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  • Load a MySQL innodb database into memory

    - by jack
    I have a MySQL innodb database at 1.9GB, showed by following command. SELECT table_schema "Data Base Name", -> sum( data_length + index_length ) / 1024 / -> 1024 "Data Base Size in MB", -> sum( data_free )/ 1024 / 1024 "Free Space in MB" -> FROM information_schema.TABLES -> GROUP BY table_schema ; +--------------------+----------------------+------------------+ | Data Base Name | Data Base Size in MB | Free Space in MB | +--------------------+----------------------+------------------+ | database_name | 1959.73437500 | 31080.00000000 | My questions are: Does it mean if I set the innodb_buffer_pool_size to 2GB or larger, the whole database can be loaded into memory so much fewer read from disk requests are needed? What does the free space of 31GB mean? If the maximum RAM can be allocated to innodb_buffer_pool_size is 1GB, is it possible to specify which tables to loaded into memory while keep others always read from disk? Thanks in advance.

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  • Is it a good idea to keep all the enums in one place?

    - by kzen
    When I'm building a class library I usually create a file Enums.cs to hold all the enums used in the assembly. Here is an example: namespace MyNamespace { public enum Colors { Red, Green, Blue } public enum Shapes { Circle, Square, Triangle } } This makes all my enums easy to find, well organized and easy to access in code. I'm wondering if there is any reason why this would not be such a good idea?

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  • Double pointer as Objective-C block parameter

    - by George WS
    Is it possible (and if so, safe) to create/use a block which takes a double pointer as an argument? For instance: - (void)methodWithBlock:(void (^)(NSError **error))block; Additional context, research, and questions: I'm using ARC. When I declare the method above and attempt to call it, XCode autocompletes my method invocation as follows: [self methodWithBlock:^(NSError *__autoreleasing *error) {}]; What does __autoreleasing mean here and why is it being added? I presume it has something to do with ARC. If this is possible and safe, can the pointer still be dereferenced in the block as it would be anywhere else? In general, what are the important differences between doing what I'm describing, and simply passing a double pointer as a method parameter (e.g. - (void)methodWithDoublePointer:(NSError **)error;)? What special considerations, if any, should be taken into account (again assuming this is possible at all)?

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  • Implicit and Explicit implementation of interface.

    - by Amby
    While working on a upgrade i happened to come across a code like this. interface ICustomization { IMMColumnsDefinition GetColumnsDefinition(); } class Customization : ICustomization { private readonly ColumnDefinition _columnDefinition; //More code here. public ColumnsDefinition GetColumnsDefinition() { return _columnDefinition; } ColumnsDefinition ICustomization.GetColumnsDefinition() //redundant { return GetColumnsDefinition(); } } My question is: Is there any need/use of 'explicit' implementation of interface in this piece of code? Will it create any problem if i remove the method (explicit implementation of interface) that i have marked "redundant" above? PS: I understand that explicit implementation of interface is very important, and it can be used when we need to give access to a method at interface level only, and to use two interface with same signature of method.

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  • Creating simple waveforms with CoreAudio

    - by Koning Baard
    I am new to CoreAudio, and I would like to output a simple sine wave and square wave with a given frequency and amplitude through the speakers using CA. I don't want to use sound files as I want to synthesize the sound. What do I need to do this? And can you give me an example or tutorial? Thanks.

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  • mysql: encrypting and decrypting data

    - by cbrulak
    Does mysql provide a mechanism for storing and retrieving encrypted data? I don't mean passwords, I mean real strings. I'd like to encrypt a string, store in mysql and then retrieve the decrypted string at a later date. So, I know there is the AES_Encrypt and decrypt functions. But they ask for a key. (which is fine) but I wondering if you call those functions and use your user password as the key. Or something else that is super-simple. Also, is there a simple wrapper for the AES_Encrypt & decrypt functions in Rails? Or do you need to build the query manually?

