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• Are there any frameworks for data subscription and update?

  - by Timothy Pratley

  There is one server with multiple clients. The clients are viewing subsets of the servers entire data. If the data that a client is viewing changes, the client should be informed of the changes so that it displays the current data. Example: Two clients are viewing a list of users in an administration screen. One client adds a new user to the list and modifies the permissions of another user. The other client sees the changes propagated to their view.

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• Issue changing innodb_log_file_size

  - by savageguy

  I haven't done much tweaking in the past so this might be relatively easy however I am running into issues. This is what I do: Stop MySQL Edit my.cnf (changing innodb_log_file_size) Remove ib_logfile0/1 Start MySQL Starts fine however all InnoDB tables have the .frm file is invalid error, the status shows InnoDB engine is disabled so I obviously go back, remove the change and everything works again. I was able to change every other variable I've tried but I can't seem to find out why InnoDB fails to start even after removing the log files. Am I missing something? Thanks. Edit: Pasting of the log below - looks like it still seems to find the log file even though they are not there? Shutdown: 090813 10:00:14 InnoDB: Starting shutdown... 090813 10:00:17 InnoDB: Shutdown completed; log sequence number 0 739268981 090813 10:00:17 [Note] /usr/sbin/mysqld: Shutdown complete Startup after making the changes: InnoDB: Error: log file ./ib_logfile0 is of different size 0 5242880 bytes InnoDB: than specified in the .cnf file 0 268435456 bytes! 090813 11:00:18 [Warning] 'user' entry '[email protected]' ignored in --skip-name-resolve mode. 090813 11:00:18 [Note] /usr/sbin/mysqld: ready for connections. Version: '5.0.81-community-log' socket: '/var/lib/mysql/mysql.sock' port: 3306 MySQL Community Edition (GPL) 090813 11:00:19 [ERROR] /usr/sbin/mysqld: Incorrect information in file: './XXXX/User.frm' 090813 11:00:19 [ERROR] /usr/sbin/mysqld: Incorrect information in file: './XXXX/User.frm' 090813 11:00:19 [ERROR] /usr/sbin/mysqld: Incorrect information in file: './XXXX/User.frm' Its just a spam of the same error until I correct it When it did start after it recreated the log files so it must be looking in the same spot I am.

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• Is there an difference between transient properties defined in the data model, or in the custom subc

  - by mystify

  I was reading that setting the value of a transient property always results in marking the managed object as "dirty". However, what I don't get is this: If I make a subclass of NSManagedObject and use some extra properties which I don't need to be persistet, how does Core Data know about them and how can it mark the object as dirty when I access these? Again, they're not defined in the data model, so Core Data has no really good hint that they are there. Or does Core Data use some kind of introspection to analyze my custom class and figure out what properties I have in there?

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• Database design advice needed.

  - by user346271

  Hi all, I'm a lone developer for a telecoms company, and am after some database design advice from anyone with a bit of time to answer. I am inserting into one table ~2 million rows each day, these tables then get archived and compressed on a monthly basis. Each monthly table contains ~15,000,000 rows. Although this is increasing month on month. For every insert I do above I am combining the data from rows which belong together and creating another "correlated" table. This table is currently not being archived, as I need to make sure I never miss an update to the correlated table. (Hope that makes sense) Although in general this information should remain fairly static after a couple of days of processing. All of the above is working perfectly. However my company now wishes to perform some stats against this data, and these tables are getting too large to provide the results in what would be deemed a reasonable time. Even with the appropriate indexes set. So I guess after all the above my question is quite simple. Should I write a script which groups the data from my correlated table into smaller tables. Or should I store the queries result sets in something like memcache? I'm already using mysqls cache, but due to having limited control over how long the data is stored for, it's not working ideally. The main advantages I can see of using something like memcache: No blocking on my correlated table after the query has been cashed. Greater flexibility of sharing the collected data between the backend collector and front end processor. (i.e custom reports could be written in the backend and the results of these stored in the cache under a key which then gets shared with anyone who would want to see the data of this report) Redundancy and scalability if we start sharing this data with a large amount of customers. The main disadvantages I can see of using something like memcache: Data is not persistent if machine is rebooted / cache is flushed. The main advantages of using MySql Persistent data. Less code changes (although adding something like memcache is trivial anyway) The main disadvantages of using MySql Have to define table templates every time I want to store provide a new set of grouped data. Have to write a program which loops through the correlated data and fills these new tables. Potentially will still grow slower as the data continues to be filled. Apologies for quite a long question. It's helped me to write down these thoughts here anyway, and any advice/help/experience with dealing with this sort of problem would be greatly appreciated. Many thanks. Alan

