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• Best practice PHP Form Action

  - by Rob

  Hi there i've built a new script (from scratch not a CMS) and i've done alot of work on reducing memory usage and the time it takes for the page to be displayed (caching HTML etc) There's one thing that i'm not sure about though. Take a simple example of an article with a comments section. If the comment form posts to another page that then redirects back to the article page I won't have the problem of people clicking refresh and resending the information. However if I do it that way, I have to load up my script twice use twice as much memory and it takes twice as long whilst i'm still only displaying the page once. Here's an example from my load log. The first load of the article is from the cache, the second rebuilds the page after the comment is posted. Example 1 0 queries using 650856 bytes of memory in 0.018667 - domain.com/article/1/my_article.html 9 queries using 1325723 bytes of memory in 0.075825 - domain.com/article/1/my_article/newcomment.html 0 queries using 650856 bytes of memory in 0.029449 - domain.com/article/1/my_article.html Example 2 0 queries using 650856 bytes of memory in 0.023526 - domain.com/article/1/my_article.html 9 queries using 1659096 bytes of memory in 0.060032 - domain.com/article/1/my_article.html Obviously the time fluctuates so you can't really compare that. But as you can see with the first method I use more memory and it takes longer to load. BUT the first method avoides the refresh problem. Does anyone have any suggestions for the best approach or for alternative ways to avoid the extra load (admittadely minimal but i'd still like to avoid it) whilst also avoiding the refresh problem?

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• Best practice way to handle variable content margin?

  - by Aithne

  Ok, so a quick site that I am throwing together for a friend has about 20 static pages. Each one with a small amount of content. the div Container contains, well, the div Content, and the div Content contains, obviously, the content that changes on each page. Now, depending on the length of the content, I want a different margin at the top. The less content, then the larger the margin. Simply an aesthetic choice. For example, if the content almost fills the static sized container, there is less padding, but a 1 line page of content might be 1/3 of the way down the static container. Centering the content in the div wont do, as that creates too large of a margin. Whats the best way to handle this? A new class for each content with a different margin? A new Id, so that it is in its own special div positioned or margined differently? Inline css on each page to override the standard css for div Content? A differnt spacer div inside Container before Content on each page? Some sort of scripting along the lines of margin of Content = (ContainerHeight - ContentHeight) / 3? Whats the acceptable way of doing this? I don't want to get into bad habits.

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• What is best practice about having one-many hibernate

  - by Patrick

  Hi all, I believe this is a common scenario. Say I have a one-many mapping in hibernate Category has many Item Category: @OneToMany( cascade = {CascadeType.ALL},fetch = FetchType.LAZY) @JoinColumn(name="category_id") @Cascade( value = org.hibernate.annotations.CascadeType.DELETE_ORPHAN ) private List<Item> items; Item: @ManyToOne(targetEntity=Category.class,fetch=FetchType.EAGER) @JoinColumn(name="category_id",insertable=false,updatable=false) private Category category; All works fine. I use Category to fully control Item's life cycle. But, when I am writing code to update Category, first I get Category out from DB. Then pass it to UI. User fill in altered values for Category and pass back. Here comes the problem. Because I only pass around Category information not Item. Therefore the Item collection will be empty. When I call saveOrUpdate, it will clean out all associations. Any suggestion on what's best to address this? I think the advantage of having Category controls Item is to easily main the order of Item and not to confuse bi-directly. But what about situation that you do want to just update Category it self? Load it first and merge? Thank you.

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• Best practice accessing an array set within a class

  - by user350599

  I have created a basic class for a customer. I haven't done this before and want to know the best way to access the data. Should I have a get() method for every field in the customer array or should I simply pass the customer array back and access with the page. i.e. Just return the array class Customer { protected $id; protected $customer; public function __construct($customer_id) { $this->id = $customer_id; $this->set_customer(); } protected function set_customer() { $query = mysql_query("SELECT * FROM customer WHERE id = '$this->id'"); $this->customer = mysql_fetch_row($query); } public function get_customer() { return $this->customer; } } versus create a method for each item in the array class Customer { protected $id; protected $customer; public function __construct($customer_id) { $this->id = $customer_id; $this->set_customer(); } protected function set_customer() { $query = mysql_query("SELECT * FROM customer WHERE id = '$this->id'"); $this->customer = mysql_fetch_row($query); } public function get_customer_name() { return $this->customer->customer_name; } ... ... } versus option 3 based on Tobias' feedback: (not sure if syntax is correct) class Customer { protected $id; protected $customer; public function __construct($customer_id) { $this->id = $customer_id; return $this->set_customer(); } protected function set_customer() { $query = mysql_query("SELECT * FROM customer WHERE id = '$this->id'"); return mysql_fetch_row($query); } }

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• Best practice to hide/encrypt email adress in webpage

  - by Sebi

  I couldn't find a similar question, that's why here it is: Whats the best way to hide or encrypt an email link in a website, so that a crawler can't read it, but the user can nevertheless click it? I don't want to conufse the users by typing the email like this: john (at) mail.com or similar ways. (and i think this kind of links can nevertheless read by crawlers?) I also tried things like that: <script>// <![CDATA[eval(unescape('%76%61%72%20%73%3D%27%61%6D%6C%69%6F%74%72%3A%62%61%40%65%64%61%6E%6F%6C%2E%69%27%3B%76%61%72%20%72%3D%27%27%3B%66%6F%72%28%76%61%72%20%69%3D%30%3B%69%3C%73%2E%6C%65%6E%67%74%68%3B%69%2B%2B%2C%69%2B%2B%29%7B%72%3D%72%2B%73%2E%73%75%62%73%74%72%69%6E%67%28%69%2B%31%2C%69%2B%32%29%2B%73%2E%73%75%62%73%74%72%69%6E%67%28%69%2C%69%2B%31%29%7D%64%6F%63%75%6D%65%6E%74%2E%77%72%69%74%65%28%27%3C%61%20%68%72%65%66%3D%22%27%2B%72%2B%27%22%3E%4F%62%65%72%70%61%72%6C%65%69%74%65%72%3C%2F%61%3E%27%29%3B'))]]></script> but i heard this can also be read by crawler and it isn't really good practices are ther any common approaches?