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  • Error Creating View From Importing MysqlDump

    - by Joshua
    I don't speak SQL... Please, anybody help me. What does this mean?: Error SQL query: /*!50001 CREATE ALGORITHM=UNDEFINED *//*!50001 VIEW `v_sr_videntity` AS select `t`.`c_id` AS `ID`,`User`.`c_id` AS `UserID`,`videntityfingerprint`.`ID` AS `VIdentityFingerPrintID`,`videntityfingerprint`.`FingerPrintID` AS `FingerPrintID`,`videntityfingerprint`.`FingerPrintFingerPrint` AS `FingerPrintFingerPrint` from ((`t_SR_u_Identity` `t` join `t_SR_u_User` `User` on((`User`.`c_r_Identity` = `t`.`c_id`))) join `vi_sr_videntity_0` `VIdentityFingerPrint` on((`videntityfingerprint`.`c_r_Identity` = `t`.`c_id`))) */; MySQL said: #1054 - Unknown column 'videntityfingerprint.ID' in 'field list' What does this mean? What is it expecting? How do I fix it? This file was created by mysqldump, so why are there errors when I import it?

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  • How can I update an expression in a Runt::Schedule object?

    - by Reid Beels
    Runt provides a Schedule class for managing collections of events, each represented by a temporal expression. The Schedule class provides an update method, cited in the release notes as "allowing clients to update existing expressions". The implementation of this method, however, simply calls a supplied block, providing the temporal expression for the specified event (as shown). # From lib/runt/schedule.rb:61 # # Call the supplied block/Proc with the currently configured # TemporalExpression associated with the supplied Event. # def update(event,&block) block.call(@elems[event]) end How is one expected to use this method to update an expression?

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  • How to set the Cell height as dynamically in iPhone?

    - by Pugal Devan
    Hi Friends, In my apps, i have created table view and displayed the images and the labels in the table view. I have downloaded the image and set the image height into the another class, so i have set the image height as delegate value. In my problem is, heightForRowAtIndexPath method is call very earlier and it never calls again. So how i set the cell height depends on the image height? - (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath { In Console: the height of the image is --------------------------0.000000 the height of the image is --------------------------0.000000 the height of the image is --------------------------0.000000 } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { In Console: the height of the image is --------------------------98.567039 the height of the image is --------------------------300.000000 the height of the image is --------------------------232.288406 } Is any possible to call the heightforRowAtIndexPath method inside the cellForRowAt method. Because i have set the cell frame size and height depends on the image height. So how can i set the cell height depends on the image height?, please guide me. Thanks!

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  • How to make safe cast using generics in C#?

    - by TN
    I want to implement a generic method on a generic class which would allow to cast safely, see example: public class Foo<T> : IEnumerable<T> { ... public IEnumerable<R> SafeCast<R>() where T : R { return this.Select(item => (R)item); } } However, the compiler tells me that Foo<T>.SafeCast<R>() does not define parameter 'T'. I understand this message that I cannot specify a constraint on T in the method since it is not defined in the method. But how can I specify an inverse constraint?

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  • Garbage collecting at ColdFusion CFC

    - by Sergii
    Hello. I have a CFC as singletone object in Application scope. One of the methods is used for massive data processing and periodically causes the "Java heap space" errors. EDIT All variables inside the method are VAR-scoped, so they should not be kept in the object scope when invokation ended. It can be a bit dumb question for Java people, but I'd like to know how Java garbage collector cleans up the CFC methods memory: only when whole request ends, or maybe right after each method/function invokation? Second option is interesting because it can allow me to split my large method into the few, as one of the possible optimizations.

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  • Are there any pitfalls to var something = something || {}

    - by puk
    I came across this answer where the poster suggested that the shorthand for if(typeof MyNamespace === 'undefined'){ var MyNamespace = {}; } is var MyNamespace = MyNamespace || {}; Would veteran programmers recommend the latter to simplify the code, or does it overly complicate things, like abusing ++ or -- in complex compound statements? EDIT The reason I asked is b/c a while back someone inspired me by pointing out that a lot of the people who think they are expert programmers make a lot of beginners mistakes. The case at the time was if (isReady){ //Do Something } And what he was saying is that a condition should mean something, isReady doesn't 'mean' anything, instead, we should use if (isReady === true){ //Do Something }

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  • Constructor in a Interface?