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• Mass data store with SQL SERVER

  - by Leo

  We need management 10,000 GPS devices, each GPS device upload a GPS data every 30 seconds, these data need to store in the database(MS SQL Server 2005). Each GPS device daily data quantity is: 24 * 60 * 2 = 2,880 10 000 10,000 GPS devices daily data quantity is: 10000 * 2880 = 28,800,000 Each GPS data approximately 160Byte, the amount of data per day is: 28,800,000 * 160 = 4.29GB We need hold at least 3 months of GPS data in the database, My question is: 1, whether SQL Server 2005 can support such a large amount of data store? 2, How to plan data table? (all GPS data storage in one table? Daily table? Each GPS device with a GPS data table?) The GPS data: GPSID varchar(21), RecvTime datetime, GPSTime datetime, IsValid bit, IsNavi bit, Lng float, Lat float, Alt float, Spd smallint, Head smallint, PulseValue bigint, Oil float, TSW1 bigint, TSW1Mask bigint, TSW2 bigint, TSW2Mask, BSW bigint, StateText varchar(200), PosText varchar(200), UploadType tinyint

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• What are the different methods to expedite the data retrieval from database?

  - by saillu2003

  How can we expedite the data retrieval from the database for my web site which is extensively updating and fetching data from database.

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• C# or windows equivalent of OS X's Core Data?

  - by Nektarios

  I'm late to the boat and have only just now started using Core Data in OS X / Cocoa - it's incredible and is really changing the way I look at things. Is there an equivalent technology in C# or the modern Windows frameworks? i.e. having managed data types where you get saving, data management, deleting, searching all for free? Also wondering if there's anything like this on Linux.

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• What is the most efficient way to use Core Data?

  - by Eric

  I'm developing an iPad application using Core Data, and was hoping someone could clarify something about Core Data. Right now, I populate my table by making a fetch request for all of my data in viewDidLoad. I'd rather make individual fetch requests in my tableView:cellForRowAtIndexPath:. Can anyone tell me which is more efficient, and why? In other words, is it much less efficient to make lots of small requests as opposed to one big request?

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• Send multi message using jquery plugin in multi-row data?

  - by Agus Puryanto

  i use jquery.form to send a form, but in may case below how use this jquery plugin $('#htmlForm').ajaxForm({ target: '#htmlExampleTarget', success: function() { $('#htmlExampleTarget').fadeIn('slow'); $('#htmlForm').hide(); } }); for($i=1;$i<= 10;$i++){ //form $1 form name="form$i" action="blabla.php" input type="text" name="name$i" / input type="text" name="name$i" / input type="submit" name="submit" / }

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• R: How to write out a data.frame so that I can paste it into SO for others to read?

  - by John

  I have a large data.frame displaying some weird properties when plotted. I'd like to ask a question about it on Stackoverflow, to do that I'd like to write the data.frame out in a form that I can paste it into SO and somebody else can easily run it and have it back into a data.frame object again. Is there an easy way to accomplish this? Also, if it is really long, should I use paste bin instead of directly paste it here?

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• What happens if a user jumps over 10 versions before updating, and every version had a new data mode

  - by dontWatchMyProfile

  Example: User installs app v.1.0, adds data. Then the dev submits 10 updates in 10 weeks. After 11 weeks, the user wants v.11.0 and grabs a copy from the app store. Assuming that the app has got 11 .xcdatamodel versions inside, where ***11.xcdatamodel is the current one, what would happen now since the persistent store of the user is ages old? would the migration happen 10 times, step-by-step through every migration iteration? Or does the actual migration of data (lets assume gigabytes of data) happen exactly once, after Core Data (or the persistent store coordinator) has figured out precisely what to do to go from v.1.0 to v.11.0?