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• Best practice on structuring asynchronous mailers (using Sidekiq)

  - by gbdev

  Just wondering what's the best way to go about structuring asynchronous mailers in my Rails app (using Sidekiq)? I have one ActionMailer class with multiple methods/emails... notifier.rb: class Notifier < ActionMailer::Base default from: "\"Company Name\" <[email protected]>" default_url_options[:host] = Rails.env.production? ? 'domain.com' : 'localhost:5000' def welcome_email(user) @user = user mail to: @user.email, subject: "Thanks for signing up!" end ... def password_reset(user) @user = user @edit_password_reset_url = edit_password_reset_url(user.perishable_token) mail to: @user.email, subject: "Password Reset" end end Then for example, the password_reset mail is sent in my User model by doing... user.rb: def deliver_password_reset_instructions! reset_perishable_token! NotifierWorker.perform_async(self) end notifier_worker.rb: class NotifierWorker include Sidekiq::Worker sidekiq_options queue: "mail" def perform(user) Notifier.password_reset(user).deliver end end So I guess I'm wondering a couple things here... Is it possible to define many "perform" actions in one single worker? By doing so I could keep things simple (one notifier/mail worker) as I have it and send many different emails through it. Or should I create many workers? One for each mailer (e.g. WelcomeEmailWorker, PasswordResetWorker, etc) and just assign them all to use the same "mail" queue with Sidekiq. I know it works as it is, but should I break out each of those mail methods (welcome_email, password_reset, etc) into individually mailer classes or is it ok to have them all under one class like Notifier? Really appreciate any advice here. Thanks!

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• MongoDB usage best practices

  - by andresv

  The project I'm working on uses MongoDB for some stuff so I'm creating some documents to help developers speedup the learning curve and also avoid mistakes and help them write clean & reliable code. This is my first version of it, so I'm pretty sure I will be adding more stuff to it, so stay tuned! C# Official driver notes The 10gen official MongoDB driver should always be referenced in projects by using NUGET. Do not manually download and reference assemblies in any project. C# driver quickstart guide: http://www.mongodb.org/display/DOCS/CSharp+Driver+Quickstart Reference links C# Language Center: http://www.mongodb.org/display/DOCS/CSharp+Language+Center MongoDB Server Documentation: http://www.mongodb.org/display/DOCS/Home MongoDB Server Downloads: http://www.mongodb.org/downloads MongoDB client drivers download: http://www.mongodb.org/display/DOCS/Drivers MongoDB Community content: http://www.mongodb.org/display/DOCS/CSharp+Community+Projects Tutorials Tutorial MongoDB con ASP.NET MVC - Ejemplo Práctico (Spanish):http://geeks.ms/blogs/gperez/archive/2011/12/02/tutorial-mongodb-con-asp-net-mvc-ejemplo-pr-225-ctico.aspx MongoDB and C#:http://www.codeproject.com/Articles/87757/MongoDB-and-C C# driver LINQ tutorial:http://www.mongodb.org/display/DOCS/CSharp+Driver+LINQ+Tutorial C# driver reference: http://www.mongodb.org/display/DOCS/CSharp+Driver+Tutorial Safe Mode Connection The C# driver supports two connection modes: safe and unsafe. Safe connection mode (only applies to methods that modify data in a database like Inserts, Deletes and Updates. While the current driver defaults to unsafe mode (safeMode == false) it's recommended to always enable safe mode, and force unsafe mode on specific things we know aren't critical. When safe mode is enabled, the driver internal code calls the MongoDB "getLastError" function to ensure the last operation is completed before returning control the the caller. For more information on using safe mode and their implicancies on performance and data reliability see: http://www.mongodb.org/display/DOCS/getLastError+Command If safe mode is not enabled, all data modification calls to the database are executed asynchronously (fire & forget) without waiting for the result of the operation. This mode could be useful for creating / updating non-critical data like performance counters, usage logging and so on. It's important to know that not using safe mode implies that data loss can occur without any notification to the caller. As with any wait operation, enabling safe mode also implies dealing with timeouts. For more information about C# driver safe mode configuration see: http://www.mongodb.org/display/DOCS/CSharp+getLastError+and+SafeMode The safe mode configuration can be specified at different levels: Connection string: mongodb://hostname/?safe=true Database: when obtaining a database instance using the server.GetDatabase(name, safeMode) method Collection: when obtaining a collection instance using the database.GetCollection(name, safeMode) method Operation: for example, when executing the collection.Insert(document, safeMode) method Some useful SafeMode article: http://stackoverflow.com/questions/4604868/mongodb-c-sharp-safemode-official-driver Exception Handling The driver ensures that an exception will be thrown in case of something going wrong, in case of using safe mode (as said above, when not using safe mode no exception will be thrown no matter what the outcome of the operation is). As explained here https://groups.google.com/forum/?fromgroups#!topic/mongodb-user/mS6jIq5FUiM there is no need to check for any returned value from a driver method inserting data. With updates the situation is similar to any other relational database: if an update command doesn't affect any records, the call will suceed anyway (no exception thrown) and you manually have to check for something like "records affected". For MongoDB, an Update operation will return an instance of the "SafeModeResult" class, and you can verify the "DocumentsAffected" property to ensure the intended document was indeed updated. Note: Please remember that an Update method might return a null instance instead of an "SafeModeResult" instance when safe mode is not enabled. Useful Community Articles Comments about how MongoDB works and how that might affect your application: http://ethangunderson.com/blog/two-reasons-to-not-use-mongodb/ FourSquare using MongoDB had serious scalability problems: http://mashable.com/2010/10/07/mongodb-foursquare/ Is MongoDB a replacement for Memcached? http://www.quora.com/Is-MongoDB-a-good-replacement-for-Memcached/answer/Rick-Branson MongoDB Introduction, shell, when not to use, maintenance, upgrade, backups, memory, sharding, etc: http://www.markus-gattol.name/ws/mongodb.html MongoDB Collection level locking support: https://jira.mongodb.org/browse/SERVER-1240 MongoDB performance tips: http://www.quora.com/MongoDB/What-are-some-best-practices-for-optimal-performance-of-MongoDB-particularly-for-queries-that-involve-multiple-documents Lessons learned migrating from SQL Server to MongoDB: http://www.wireclub.com/development/TqnkQwQ8CxUYTVT90/read MongoDB replication performance: http://benshepheard.blogspot.com.ar/2011/01/mongodb-replication-performance.html