    - by Sebi
    I know its not possible to define a constructor in a interface. But im wondering why, because i think i could be very useful. So you could be sure that some fields in a class are defined for every implementaiton of this interface. For example consider the following message class: public class MyMessage { public MyMessage(String receiver) { this.receiver = receiver; } private String receiver; public void send() { //some implementation for sending the mssage to the receiver } } If a define a Interface for this class so that i can have more classes which implement the message interface, i can only define the send method and not the constructor. So how can i assure that every implementation of this class really has an receiver setted? If i use a method like setReceiver(String receiver) i can't be sure that this method is really called. In the constructor i could assure it.

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  • Javascript: addClassName if input is checked and removeClassName if it was un-checked

    - by BoDiE2003
    Im trying to select all the li tags of the document and check if it hasClassName('yes') so if it has, it will remove it. But im having a TypeError: Object [object HTMLLIElement], has no method 'hasClassName' error. This is the DOM method: document.observe("dom:loaded", function() { $(document.body).select('input').each(function(element) { element.observe('click', function() { init(); }); init(); }); }); The previous code will take the init fuction and check the if there are checked inputs and add them the 'yes' class name, but if I un-check those inputs, the class remains. This is the funcion that Im trying to do dynamic (add and remove class 'yes'); function init() { $(document.body).select('input').each(function(element) { if (element.checked) { element.up('li').addClassName('yes'); } if ($(document.body).select('li').hasClassName('yes')) { element.removeClassName('yes'); } }) } Can you help me solving the last part of this function, so the removeclassname method will work? Thank you

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  • Model Binding an IList of selected items only

    - by jeef3
    I have an action method setup: public ActionResult Delete(IList<Product> products) And a table of products in my view. I have got Model Binding working so that on submit I can populate the products list. But I would like to populate it with only the products that are selected via a checkbox. I think I could do it by changing the action method to this: public ActionResult Delete(IList<Product> products, IList<int> toDelete) And passing the list of check boxes to the toDelete but I would really like to avoid changing the method signature if possible. Is there a way to pass only the selected items? Or am I going to have to write a custom ModelBinder?

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  • Special Character Meanings Defined

    - by Noctis Skytower
    In Python's module named string, there is a line that says whitespace = ' \t\n\r\v\f'. ' ' is a space character. '\t' is a tab character. '\n' is a newline character. '\r' is a carriage-return character. '\v' maps to '\x0b' (11). What does it mean and how might it be typed on a keyboard (any OS)? '\f' maps to '\x0c' (12). What does it mean and how might it be typed on a keyboard (any OS)?

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  • Why would it be a bad idea to have database connection open between client requests?

    - by AspOnMyNet
    1) Book I’m reading argues that connections shouldn’t be opened between client requests, since they are a finite resource. I realize that max pool size can quickly be reached and thus any further attempts to open a connection will be queued until connection becomes available and for that reason it would be imperative that we release connection as soon as possible. But assuming all request will open connection to the same DB, then I’m not sure how having a connection open between two client requests would be any less efficient than having each request first acquiring a connection from connection pool and later returning that object to connection pool? 2) Book also recommends that when database code is encapsulated in a dedicated data access class, then method M opening a database connection should also close that connection. a) I assume one reason why M should also close it, is because if method M opening the connection doesn’t also close it, but instead this connection object is used inside several methods, then it’s more likely that a programmer will forget to close it. b) Are there any other reasons why a method opening the connection should also close it? thanx

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  • Ruby on Rails form_remote_tag missing template

    - by Donald Hughes
    I'm using form_remote_tag(:url => {:controller => "home", :action => "search"}, :update => "mydiv"). When I click submit on the form "mydiv" is populated with the error "Template is missing. Missing template home/search.erb in view path app/views". I've tried multiple render options in def search, but they all result in the same error. It looks like the search method is trying to use it's default render even though I'm specifying what I want. I've tried: render 'index' render :text => 'Return this from my method!' Is my url incorrect? Is it not submitting back to my home controller's search method?

