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Archive for 2013年9月

Public bookmarks 09/29/2013 (p.m.)


    • Scala is now used in a rapidly increasing number of open source projects and companies. It provides the core infrastructure for sites such as Twitter, LinkedIn, Foursquare, Tumblr, and Klout.
    • Write your own tests! For this assignment, we don’t give you tests but instead the FunSetSuite.scala file contains hints on how to write your own tests for the assignment.
      • Android support: Integrated Tools

          

           

        • Action to obtain a screenshot from the device.
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        • Integrated 9-patch editor.
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        • New UI for viewing the list of connected devices in the Android toolwindow.
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        • Support for filtering by package name in logcat.

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Public bookmarks 09/29/2013 (a.m.)


    • The F-Droid Repository is an easily-installable catalogue of FOSS (Free and Open Source Software) applications for the Android platform. The server contains the details of multiple versions of each application, and the Android client makes it easy to browse, install them onto your device, and keep track of updates.

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Public bookmarks 09/28/2013 (p.m.)


    • Let’s face it, writing MongoDB validation, casting and business logic boilerplate is a drag. That’s why we wrote Mongoose.

      var mongoose = require('mongoose'); mongoose.connect('mongodb://localhost/test');  var Cat = mongoose.model('Cat', { name: String });  var kitty = new Cat({ name: 'Zildjian' }); kitty.save(function (err) {   if (err) // ...   console.log('meow'); });

      Mongoose provides a straight-forward, schema-based solution to modeling your application data and includes built-in type casting, validation, query building, business logic hooks and more, out of the box.

    • $natural hint is telling mongo to ignore indexes on queries, it has nothing with insertions.
       please note that you cannot turn off the indexes for period of time.
       If you want to speed up your insertions, dropping your indexes is an option but it will affect your queries. a better option is to change the write concerns setting:
       for instance, "Unacknowledged" will make the insertion faster as it won’t wait for mongod to confirms the receipt of the write operation. I guess that the downside is clear.
       take a look here: http://docs.mongodb.org/manual/core/write-concern/

        

      About indexes, it’s never a good idea to have indexes that you don’t need as they are slowing down insertions (as you already know) and they are biting your machine memory.

        

      At the documentation, it is recommended to use capped collections to speed up the writes, you may want to consider it.

    • How do write operations affect indexes?

       

      Any write operation that alters an indexed field requires an update to the index in addition to the document itself. If you update a document that causes the document to grow beyond the allotted record size, then MongoDB must update all indexes that include this document as part of the update operation.

       

      Therefore, if your application is write-heavy, creating too many indexes might affect performance.

      • A covered query is a query in which:

         

           

        • all the fields in the query are part of an index, and
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        • all the fields returned in the results are in the same index.
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        Because the index “covers” the query, MongoDB can both match the query conditions and return the results using only the index; MongoDB does not need to look at the documents, only the index, to fulfill the query. An index can also cover an aggregation pipeline operation on unsharded collections.

    • To determine whether a query is a covered query, use the explain() method. If the explain() output displays true for the indexOnly field, the query is covered by an index, and MongoDB queries only that index to match the query and return the results.
    • $slice (projection)

       

       

       $slice

       

      The $slice operator controls the number of items of an array that a query returns. For information on limiting the size of an array during an update with $push, see the $slice modifier instead.

       

      Consider the following prototype query:

       

      db.collection.find( { field: value }, { array: {$slice: count } } ); 

       

       

      This operation selects the document collection identified by a field named field that holds value and returns the number of elements specified by the value of count from the array stored in the array field. If count has a value greater than the number of elements in array the query returns all elements of the array.

       

      $slice accepts arguments in a number of formats, including negative values and arrays. Consider the following examples:

       

      db.posts.find( {}, { comments: { $slice: 5 } } )

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Public bookmarks 09/25/2013 (p.m.)


    • MVC General Concepts:
       
      To quickly review, MVC is a compound pattern meaning several patterns comprise this architectural pattern. The Model represents our application’s state. Remember, objects have state (properties) and behaviors (methods). And so applications have state (the model). In essence, models are just big name-value objects that dispatch events when its state changes. Views are the things you see and interact with. They bind to the model by registering themselves as observers.When the model changes, the  view is notified and it updates itself. When a user interacts with the view, it sends events to a Controller. The controller is responsible for handling the input logic. It interprets the user gestures, updates the model, and may send messages back to the view. Below is a typical MVC diagram showing this relationship.

       

  • tags: jira import csv

    • The JIRA Importers plugin, which is bundled with JIRA, allows you to import your data from a comma-separated value (CSV) file. CSV files are text files representing tabulated data and are supported by most applications that handle tabulated data (for e.g. Microsoft Excel, databases, etc.).

  • tags: aws cloud management

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Public bookmarks 09/25/2013 (a.m.)

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Public bookmarks 09/23/2013 (a.m.)


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Public bookmarks 09/21/2013 (p.m.)


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