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• Code is not the best way to draw

  - by Bertrand Le Roy

  It should be quite obvious: drawing requires constant visual feedback. Why is it then that we still draw with code in so many situations? Of course it’s because the low-level APIs always come first, and design tools are built after and on top of those. Existing design tools also don’t typically include complex UI elements such as buttons. When we launched our Touch Display module for Netduino Go!, we naturally built APIs that made it easy to draw on the screen from code, but very soon, we felt the limitations and tedium of drawing in code. In particular, any modification requires a modification of the code, followed by compilation and deployment. When trying to set-up buttons at pixel precision, the process is not optimal. On the other hand, code is irreplaceable as a way to automate repetitive tasks. While tools like Illustrator have ways to repeat graphical elements, they do so in a way that is a little alien and counter-intuitive to my developer mind. From these reflections, I knew that I wanted a design tool that would be structurally code-centric but that would still enable immediate feedback and mouse adjustments. While thinking about the best way to achieve this goal, I saw this fantastic video by Bret Victor: The key to the magic in all these demos is permanent execution of the code being edited. Whenever a parameter is being modified, everything is re-executed immediately so that the impact of the modification is instantaneously visible. If you do this all the time, the code and the result of its execution fuse in the mind of the user into dual representations of a single object. All mental barriers disappear. It’s like magic. The tool I built, Nutshell, is just another implementation of this principle. It manipulates a list of graphical operations on the screen. Each operation has a nice editor, and translates into a bit of code. Any modification to the parameters of the operation will modify the bit of generated code and trigger a re-execution of the whole program. This happens so fast that it feels like the drawing reacts instantaneously to all changes. The order of the operations is also the order in which the code gets executed. So if you want to bring objects to the front, move them down in the list, and up if you want to move them to the back: But where it gets really fun is when you start applying code constructs such as loops to the design tool. The elements that you put inside of a loop can use the loop counter in expressions, enabling crazy scenarios while retaining the real-time edition features. When you’re done building, you can just deploy the code to the device and see it run in its native environment: This works thanks to two code generators. The first code generator is building JavaScript that is executed in the browser to build the canvas view in the web page hosting the tool. The second code generator is building the C# code that will run on the Netduino Go! microcontroller and that will drive the display module. The possibilities are fascinating, even if you don’t care about driving small touch screens from microcontrollers: it is now possible, within a reasonable budget, to build specialized design tools for very vertical applications. Direct feedback is a powerful ally in many domains. Code generation driven by visual designers has become more approachable than ever thanks to extraordinary JavaScript libraries and to the powerful development platform that modern browsers provide. I encourage you to tinker with Nutshell and let it open your eyes to new possibilities that you may not have considered before. It’s open source. And of course, my company, Nwazet, can help you develop your own custom browser-based direct feedback design tools. This is real visual programming…

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• Best Design Pattern for Coupling User Interface Components and Data Structures

  - by szahn

  I have a windows desktop application with a tree view. Due to lack of a sound data-binding solution for a tree view, I've implemented my own layer of abstraction on it to bind nodes to my own data structure. The requirements are as follows: Populate a tree view with nodes that resemble fields in a data structure. When a node is clicked, display the appropriate control to modify the value of that property in the instance of the data structure. The tree view is populated with instances of custom TreeNode classes that inherit from TreeNode. The responsibility of each custom TreeNode class is to (1) format the node text to represent the name and value of the associated field in my data structure, (2) return the control used to modify the property value, (3) get the value of the field in the control (3) set the field's value from the control. My custom TreeNode implementation has a property called "Control" which retrieves the proper custom control in the form of the base control. The control instance is stored in the custom node and instantiated upon first retrieval. So each, custom node has an associated custom control which extends a base abstract control class. Example TreeNode implementation: //The Tree Node Base Class public abstract class TreeViewNodeBase : TreeNode { public abstract CustomControlBase Control { get; } public TreeViewNodeBase(ExtractionField field) { UpdateControl(field); } public virtual void UpdateControl(ExtractionField field) { Control.UpdateControl(field); UpdateCaption(FormatValueForCaption()); } public virtual void SaveChanges(ExtractionField field) { Control.SaveChanges(field); UpdateCaption(FormatValueForCaption()); } public virtual string FormatValueForCaption() { return Control.FormatValueForCaption(); } public virtual void UpdateCaption(string newValue) { this.Text = Caption; this.LongText = newValue; } } //The tree node implementation class public class ExtractionTypeNode : TreeViewNodeBase { private CustomDropDownControl control; public override CustomControlBase Control { get { if (control == null) { control = new CustomDropDownControl(); control.label1.Text = Caption; control.comboBox1.Items.Clear(); control.comboBox1.Items.AddRange( Enum.GetNames( typeof(ExtractionField.ExtractionType))); } return control; } } public ExtractionTypeNode(ExtractionField field) : base(field) { } } //The custom control base class public abstract class CustomControlBase : UserControl { public abstract void UpdateControl(ExtractionField field); public abstract void SaveChanges(ExtractionField field); public abstract string FormatValueForCaption(); } //The custom control generic implementation (view) public partial class CustomDropDownControl : CustomControlBase { public CustomDropDownControl() { InitializeComponent(); } public override void UpdateControl(ExtractionField field) { //Nothing to do here } public override void SaveChanges(ExtractionField field) { //Nothing to do here } public override string FormatValueForCaption() { //Nothing to do here return string.Empty; } } //The custom control specific implementation public class FieldExtractionTypeControl : CustomDropDownControl { public override void UpdateControl(ExtractionField field) { comboBox1.SelectedIndex = comboBox1.FindStringExact(field.Extraction.ToString()); } public override void SaveChanges(ExtractionField field) { field.Extraction = (ExtractionField.ExtractionType) Enum.Parse(typeof(ExtractionField.ExtractionType), comboBox1.SelectedItem.ToString()); } public override string FormatValueForCaption() { return string.Empty; } The problem is that I have "generic" controls which inherit from CustomControlBase. These are just "views" with no logic. Then I have specific controls that inherit from the generic controls. I don't have any functions or business logic in the generic controls because the specific controls should govern how data is associated with the data structure. What is the best design pattern for this?