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  • creating a Menu from SQLite values in Java

    - by shanahobo86
    I am trying to create a ListMenu using data from an SQLite database to define the name of each MenuItem. So in a class called menu.java I have defined the array String classes [] = {}; which should hold each menu item name. In a DBAdapter class I created a function so the user can insert info to a table (This all works fine btw). public long insertContact(String name, String code, String location, String comments, int days, int start, int end, String type) { ContentValues initialValues = new ContentValues(); initialValues.put(KEY_NAME, name); initialValues.put(KEY_CODE, code); initialValues.put(KEY_LOCATION, location); initialValues.put(KEY_COMMENTS, comments); initialValues.put(KEY_DAYS, days); initialValues.put(KEY_START, start); initialValues.put(KEY_END, end); initialValues.put(KEY_TYPE, type); return db.insert(DATABASE_TABLE, null, initialValues); } It would be the Strings inserted into KEY_NAME that I need to populate that String array with. Does anyone know if this is possible? Thanks so much for the help guys. If I implement that function by Sam/Mango the program crashes, am I using it incorrectly or is the error due to the unknown size of the array? DBAdapter db = new DBAdapter(this); String classes [] = db.getClasses(); edit: I should mention that if I manually define the array: String classes [] = {"test1", "test2", "test3", etc}; It works fine. The error is a NullPointerException Here's the logcat (sorry about the formatting). I hadn't initialized with db = helper.getReadableDatabase(); in the getClasses() function but unfortunately it didn't fix the problem. 11-11 22:53:39.117: D/dalvikvm(17856): Late-enabling CheckJNI 11-11 22:53:39.297: D/TextLayoutCache(17856): Using debug level: 0 - Debug Enabled: 0 11-11 22:53:39.337: D/libEGL(17856): loaded /system/lib/egl/libGLES_android.so 11-11 22:53:39.337: D/libEGL(17856): loaded /system/lib/egl/libEGL_adreno200.so 11-11 22:53:39.357: D/libEGL(17856): loaded /system/lib/egl/libGLESv1_CM_adreno200.so 11-11 22:53:39.357: D/libEGL(17856): loaded /system/lib/egl/libGLESv2_adreno200.so 11-11 22:53:39.387: I/Adreno200-EGLSUB(17856): <ConfigWindowMatch:2078>: Format RGBA_8888. 11-11 22:53:39.407: D/memalloc(17856): /dev/pmem: Mapped buffer base:0x5c66d000 size:36593664 offset:32825344 fd:65 11-11 22:53:39.417: E/(17856): Can't open file for reading 11-11 22:53:39.417: E/(17856): Can't open file for reading 11-11 22:53:39.417: D/OpenGLRenderer(17856): Enabling debug mode 0 11-11 22:53:39.477: D/memalloc(17856): /dev/pmem: Mapped buffer base:0x5ecd3000 size:40361984 offset:36593664 fd:68 11-11 22:53:40.507: D/memalloc(17856): /dev/pmem: Mapped buffer base:0x61451000 size:7254016 offset:3485696 fd:71 11-11 22:53:41.077: I/Adreno200-EGLSUB(17856): <ConfigWindowMatch:2078>: Format RGBA_8888. 11-11 22:53:41.077: D/memalloc(17856): /dev/pmem: Mapped buffer base:0x61c4c000 size:7725056 offset:7254016 fd:74 11-11 22:53:41.097: D/memalloc(17856): /dev/pmem: Mapped buffer base:0x623aa000 size:8196096 offset:7725056 fd:80 11-11 22:53:41.937: D/memalloc(17856): /dev/pmem: Mapped buffer base:0x62b7b000 size:8667136 offset:8196096 fd:83 11-11 22:53:41.977: D/memalloc(17856): /dev/pmem: Unmapping buffer base:0x61c4c000 size:7725056 offset:7254016 11-11 22:53:41.977: D/memalloc(17856): /dev/pmem: Unmapping buffer base:0x623aa000 size:8196096 offset:7725056 11-11 22:53:41.977: D/memalloc(17856): /dev/pmem: Unmapping buffer base:0x62b7b000 size:8667136 offset:8196096 11-11 22:53:42.167: I/Adreno200-EGLSUB(17856): <ConfigWindowMatch:2078>: Format RGBA_8888. 