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• PHP PDO - bindValue PARAM_BOOL as string

  - by PHP_guy

  I'm freaking out here and can't figure out what's wrong. I'm pretty new to PDO, but everything works in my code except for booleans which are sent as strings. My code (simplified): $sql = 'SELECT * FROM pages WHERE clean_url_slo = :clean_url_slo AND published = :published LIMIT 1'; $clean_url_slo = 'home'; $published = true; Then I prepare stuff and execute it like this (simplified): $stmt = $db->prepare($sql); $stmt->bindValue(':clean_url_slo',$clean_url_slo,PDO::PARAM_STR); $stmt->bindValue(':published',$published,PDO::PARAM_BOOL); $stmt->execute(); And then here is what comes to mysql (from the mysql log - the query mysql received): 91 Query SELECT * FROM pages WHERE 1=1 AND clean_url_slo='domov' AND published='1' ORDER BY id desc LIMIT 1 As you can see, published is an integer - so always true, which is not OK. Why is that if I'm declaring it as a boolean? using: WAMP SERVER PHP version: 5.3.9 Mysql: 5.5.20 Many thanks for your help..

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• it is possible to "group by" without losing the original rows?

  - by toPeerOrNotToPeer

  i have a query like this: ID | name | commentsCount 1 | mysql for dummies | 33 2 | mysql beginners guide | 22 SELECT ..., commentsCount // will return 33 for first row, 22 for second one FROM mycontents WHERE name LIKE "%mysql%" also i want to know the total of comments, of all rows: SELECT ..., SUM(commentsCount) AS commentsCountAggregate // should return 55 FROM mycontents WHERE name LIKE "%mysql%" but this one obviously returns a single row with the total. now i want to merge these two queries in one single only, because my actual query is very heavy to execute (it uses boolean full text search, substring offset search, and sadly lot more), then i don't want to execute it twice is there a way to get the total of comments without making the SELECT twice? !! custom functions are welcome !! also variable usage is welcome, i never used them...

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• Using MCPKit framework in Cocoa app.

  - by pawz

  I'm trying to integrate the MCPKit MySQL framework available at http://mysql-cocoa.sourceforge.net/ into my cocoa application. I've added the framework and included the header file but when I try to define my first MCPConnection variable it says "MCPConnection undeclared". Is anyone successfully using MCPKit on leopard ? Or is there another framework that people use to access MySQL ?

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• In SQL, why is "select *, count(*) from sentGifts group by whenSent;" ok, but when "*" and "count(*)

  - by Jian Lin

  In SQL, using the table: mysql> select * from sentGifts; +--------+------------+--------+------+---------------------+--------+ | sentID | whenSent | fromID | toID | trytryWhen | giftID | +--------+------------+--------+------+---------------------+--------+ | 1 | 2010-04-24 | 123 | 456 | 2010-04-24 01:52:20 | 100 | | 2 | 2010-04-24 | 123 | 4568 | 2010-04-24 01:56:04 | 100 | | 3 | 2010-04-24 | 123 | NULL | NULL | 1 | | 4 | 2010-04-24 | NULL | 111 | 2010-04-24 03:10:42 | 2 | | 5 | 2010-03-03 | 11 | 22 | 2010-03-03 00:00:00 | 6 | | 6 | 2010-04-24 | 11 | 222 | 2010-04-24 03:54:49 | 6 | | 7 | 2010-04-24 | 1 | 2 | 2010-04-24 03:58:45 | 6 | +--------+------------+--------+------+---------------------+--------+ 7 rows in set (0.00 sec) The following is OK: mysql> select *, count(*) from sentGifts group by whenSent; +--------+------------+--------+------+---------------------+--------+----------+ | sentID | whenSent | fromID | toID | trytryWhen | giftID | count(*) | +--------+------------+--------+------+---------------------+--------+----------+ | 5 | 2010-03-03 | 11 | 22 | 2010-03-03 00:00:00 | 6 | 1 | | 1 | 2010-04-24 | 123 | 456 | 2010-04-24 01:52:20 | 100 | 6 | +--------+------------+--------+------+---------------------+--------+----------+ 2 rows in set (0.00 sec) But suppose we want the count(*) to appear as the first column: mysql> select count(*), * from sentGifts group by whenSent; ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '* from sentGifts group by whenSent' at line 1 it gave an error. Why is it so and what is a way to fix it? I realized that this is ok: mysql> select count(*), whenSent from sentGifts group by whenSent; +----------+------------+ | count(*) | whenSent | +----------+------------+ | 1 | 2010-03-03 | | 6 | 2010-04-24 | +----------+------------+ 2 rows in set (0.00 sec) but what about the one above that gave an error? thanks.

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• Can we use a sql data field as column name instead?

  - by Starx

  First a query SELECT * FROM mytable WHERE id='1' Gives me a certain number of rows For example id | context | cat | value 1 Context 1 1 value 1 1 Context 2 1 value 2 1 Context 1 2 value 3 1 Context 2 2 value 4 Now my problem instead of receiving the result in such way I want it is this way instead id | cat | Context 1 | Context 2 1 1 value 1 value 2 1 2 value 3 value 4

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• Apache crashes after installing mysqli

  - by Marco P.