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• Best Practices - Core allocation

  - by jsavit

  This post is one of a series of "best practices" notes for Oracle VM Server for SPARC (also called Logical Domains) Introduction SPARC T-series servers currently have up to 4 CPU sockets, each of which has up to 8 or (on SPARC T3) 16 CPU cores, while each CPU core has 8 threads, for a maximum of 512 dispatchable CPUs. The defining feature of Oracle VM Server for SPARC is that each domain is assigned CPU threads or cores for its exclusive use. This avoids the overhead of software-based time-slicing and emulation (or binary rewriting) of system state-changing privileged instructions used in traditional hypervisors. To create a domain, administrators specify either the number of CPU threads or cores that the domain will own, as well as its memory and I/O resources. When CPU resources are assigned at the individual thread level, the logical domains constraint manager attempts to assign threads from the same cores to a domain, and avoid "split core" situations where the same CPU core is used by multiple domains. Sometimes this is unavoidable, especially when domains are allocated and deallocated CPUs in small increments. Why split cores can matter Split core allocations can silenty reduce performance because multiple domains with different address spaces and memory contents are sharing the core's Level 1 cache (L1$). This is called false cache sharing since even identical memory addresses from different domains must point to different locations in RAM. The effect of this is increased contention for the cache, and higher memory latency for each domain using that core. The degree of performance impact can be widely variable. For applications with very small memory working sets, and with I/O bound or low-CPU utilization workloads, it may not matter at all: all machines wait for work at the same speed. If the domains have substantial workloads, or are critical to performance then this can have an important impact: This blog entry was inspired by a customer issue in which one CPU core was split among 3 domains, one of which was the control and service domain. The reported problem was increased I/O latency in guest domains, but the root cause might be higher latency servicing the I/O requests due to the control domain being slowed down. What to do about it Split core situations are easily avoided. In most cases the logical domain constraint manager will avoid it without any administrative action, but it can be entirely prevented by doing one of the several actions: Assign virtual CPUs in multiples of 8 - the number of threads per core. For example: ldm set-vcpu 8 mydomain or ldm add-vcpu 24 mydomain. Each domain will then be allocated on a core boundary. Use the whole core constraint when assigning CPU resources. This allocates CPUs in increments of entire cores instead of virtual CPU threads. The equivalent of the above commands would be ldm set-core 1 mydomain or ldm add-core 3 mydomain. Older syntax does the same thing by adding the -c flag to the add-vcpu, rm-vcpu and set-vcpu commands, but the new syntax is recommended. When whole core allocation is used an attempt to add cores to a domain fails if there aren't enough completely empty cores to satisfy the request. See https://blogs.oracle.com/sharakan/entry/oracle_vm_server_for_sparc4 for an excellent article on this topic by Eric Sharakan. Don't obsess: - if the workloads have minimal CPU requirements and don't need anywhere near a full CPU core, then don't worry about it. If you have low utilization workloads being consolidated from older machines onto a current T-series, then there's no need to worry about this or to assign an entire core to domains that will never use that much capacity. In any case, make sure the most important domains have their own CPU cores, in particular the control domain and any I/O or service domain, and of course any important guests. Summary Split core CPU allocation to domains can potentially have an impact on performance, but the logical domains manager tends to prevent this situation, and it can be completely and simply avoided by allocating virtual CPUs on core boundaries.

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• Doubts about several best practices for rest api + service layer

  - by TheBeefMightBeTough

  I'm going to be starting a project soon that exposes a restful api for business intelligence. It may not be limited to a restful api, so I plan to delegate requests to a service layer that then coordinates multiple domain objects (each of which have business logic local to the object). The api will likely have many calls as it is a long-term project. While thinking about the design, I recalled a few best practices. 1) Use command objects at the controller layer (I'm using Spring MVC). 2) Use DTOs at the service layer. 3) Validate in both the controller and service layer, though for different reasons. I have my doubts about these recommendations. 1) Using command objects adds a lot of extra single-purpose classes (potentially one per request). What exactly is the benefit? Annotation based validation can be done using this approach, sure. What if I have two requests that take the same parameters, but have different validation requirements? I would have to have two different classes with exactly the same members but different annotations? Bleh. 2) I have heard that using DTOs is preferable to parameters because it makes for more maintainable code down the road (say, e.g., requirements change and the service parameters need to be altered). I don't quite understand this. Shouldn't an api be more-or-less set in stone? I would understand that in the early phases of a project (or, especially, an entire company) the domain itself will not be well understood, and thus core domain objects may change along with the apis that manipulate these objects. At this point however the number of api methods should be small and their dependents few, so changes to the methods could easily be tolerated from a maintainability standpoint. In a large api with many methods and a substantial domain model, I would think having a DTO for potentially each domain object would become unwieldy. Am I misunderstanding something here? 3) I see validation in the controller and service layer as redundant in most cases. Why would I validate that parameters are not null and are in general well formed in the controller if the service is going to do exactly the same (and more). Couldn't I just do all the validation in the service and throw a runtime exception with a list of bad parameters then catch that in the controller to make the error messages more presentable? Better yet, couldn't I just make the error messages user-friendly in the service and let the exception trickle up to a global handler (ControllerAdvice in spring, for example)? Is there something wrong with either of these approaches? (I do see a use case for controller validation if the input does not map one-to-one with the service input, but since the controllers are for a rest api and not forms, the api parameters will probably map directly to service parameters.) I do also have a question about unchecked vs checked exceptions. Namely, I'm not really sure why I'd ever want to use a checked exception. Every time I have seen them used they just get wrapped into general exceptions (DomainException, SystemException, ApplicationException, w/e) to reduce the signature length of methods, or devs catch Exception rather than dealing with the App1Exception, App2Exception, Sys1Exception, Sys2Exception. I don't see how either of these practices is very useful. Why not just use unchecked exceptions always and catch the ones you actually do care about? You could just document what unchecked exceptions the method throws.

