +----+------+-------+ | Id | Type | Value | +----+------+-------+ | 0 | A | 1 | | 0 | B | 1 | | 1 | A | 2 | | 1 | B | 3 | | 2 | A | 5 | | 2 | B | 8 | +----+------+-------+ And, for each Id, I want to insert a new row with type C whose Value is the sum of the type A and B values for the rows of the same Id. The primary key on this table is (Id, Type), so there's no question of duplication of Id,Type pairs. I can create the rows I want with this query: SELECT MyTable_A.Id AS Id, 'C' AS Type, (A_Val + B_Val) AS Value FROM (SELECT Id, Value AS A_Val FROM MyTable WHERE Type='A') AS MyTable_A JOIN (SELECT Id, Value AS B_Val FROM MyTable WHERE Type='B') AS MyTable_B ON MyTable_A.Id = MyTable_B.Id Giving: +----+------+-------+ | Id | Type | Value | +----+------+-------+ | 0 | C | 2 | | 1 | C | 5 | | 2 | C | 13 | +----+------+-------+ But the question is: How do I use this result to insert the generated type-C rows into MyTable? Is there a relatively simple way to do this with a query, or do I need to write a stored procedure? And if the latter, guidance would be helpful, as I'm not too well versed in them.

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  • Enums,use in switch case

    - by WPS
    Hi, I have an Enum defined which contains method return type like "String",Float,List,Double etc. I will be using it in switch case statements. For example my enum is public enum MethodType { DOUBLE,LIST,STRING,ARRAYLIST,FLOAT,LONG; } In a property file, I've key value pairs as follows. Test1=String Test2=Double In my code I'm getting the value for the key. I need to use the VALUE in Switch Case to Determine the Type and based on that I've to implement some logic. For example something like this switch(MethodType.DOUBLE){ case DOUBLE: //Dobule logic } Can someone please help me to implement this?

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