11-11 22:53:42.177: D/memalloc(17856): /dev/pmem: Mapped buffer base:0x61c5d000 size:17084416 offset:13316096 fd:74 11-11 22:53:42.317: D/memalloc(17856): /dev/pmem: Mapped buffer base:0x63853000 size:20852736 offset:17084416 fd:80 11-11 22:53:42.357: D/OpenGLRenderer(17856): Flushing caches (mode 0) 11-11 22:53:42.357: D/memalloc(17856): /dev/pmem: Unmapping buffer base:0x5c66d000 size:36593664 offset:32825344 11-11 22:53:42.357: D/memalloc(17856): /dev/pmem: Unmapping buffer base:0x5ecd3000 size:40361984 offset:36593664 11-11 22:53:42.367: D/memalloc(17856): /dev/pmem: Unmapping buffer base:0x61451000 size:7254016 offset:3485696 11-11 22:53:42.757: D/memalloc(17856): /dev/pmem: Mapped buffer base:0x5c56d000 size:24621056 offset:20852736 fd:65 11-11 22:53:44.247: D/AndroidRuntime(17856): Shutting down VM 11-11 22:53:44.247: W/dalvikvm(17856): threadid=1: thread exiting with uncaught exception (group=0x40ac3210) 11-11 22:53:44.257: E/AndroidRuntime(17856): FATAL EXCEPTION: main 11-11 22:53:44.257: E/AndroidRuntime(17856): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{niall.shannon.timetable/niall.shannon.timetable.menu}: java.lang.NullPointerException 11-11 22:53:44.257: E/AndroidRuntime(17856): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1891) 11-11 22:53:44.257: E/AndroidRuntime(17856): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1992) 11-11 22:53:44.257: E/AndroidRuntime(17856): at android.app.ActivityThread.access$600(ActivityThread.java:127) 11-11 22:53:44.257: E/AndroidRuntime(17856): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1158) 11-11 22:53:44.257: E/AndroidRuntime(17856): at android.os.Handler.dispatchMessage(Handler.java:99) 11-11 22:53:44.257: E/AndroidRuntime(17856): at android.os.Looper.loop(Looper.java:137) 11-11 22:53:44.257: E/AndroidRuntime(17856): at android.app.ActivityThread.main(ActivityThread.java:4441) 11-11 22:53:44.257: E/AndroidRuntime(17856): at java.lang.reflect.Method.invokeNative(Native Method) 11-11 22:53:44.257: E/AndroidRuntime(17856): at java.lang.reflect.Method.invoke(Method.java:511) 11-11 22:53:44.257: E/AndroidRuntime(17856): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:823) 11-11 22:53:44.257: E/AndroidRuntime(17856): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:590) 11-11 22:53:44.257: E/AndroidRuntime(17856): at dalvik.system.NativeStart.main(Native Method) 11-11 22:53:44.257: E/AndroidRuntime(17856): Caused by: java.lang.NullPointerException 11-11 22:53:44.257: E/AndroidRuntime(17856): at android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:221) 11-11 22:53:44.257: E/AndroidRuntime(17856): at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:157) 11-11 22:53:44.257: E/AndroidRuntime(17856): at niall.shannon.timetable.DBAdapter.getClasses(DBAdapter.java:151) 11-11 22:53:44.257: E/AndroidRuntime(17856): at niall.shannon.timetable.menu.<init>(menu.java:15) 11-11 22:53:44.257: E/AndroidRuntime(17856): at java.lang.Class.newInstanceImpl(Native Method) 11-11 22:53:44.257: E/AndroidRuntime(17856): at java.lang.Class.newInstance(Class.java:1319) 11-11 22:53:44.257: E/AndroidRuntime(17856): at android.app.Instrumentation.newActivity(Instrumentation.java:1023) 11-11 22:53:44.257: E/AndroidRuntime(17856): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1882) 11-11 22:53:44.257: E/AndroidRuntime(17856): ... 11 more 11-11 22:53:46.527: I/Process(17856): Sending signal. PID: 17856 SIG: 9

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  • Have problem understanding the id/name of java bean

    - by symfony
    In an XmlBeanFactory (including ApplicationContext variants), you use the id or name attributes to specify the bean id(s), and at least one id must be specified in one or both of these attributes. Does it mean the following are legal? <bean id="test"> <bean name="test"> But this is illegal: <bean non_idnorname="test"> you may also or instead specify one or more bean ids (separated by a comma (,) or semicolon (;) via the name attribute. Does it mean I can specify multiple ids this way: <bean name="id1;id2,id3"> Can someone convince my doubt?

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