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• Best approach to depth streaming via existing codec

  - by Kevin

  I'm working on a development system (and game) intended for games set mostly in static third-person views. We produce our scenery by CG and photographic techniques. Our background art is rendered off-line by a production-grade renderer. To allow the runtime imagery to properly interact with the background art, I wrote a program to convert from depth output by Mental Ray into a texture, and a pixel shader to draw a quad such that the Z data comes from the texture. This technique is working out very well, but now we've decided that some of the camera angle changes between scenes should be animated. The animation itself is straightforward to produce from our CG models. We intend to encode it to some HD video codec such as H.264. The problem is that in order to maintain our runtime imagery on the screen, the depth buffer will need to be loaded for each video frame. Due to the bandwidth, the video's depth data will need to be compressed efficiently. I've looked into methods for performing temporal compression of depth info and found an interesting research paper here: http://web4.cs.ucl.ac.uk/staff/j.kautz/publications/depth-streaming.pdf The method establishes a mapping between 16-bit depth values and YCbCr values. The mapping is tuned to the properties of existing video codecs in order to maximize precision of the decoded depths after the YCbCr has undergone video compression. It allows an existing, unmodified video codec to be used on the backend. I'm looking at how to pull this off with the least possible work. (This design change was unplanned.) Our game engine itself is native C++, presently for Win32 and DirectX, although we've worked hard to keep platform dependence segregated because we intend other ports. We don't have motion video facilities in the engine yet but will ultimately need that anyway for cinematics. I was planning on using some off-the-shelf motion video solution we can plug into our engine, and haven't chosen one yet. This new added requirement makes selecting one harder since, among other things, we'll now need to bypass colourspace conversion on one of the streams, and also will need to be playing two streams simultaneously in lockstep, on top of in some cases audio on one of them (for the cinematics). I'm also wondering if it's possible (or even useful) to do the conversion from YCbCr to depth in a pixel shader, or if it's better to just do it in CPU and separately load the resulting depth values into a locked tex. The conversion unfortunately does involve branching logic per-pixel. (There are more naive mappings that don't need branching, but they produce inferior results.) It could be reduced to a table lookup but the table would be 32MB. Programming is second-nature to me but I'm not that experienced with pix shaders and have zero knowledge of off-the-shelf video solutions. I'd therefore be interested in advice from others who may have dealt more with depth streaming, pixel shaders, and/or off-the-shelf codecs, regarding how feasible the proposed application is and what off-the-shelf video systems out there would best get along with this usage case.

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• I am trying to figure out the best way to understand how to cache domain objects

  - by Brett Ryan

  I've always done this wrong, I'm sure a lot of others have too, hold a reference via a map and write through to DB etc.. I need to do this right, and I just don't know how to go about it. I know how I want my objects to be cached but not sure on how to achieve it. What complicates things is that I need to do this for a legacy system where the DB can change without notice to my application. So in the context of a web application, let's say I have a WidgetService which has several methods: Widget getWidget(); Collection<Widget> getAllWidgets(); Collection<Widget> getWidgetsByCategory(String categoryCode); Collection<Widget> getWidgetsByContainer(Integer parentContainer); Collection<Widget> getWidgetsByStatus(String status); Given this, I could decide to cache by method signature, i.e. getWidgetsByCategory("AA") would have a single cache entry, or I could cache widgets individually, which would be difficult I believe; OR, a call to any method would then first cache ALL widgets with a call to getAllWidgets() but getAllWidgets() would produce caches that match all the keys for the other method invocations. For example, take the following untested theoretical code. Collection<Widget> getAllWidgets() { Entity entity = cache.get("ALL_WIDGETS"); Collection<Widget> res; if (entity == null) { res = loadCache(); } else { res = (Collection<Widget>) entity.getValue(); } return res } Collection<Widget> loadCache() { // Get widgets from underlying DB Collection<Widget> res = db.getAllWidgets(); cache.put("ALL_WIDGETS", res); Map<String, List<Widget>> byCat = new HashMap<>(); for (Widget w : res) { // cache by different types of method calls, i.e. by category if (!byCat.containsKey(widget.getCategory()) { byCat.put(widget.getCategory(), new ArrayList<Widget>); } byCat.get(widget.getCatgory(), widget); } cacheCategories(byCat); return res; } Collection<Widget> getWidgetsByCategory(String categoryCode) { CategoryCacheKey key = new CategoryCacheKey(categoryCode); Entity ent = cache.get(key); if (entity == null) { loadCache(); } ent = cache.get(key); return ent == null ? Collections.emptyList() : (Collection<Widget>)ent.getValue(); } NOTE: I have not worked with a cache manager, the above code illustrates cache as some object that may hold caches by key/value pairs, though it's not modelled on any specific implementation. Using this I have the benefit of being able to cache all objects in the different ways they will be called with only single objects on the heap, whereas if I were to cache the method call invocation via say Spring It would (I believe) cache multiple copies of the objects. I really wish to try and understand the best ways to cache domain objects before I go down the wrong path and make it harder for myself later. I have read the documentation on the Ehcache website and found various articles of interest, but nothing to give a good solid technique. Since I'm working with an ERP system, some DB calls are very complicated, not that the DB is slow, but the business representation of the domain objects makes it very clumsy, coupled with the fact that there are actually 11 different DB's where information can be contained that this application is consolidating in a single view, this makes caching quite important.