  System: Apache 2.2 running on Windows 2008 Server with PHP 5.2.17 VC6 Thread-Safe as a Module and MySQL 5.5.17 - all working fine. After installing mysqli using the php package, Apache won't start anymore. There is no error message in the log. What I have tried: Make sure Windows PATH points to libmysql.dll: Yes, done. Make sure extension_dir points to the right point: Yes. Other extensions load fine. Try without mysqli: Yes, Apache loads fine then. Try without mysql: Yes, does not help. Test mysql itself: Restarts server! Overwrite libmysql: Yes, does not help. It seems to me that there is some general problem with MySql, but the DB server seems to be running fine. I'm really out of ideas of things I could try, so I'm desperate for any hints or tricks.

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• Iterating over a large data set in long running Python process - memory issues?

  - by user1094786

  I am working on a long running Python program (a part of it is a Flask API, and the other realtime data fetcher). Both my long running processes iterate, quite often (the API one might even do so hundreds of times a second) over large data sets (second by second observations of certain economic series, for example 1-5MB worth of data or even more). They also interpolate, compare and do calculations between series etc. What techniques, for the sake of keeping my processes alive, can I practice when iterating / passing as parameters / processing these large data sets? For instance, should I use the gc module and collect manually? Any advice would be appreciated. Thanks!

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• How do I add an index to a column that is datetime?

  - by alex

  In mysql. It's a date column

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• Storing large json strings to database + hash

  - by Guy

  I need to store quiete large JSON data strings to the database. I am using gzip to compress the string and therefore BLOB MySQL data type to store it. However, only 5% of all the requests contain unique data and only unique data ought to be stored to the database. My approach is as follows. array_multisort data (array [a, b, c] is virtually the same as [a, c, b]). json_encode data (json_encode is faster than serialize; we need string array representation for the step 3). sha1 data (slower than md5, though less possible the collisions). Check if the hash exists in the database. 5.1 yes – do not insert the data. 5.2. no – gzip the data and store it along the hash. Is there anything about this (apart from storing JSON data to the database in the first place) that sounds fishy or should be done a different way? p.s. We are talking about a database with roughly 1kk unique records being created every month.

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• ID cannot be null (Auto Increment)

  - by THeK

  I'm using an INSERT ON DUPLICATE KEY statement for my website. It's for creating news items, so I figured I could use the same MySQL command for both creating and updating news items. However, when I use the following: INSERT INTO table (id,title,content) VALUES(NULL,"Test","Test"); Instead of creating a new auto increment value it throws an error. However, the command works on my main development server. But not on my laptop. Both versions of MySQL are the same, the only difference being MySQL was installed manually on my server, and with WAMP on my laptop. Are there any MySQL Variables that could be causing this?

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• Split SQL statements

  - by eaZy

  Hello, I am writing a backend application which needs to be able to send multiple SQL commands to a MySQL server. MySQL = 5.x support multiple statements, but unfortunately we are interfacing with MySQL 4.x. I am trying to find a way (hint: regex) to split SQL statements by their semicolon, but it should ignore semicolons in single and double quotes strings. http://www.dev-explorer.com/articles/multiple-mysql-queries has a very nice regex to do that, but doesn't support double quotes. I'd be happy to hear your suggestions.

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• Opening the Table from the Database

  - by Gopal

  Am new to MySQL 5.1 In MySQL Where i can i find the Database & Table.... I was attached one database in MYSQL through odbc connectivity, How can i get that table values from the attached database. And also i want to create a table from the database..

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• WCF – interchangeable data-contract types