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• The best computer ever

  - by Jeff

  (This is a repost from my personal blog… wow… I need to write more technical stuff!) About three years and three months ago, I bought a 17" MacBook Pro, and it turned out to be the best computer I've ever owned. You might think that every computer with better specs is automatically better than the last, but that hasn't been my experience. My first one was a Sony, back in the Pentium III days, and it cost an astonishing $2,500. That was even more ridiculous in 1999 dollars. It had a dial-up modem, and a CD-ROM, built-in! It may have even played DVD's. A few years later I bought an HP, and it ended up being a pile of shit. The power connector inside came loose from the board, and on occasion would even short. In 2005, I bought a Dell, and it wasn't bad. It had a really high resolution screen (complete with dead pixels, a problem in those days), and it was the first laptop I felt I could do real work on. When 2006 rolled around, Apple started making computers with Intel CPU's, and I bought the very first one the week it came out. I used Boot Camp to run Windows. I still have it in its box somewhere, and I used it for three years. The current 17" was new in 2009. The goodness was largely rooted in having a big screen with lots of dots. This computer has been the source of hundreds of blog posts, tens of thousands of lines of code, video and photo editing, and of course, a whole lot of Web surfing. It connected to corpnet at Microsoft, WiFi in Hawaii and has presented many a deck. It has traveled with me tens of thousands of miles. Last year, I put a solid state drive in it, and it was like getting a new computer. I can boot up a Windows 7 VM in about 19 seconds. Having 8 gigs of RAM has always been fantastic. Everything about it has been fast and fun. When new, the battery (when not using VM's) could get as much as 10 hours. I can still do 7 without much trouble. After 460 charge cycles, the battery health is still between 85 and 90%. The only real negative has been the size and weight. It's only an inch thick, but naturally it's pretty big with a 17" screen. You don't get battery life like that without a huge battery, either, so it's heavy. It was never a deal breaker, but sometimes a long haul across a large airport, you know you're carrying it. Today, Apple announced a new, thinner and lighter 15" laptop, with twice the RAM and CPU cores, and four times the screen resolution. It basically handles my size and weight issues while retaining the resolution, and it still costs less than my 17" did. So I ordered one. Three years is an excellent run, but I kind of budgeted for a new workhorse this year anyway. So if you're interested in a 17" MacBook Pro with a Core 2 Duo 2.66 GHz CPU, 8 gigs of RAM and a 320 gig hard drive (sorry, I'm keeping the SSD), I have one to sell. They've apparently discontinued the 17", which is going to piss off the video community. It's in excellent condition, with a few minor scratches, but I take care of my stuff.

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• Best way to process a queue in C# (PDF treatment)

  - by Bartdude

  First of all let me expose what I would like to do : I already dispose of a long-time running webapp developed in ASP.NET (C#) 2.0. In this app, users can upload standard PDF files (text+pics). The app is running in production on a Windows Server 2003 and has a dedicated database server (SQL server 2008) also running Windows Server 2003. I myself am a quite experienced web developer, but never actually programmed anything non-web (or at least nothing serious). I plan on adding a functionality to the webapp for which I would need a jpg snapshot of each page of the PDF. Creating these "thumbnails" isn't the big deal as such, I already do it inside my webapp using ghostscript. I've only done it on 1 page documents for now though, and the new functionality will need to process bigger documents. In order for this process to be transparent aswell for the admins as the final users, I would like to implement some kind of queue to delay the processing of the thumbnails. There again, no problem to create the queue, it will consist of records in a table, with enough info to find the pdf document back. Then I will need to process this queue, and that's were my interrogations start. Obviously the best solution to process it isn't an ASP script or so, so I will have to get out of my known environment. No problem, but I have no idea which direction to go. Therefore, a few questions : What should I develop ? I presumably need something that is "standby" on the server, runs when needed, then returns to idle state until further notice.Should I be looking into Windows service ? Is there another more appropriate type of project ? Depending on the first answer, what will be the approach ? Should I have somehow SQL server "tell" the program/service/... to process the queue, or should I have that program/service/... periodically check the state of the queue and treat new items. In both case, which functionality can I use ? we're not talking about hundreds of PDF a day (max 50 maybe), I can totally afford to treat the queue 1 item at a time. Can you confirm I don't have to look much further on threads and so ? (I found a lot of answers talking about threads in queue treatment, but it looks quite overkill for my needs) Maybe linked to the previous question : what about concurrent call to the program, whatever it is ? Let's suppose it is currently running, and a new record comes in the queue, what should be the behaviour ? I don't need much detailed answers and would already be happy with answers like "You can do the processing with a service, and yes it's possible to have sqlserver on machine A trigger a service start on machine B" or "You have to develop xxx and then use the scheduler to run it every xxx minutes". I don't mind reading articles and so, but I can hardly afford to spend too much time learning stuff to finally realize I went the wrong way for this project, so basically I'm trying to narrow down the scope of matters I need to investigate. Thanks for reading me, I hope I'll find some helping hands on here :-)

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• Find the best OpenWorld sessions for learning about UX highlights

  - by mvaughan

  By Kathy Miedema, Oracle Applications User Experience  Have you clicked through the Oracle OpenWorld 2012 catalog? It’s amazingly dense, as usual. But one thing we noticed this year is that nearly half of the sessions mention some component of user experience, which is a sea change in our world. It means that more people understand, appreciate, and desire an effective user experience, and it also means that Oracle’s investment in its next-generation applications user experience, such as Oracle Fusion Applications, is increasingly apparent and interesting to its customers. So how do you choose the user experience sessions that make the most sense for you and your organization? Read our list to find out which sessions we think offer the most value for those interested in finding out more about the Oracle Applications user experience. If you’re interested in Oracle’s strategy for its user experience: CON9438: Oracle Fusion Applications: Transforming Insight into Action10:15 - 11:15 a.m. Tuesday, Oct. 2; Moscone West – 2007 CON9467: Oracle’s Roadmap to a Simple, Modern User Experience3:30 - 4:30 p.m. Wednesday, Oct. 3; Moscone West - 3002/3004 CON8718: Oracle Fusion Applications: Customizing and Extending with Oracle Composers11:15 a.m. - 12:15 p.m. Thursday, Oct. 4; Moscone West – 2008 GEN9663: General Session: A Panel of Masterminds—Where Are Oracle Applications Headed?1:45 - 2:45 p.m. Monday, Oct. 1; Moscone North - Hall D If you’re interested in PeopleSoft/PeopleTools: GEN8928: General Session: PeopleSoft Update and Product Roadmap3:15 - 4:15 p.m. Monday, Oct. 1; Moscone West - 3002/3004 CON9183: PeopleSoft PeopleTools Technology Roadmap4:45 - 5:45 p.m. Monday, Oct. 1; Moscone West - 3002/3004 CON8932: New Functional PeopleSoft PeopleTools Capabilities for the Line-of-Business User5:00 - 6:00 p.m. Tuesday, Oct. 2; Moscone West – 3007 If you’re interested in E-Business Suite: GEN8474: General Session: Oracle E-Business Suite—Strategy, Update, and Roadmap12:15 - 1:15 p.m. Monday, Oct. 1; Moscone West - 2002/2004 CON9026: Latest Oracle E-Business Suite 12.1 User Interface and Usability Enhancements1:15 - 2:15 p.m. Tuesday, Oct. 2; Moscone West – 2016 If you’re interested in Siebel: CON9700: Siebel CRM Overview, Strategy, and Roadmap12:15 - 1:15 p.m. Monday, Oct. 1; Moscone West – 2009 CON9703: User Interface Innovations with the New Siebel “Open UI”10:15 - 11:15 a.m. Tuesday, Oct. 2; Moscone West – 2009 If you’re interested in JD Edwards EnterpriseOne: HOL10452: JD Edwards EnterpriseOne 9.1 User Interface Changes10:15 - 11:15 a.m. Wednesday, Oct. 3; Marriott Marquis - Nob Hill AB CON9160: Showcase of the JD Edwards EnterpriseOne User Experience1:15 - 2:15 p.m. Wednesday, Oct. 3; InterContinental - Grand Ballroom B CON9159: Euphoria with the JD Edwards EnterpriseOne User Experience11:45 a.m. - 12:45 p.m. Wednesday, Oct. 3; InterContinental - Grand Ballroom B If you’re interested in Oracle Fusion Applications user experience design patterns: Functional design patterns that helped create the Oracle Fusion Applications user experience are now available. Learn more about these new, reusable usability solutions and best-practices at the Oracle JDeveloper and Oracle ADF demopods during Oracle OpenWorld 2012. Or visit the OTN Lounge between 4:30 p.m. and 6 p.m. on Wednesday, Oct. 3, to talk to Ultan O'Broin from the Oracle Applications User Experience team.    Demopod location: Moscone Center, South Exhibition Hall Level 1, S-207 OTN (Oracle Technology Network) Lounge: Howard Street tent On the demogrounds: Head to the demogrounds to see new demos from the Applications User Experience team, including the new look for Fusion Applications and what we’re building for mobile platforms. Take a spin on our eye tracker, a very cool tool that we use to research the usability of a particular design. Visit the Usable Apps OpenWorld page to find out where our demopods will be located.Photo by Martin Taylor, Oracle Applications User ExperienceA tour takes place in one of the usability labs at Oracle’s headquarters in Redwood Shores, Calif. At our labs, on-site and at HQ: We are also recruiting participants for our on-site lab, in which we gather feedback on new user experience designs, and taking reservations for a charter bus that will bring you to Oracle headquarters for a lab tour Thursday, Oct. 4, or Friday, Oct. 5. Tours leave at 10 a.m. and 1:45 p.m. from the Moscone Center in San Francisco. You’ll see more of our newest designs at the lab tour, and some of our research tools in action. For more information on any OpenWorld sessions, check the content catalog, also available at www.oracle.com/openworld. For information on Applications User Experience (Apps UX) sessions and activities, go to the Usable Apps OpenWorld page.

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• Availability Best Practices on Oracle VM Server for SPARC

  - by jsavit

  This is the first of a series of blog posts on configuring Oracle VM Server for SPARC (also called Logical Domains) for availability. This series will show how to how to plan for availability, improve serviceability, avoid single points of failure, and provide resiliency against hardware and software failures. Availability is a broad topic that has filled entire books, so these posts will focus on aspects specifically related to Oracle VM Server for SPARC. The goal is to improve Reliability, Availability and Serviceability (RAS): An article defining RAS can be found here. Oracle VM Server for SPARC Principles for Availability Let's state some guiding principles for availability that apply to Oracle VM Server for SPARC: Avoid Single Points Of Failure (SPOFs). Systems should be configured so a component failure does not result in a loss of application service. The general method to avoid SPOFs is to provide redundancy so service can continue without interruption if a component fails. For a critical application there may be multiple levels of redundancy so multiple failures can be tolerated. Oracle VM Server for SPARC makes it possible to configure systems that avoid SPOFs. Configure for availability at a level of resource and effort consistent with business needs. Effort and resource should be consistent with business requirements. Production has different availability requirements than test/development, so it's worth expending resources to provide higher availability. Even within the category of production there may be different levels of criticality, outage tolerances, recovery and repair time requirements. Keep in mind that a simple design may be more understandable and effective than a complex design that attempts to "do everything". Design for availability at the appropriate tier or level of the platform stack. Availability can be provided in the application, in the database, or in the virtualization, hardware and network layers they depend on - or using a combination of all of them. It may not be necessary to engineer resilient virtualization for stateless web applications applications where availability is provided by a network load balancer, or for enterprise applications like Oracle Real Application Clusters (RAC) and WebLogic that provide their own resiliency. It's (often) the same architecture whether virtual or not: For example, providing resiliency against a lost device path or failing disk media is done for the same reasons and may use the same design whether in a domain or not. It's (often) the same technique whether using domains or not: Many configuration steps are the same. For example, configuring IPMP or creating a redundant ZFS pool is pretty much the same within the guest whether you're in a guest domain or not. There are configuration steps and choices for provisioning the guest with the virtual network and disk devices, which we will discuss. Sometimes it is different using domains: There are new resources to configure. Most notable is the use of alternate service domains, which provides resiliency in case of a domain failure, and also permits improved serviceability via "rolling upgrades". This is an important differentiator between Oracle VM Server for SPARC and traditional virtual machine environments where all virtual I/O is provided by a monolithic infrastructure that itself is a SPOF. Alternate service domains are widely used to provide resiliency in production logical domains environments. Some things are done via logical domains commands, and some are done in the guest: For example, with Oracle VM Server for SPARC we provide multiple network connections to the guest, and then configure network resiliency in the guest via IP Multi Pathing (IPMP) - essentially the same as for non-virtual systems. On the other hand, we configure virtual disk availability in the virtualization layer, and the guest sees an already-resilient disk without being aware of the details. These blogs will discuss configuration details like this. Live migration is not "high availability" in the sense of "continuous availability": If the server is down, then you don't live migrate from it! (A cluster or VM restart elsewhere would be used). However, live migration can be part of the RAS (Reliability, Availability, Serviceability) picture by improving Serviceability - you can move running domains off of a box before planned service or maintenance. The blog Best Practices - Live Migration on Oracle VM Server for SPARC discusses this. Topics Here are some of the topics that will be covered: Network availability using IP Multipathing and aggregates Disk path availability using virtual disks defined with multipath groups ("mpgroup") Disk media resiliency configuring for redundant disks that can tolerate media loss Multiple service domains - this is probably the most significant item and the one most specific to Oracle VM Server for SPARC. It is very widely deployed in production environments as the means to provide network and disk availability, but it can be confusing. Subsequent articles will describe why and how to configure multiple service domains. Note, for the sake of precision: an I/O domain is any domain that has a physical I/O resource (such as a PCIe bus root complex). A service domain is a domain providing virtual device services to other domains; it is almost always an I/O domain too (so it can have something to serve). Resources Here are some important links; we'll be drawing on their content in the next several articles: Oracle VM Server for SPARC Documentation Maximizing Application Reliability and Availability with SPARC T5 Servers whitepaper by Gary Combs Maximizing Application Reliability and Availability with the SPARC M5-32 Server whitepaper by Gary Combs Summary Oracle VM Server for SPARC offers features that can be used to provide highly-available environments. This and the following blog entries will describe how to plan and deploy them.