  - by nmarun

  In a WSDL based environment, unlike a CLR-world, we pass around the ‘state’ of an object and not the reference of an object. Well firstly, what does ‘state’ mean and does this also mean that we can send a struct where a class is expected (or vice-versa) as long as their ‘state’ is one and the same? Let’s see. So I have an operation contract defined as below: 1: [ServiceContract] 2: public interface ILearnWcfServiceExtend : ILearnWcfService 3: { 4: [OperationContract] 5: Employee SaveEmployee(Employee employee); 6: } 7:  8: [ServiceBehavior] 9: public class LearnWcfService : ILearnWcfServiceExtend 10: { 11: public Employee SaveEmployee(Employee employee) 12: { 13: employee.EmployeeId = 123; 14: return employee; 15: } 16: } Quite simplistic operation there (which translates to ‘absolutely no business value’). Now, the data contract Employee mentioned above is a struct. 1: public struct Employee 2: { 3: public int EmployeeId { get; set; } 4:  5: public string FName { get; set; } 6: } After compilation and consumption of this service, my proxy (in the Reference.cs file) looks like below (I’ve ignored the rest of the details just to avoid unwanted confusion): 1: public partial struct Employee : System.Runtime.Serialization.IExtensibleDataObject, System.ComponentModel.INotifyPropertyChanged I call the service with the code below: 1: private static void CallWcfService() 2: { 3: Employee employee = new Employee { FName = "A" }; 4: Console.WriteLine("IsValueType: {0}", employee.GetType().IsValueType); 5: Console.WriteLine("IsClass: {0}", employee.GetType().IsClass); 6: Console.WriteLine("Before calling the service: {0} - {1}", employee.EmployeeId, employee.FName); 7: employee = LearnWcfServiceClient.SaveEmployee(employee); 8: Console.WriteLine("Return from the service: {0} - {1}", employee.EmployeeId, employee.FName); 9: } The output is: I now change my Employee type from a struct to a class in the proxy class and run the application: 1: public partial class Employee : System.Runtime.Serialization.IExtensibleDataObject, System.ComponentModel.INotifyPropertyChanged { The output this time is: The state of an object implies towards its composition, the properties and the values of these properties and not based on whether it is a reference type (class) or a value type (struct). And as shown above, we’re actually passing an object by its state and not by reference. Continuing on the same topic of ‘type-interchangeability’, WCF treats two data contracts as equivalent if they have the same ‘wire-representation’. We can do so using the DataContract and DataMember attributes’ Name property. 1: [DataContract] 2: public struct Person 3: { 4: [DataMember] 5: public int Id { get; set; } 6:  7: [DataMember] 8: public string FirstName { get; set; } 9: } 10:  11: [DataContract(Name="Person")] 12: public class Employee 13: { 14: [DataMember(Name = "Id")] 15: public int EmployeeId { get; set; } 16:  17: [DataMember(Name="FirstName")] 18: public string FName { get; set; } 19: } I’ve created two data contracts with the exact same wire-representation. Just remember that the names and the types of data members need to match to be considered equivalent. The question then arises as to what gets generated in the proxy class. Despite us declaring two data contracts (Person and Employee), only one gets emitted – Person. This is because we’re saying that the Employee type has the same wire-representation as the Person type. Also that the signature of the SaveEmployee operation gets changed on the proxy side: 1: [System.CodeDom.Compiler.GeneratedCodeAttribute("System.ServiceModel", "4.0.0.0")] 2: [System.ServiceModel.ServiceContractAttribute(ConfigurationName="ServiceProxy.ILearnWcfServiceExtend")] 3: public interface ILearnWcfServiceExtend 4: { 5: [System.ServiceModel.OperationContractAttribute(Action="http://tempuri.org/ILearnWcfServiceExtend/SaveEmployee", ReplyAction="http://tempuri.org/ILearnWcfServiceExtend/SaveEmployeeResponse")] 6: ClientApplication.ServiceProxy.Person SaveEmployee(ClientApplication.ServiceProxy.Person employee); 7: } But, on the service side, the SaveEmployee still accepts and returns an Employee data contract. 1: [ServiceBehavior] 2: public class LearnWcfService : ILearnWcfServiceExtend 3: { 4: public Employee SaveEmployee(Employee employee) 5: { 6: employee.EmployeeId = 123; 7: return employee; 8: } 9: } Despite all these changes, our output remains the same as the last one: This is type-interchangeability at work! Here’s one more thing to ponder about. Our Person type is a struct and Employee type is a class. Then how is it that the Person type got emitted as a ‘class’ in the proxy? It’s worth mentioning that WSDL describes a type called Employee and does not say whether it is a class or a struct (see the SOAP message below): 1: <soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" 2: xmlns:tem="http://tempuri.org/" 3: xmlns:ser="http://schemas.datacontract.org/2004/07/ServiceApplication"> 4: <soapenv:Header/> 5: <soapenv:Body> 6: <tem:SaveEmployee> 7: <!--Optional:--> 8: <tem:employee> 9: <!--Optional:--> 10: <ser:EmployeeId>?</ser:EmployeeId> 11: <!--Optional:--> 12: <ser:FName>?</ser:FName> 13: </tem:employee> 14: </tem:SaveEmployee> 15: </soapenv:Body> 16: </soapenv:Envelope> There are some differences between how ‘Add Service Reference’ and the svcutil.exe generate the proxy class, but turns out both do some kind of reflection and determine the type of the data contract and emit the code accordingly. So since the Employee type is a class, the proxy ‘Person’ type gets generated as a class. In fact, reflecting on svcutil.exe application, you’ll see that there are a couple of places wherein a flag actually determines a type as a class or a struct. One example is in the ExportISerializableDataContract method in the System.Runtime.Serialization.CodeExporter class. Seems like these flags have a say in deciding whether the type gets emitted as a struct or a class. This behavior is different if you use the WSDL tool though. WSDL tool does not do any kind of reflection of the data contract / serialized type, it emits the type as a class by default. You can check this using the two command lines below:   Note to self: Remember ‘state’ and type-interchangeability when traversing through the WSDL planet!