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• Bad to be logged in as admin all the time?

  - by poke

  At the office where I work, three of the other members of the IT staff are logged into their computers all the time with accounts that are members of the domain administrators group. I have serious concerns about being logged in with admin rights (either local or for the domain). As such, for everyday computer use, I use an account that just has regular user privelages. I also have an different account that is part of the domain admins group. I use this account when I need to do something that requires elevated privilages on my computer, one of the servers, or on another user's computer. What is the best practice here? Should network admins be logged in with rights to the entire network all the time (or even their local computer for that matter)?

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• Turn off the Linux OOM killer by default?

  - by Peter Eisentraut

  The OOM killer on Linux wreaks havoc with various applications every so often, and it appears that not much is really done on the kernel development side to improve this. Would it not be better, as a best practice when setting up a new server, to reverse the default on the memory overcommitting, that is, turn it off (vm.overcommit_memory=2) unless you know you want it on for your particular use? And what would those use cases be where you know you want the overcommitting on? As a bonus, since the behavior in case of vm.overcommit_memory=2 depends on vm.overcommit_ratio and swap space, what would be a good rule of thumb for sizing the latter two so that this whole setup keeps working reasonably?

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• In Puppet, how would I secure a password variable (in this case a MySQL password)?

  - by Beaming Mel-Bin

  I am using Puppet to provision MySQL with a parameterised class: class mysql::server( $password ) { package { 'mysql-server': ensure => installed } package { 'mysql': ensure => installed } service { 'mysqld': enable => true, ensure => running, require => Package['mysql-server'], } exec { 'set-mysql-password': unless => "mysqladmin -uroot -p$password status", path => ['/bin', '/usr/bin'], command => "mysqladmin -uroot password $password", require => Service['mysqld'], } } How can I protect $password? Currently, I removed the default world readable permission from the node definition file and explicitly gave puppet read permission via ACL. I'm assuming others have come across a similar situation so perhaps there's a better practice.

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• NTFS Permission Structure to allow Traversal but no Modification except in Leaf Nodes?

  - by pepoluan

  Assume there's this folder structure: D:\ --+-- Acctg --+-- Payable | +-- Receivable | +-- Fin --+-- Inv | +-- Tax | +-- Treas | +-- Mrktg --+-- Ads +-- Promo Users are not allowed to change the structure, but they are free to create & delete files & folders in the leaf nodes (i.e., the rightmost folders). AGDLP principle said that I should assign permissions on the above folders to DL-Groups. Let's say I have a G-Group of users, G-Accounting-Payable, containing users that have access to the D:\Acctg\Payable folder. The way I see it, I have two strategies: - Strategy 1 Create three DL-Groups and assign them permissions: DL-D-Acctg_T -- allowed traversal of D:\Acctg folder DL-D-Acctg-Pay_LF -- allowed listing of D:\Acctg\Payable folder contents DL-D-Acctg-Pay__RW -- allowed full permissions to the contents of D:\Acctg\Payable folder Add G-Accounting-Payable as member to all the above DL-Groups - Strategy 2 Create just one DL-Group DL-D-Acctg-Pay__RW, and assign it the proper permissions for each level of the folder. Then, add G-Accounting-Payable as member to that DL-Group. - Which strategy is the Recommended Best Practice, and why?

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• Which iptables rule do you think is a 'must have'

  - by Saif Bechan

  I have some basic iptable rules set up now for my vps. Just block everything except some default ports, 80,21,22,443. I do get brute forced a lot. I have heard that iptables is very powerful but I have not seen many use cases. Can you give me an example of a(some) rule(s) you always use and give a small example why. I can not find a general best practice post here on SF, if there is any I would like the link. If this is a duplicate I am sorry and it can be closed.

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• Software RAID to hardware RAID, can it be done?

  - by gtaylor85

  Can it be done ... well. (For the record, I did not set this server up.) In my server there are 4 disks. 3 of them are in a software RAID5, and 1 has the OS installed. I want to buy a RAID controller, 4 new HDs and set up a hardware RAID5. If possible, I'd like to just image the current setup, and use it to build my new one. My questions are: Can I image a 3 disk RAID5 to 4 disk RAID5? Are there problems with this? What is considered best practice for your OS. To have it on a separate disk like it currently is, or to install it on the RAID5? Thank you. I can clarify anything. I'm not sure what other info might be pertinent.

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• Separate tables or single table with queries?

  - by Joe

  I'm making an employee information database. I need to handle separated employees. Should I a. set up a query with a macro to send separated employees to a separate table, or b. just add a flag to the single table denoting separation? I understand that it's best practice to take choice b, and the one reason I can think of for this is that any structural changes I make to the table later will have to be done in both places. But it also seems like setting up a flag forces me to filter out that flag for basically every useful query I'm going to make in the future.

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• Do you work in your server room?

  - by Gary Richardson

  I once had a job offer from a company that wanted my workstation to be in the AC controlled, noisy server room with no natural light. I'm not sure what their motivation was. Possibly it made sense to them for me to be close to the servers, or possibly they wanted to save the desk space for other employees. I turned down the job (for many reasons, including the working environment). Is this a common practice? Do you work in your LAN room? How do you cope?

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