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• Data management in unexpected places

  - by Ashok_Ora

  Normal 0 false false false EN-US X-NONE X-NONE Data management in unexpected places When you think of network switches, routers, firewall appliances, etc., it may not be obvious that at the heart of these kinds of solutions is an engine that can manage huge amounts of data at very high throughput with low latencies and high availability. Consider a network router that is processing tens (or hundreds) of thousands of network packets per second. So what really happens inside a router? Packets are streaming in at the rate of tens of thousands per second. Each packet has multiple attributes, for example, a destination, associated SLAs etc. For each packet, the router has to determine the address of the next “hop” to the destination; it has to determine how to prioritize this packet. If it’s a high priority packet, then it has to be sent on its way before lower priority packets. As a consequence of prioritizing high priority packets, lower priority data packets may need to be temporarily stored (held back), but addressed fairly. If there are security or privacy requirements associated with the data packet, those have to be enforced. You probably need to keep track of statistics related to the packets processed (someone’s sure to ask). You have to do all this (and more) while preserving high availability i.e. if one of the processors in the router goes down, you have to have a way to continue processing without interruption (the customer won’t be happy with a “choppy” VoIP conversation, right?). And all this has to be achieved without ANY intervention from a human operator – the router is most likely to be in a remote location – it must JUST CONTINUE TO WORK CORRECTLY, even when bad things happen. How is this implemented? As soon as a packet arrives, it is interpreted by the receiving software. The software decodes the packet headers in order to determine the destination, kind of packet (e.g. voice vs. data), SLAs associated with the “owner” of the packet etc. It looks up the internal database of “rules” of how to process this packet and handles the packet accordingly. The software might choose to hold on to the packet safely for some period of time, if it’s a low priority packet. Ah – this sounds very much like a database problem. For each packet, you have to minimally · Look up the most efficient next “hop” towards the destination. The “most efficient” next hop can change, depending on latency, availability etc. · Look up the SLA and determine the priority of this packet (e.g. voice calls get priority over data ftp) · Look up security information associated with this data packet. It may be necessary to retrieve the context for this network packet since a network packet is a small “slice” of a session. The context for the “header” packet needs to be stored in the router, in order to make this work. · If the priority of the packet is low, then “store” the packet temporarily in the router until it is time to forward the packet to the next hop. · Update various statistics about the packet. In most cases, you have to do all this in the context of a single transaction. For example, you want to look up the forwarding address and perform the “send” in a single transaction so that the forwarding address doesn’t change while you’re sending the packet. So, how do you do all this? Berkeley DB is a proven, reliable, high performance, highly available embeddable database, designed for exactly these kinds of usage scenarios. Berkeley DB is a robust, reliable, proven solution that is currently being used in these scenarios. First and foremost, Berkeley DB (or BDB for short) is very very fast. It can process tens or hundreds of thousands of transactions per second. It can be used as a pure in-memory database, or as a disk-persistent database. BDB provides high availability – if one board in the router fails, the system can automatically failover to another board – no manual intervention required. BDB is self-administering – there’s no need for manual intervention in order to maintain a BDB application. No need to send a technician to a remote site in the middle of nowhere on a freezing winter day to perform maintenance operations. BDB is used in over 200 million deployments worldwide for the past two decades for mission-critical applications such as the one described here. You have a choice of spending valuable resources to implement similar functionality, or, you could simply embed BDB in your application and off you go! I know what I’d do – choose BDB, so I can focus on my business problem. What will you do? /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;}

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