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  • Generate non-identity primary key

    - by MikeWyatt
    My workplace doesn't use identity columns or GUIDs for primary keys. Instead, we retrieve "next IDs" from a table as needed, and increment the value for each insert. Unfortunatly for me, LINQ-TO-SQL appears to be optimized around using identity columns. So I need to query and update the "NextId" table whenever I perform an insert. For simplicity, I do this immediately creating the new object. Since all operations between creation of the data context and the call to SubmitChanges are part of one transaction, do I need to create a separate data context for retrieving next IDs? Each time I need an ID, I need to query and update a table inside a transaction to prevent multiple apps from grabbing the same value. Is a separate data context the only way, or is there something better I could try?

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  • PHP/MYSQL Trouble Selecting by Primary Key

    - by djs22
    Hi all, So I have a primary key column called key. I'm trying to select the row with key = 1 via this code: $query ="SELECT * FROM Bowlers WHERE key = '1'"; $result = mysql_query($query) or die(mysql_error()); For some reason, I'm getting this result: 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 'key = '1'' at line 1 The mysql statement works for using other keys, ie WHERE name = 'djs22'. Any ideas?

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  • Working with foreign keys - cannot insert

    - by Industrial
    Hi everyone! Doing my first tryouts with foreign keys in a mySQL database and are trying to do a insert, that fails for this reason: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails Does this mean that foreign keys restrict INSERTS as well as DELETES and/or UPDATES on each table that is enforced with foreign keys relations? Thanks! Updated description: Products ---------------------------- id | type ---------------------------- 0 | 0 1 | 3 ProductsToCategories ---------------------------- productid | categoryid ---------------------------- 0 | 0 1 | 1 Product table has following structure CREATE TABLE IF NOT EXISTS `alpha`.`products` ( `id` MEDIUMINT UNSIGNED NOT NULL AUTO_INCREMENT , `type` TINYINT(2) UNSIGNED NOT NULL DEFAULT 0 , PRIMARY KEY (`id`) , CONSTRAINT `prodsku` FOREIGN KEY (`id` ) REFERENCES `alpha`.`productsToSku` (`product` ) ON DELETE CASCADE, ON UPDATE CASCADE) ENGINE = InnoDB;

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  • MySQL Removing Some Foreign keys

    - by Drew
    I have a table whose primary key is used in several other tables and has several foreign keys to other tables. CREATE TABLE location ( locationID INT NOT NULL AUTO_INCREMENT PRIMARY KEY ... ) ENGINE = InnoDB; CREATE TABLE assignment ( assignmentID INT NOT NULL AUTO_INCREMENT PRIMARY KEY, locationID INT NOT NULL, FOREIGN KEY locationIDX (locationID) REFERENCES location (locationID) ... ) ENGINE = InnoDB; CREATE TABLE assignmentStuff ( ... assignmentID INT NOT NULL, FOREIGN KEY assignmentIDX (assignmentID) REFERENCES assignment (assignmentID) ) ENGINE = InnoDB; The problem is that when I'm trying to drop one of the foreign key columns (ie locationIDX) it gives me an "ERROR 1025 (HY000): Error on rename" error. How can I drop the column in the assignment table above without getting this error?

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  • Violation of primary key constraint, multiple users

    - by MC.
    Lets say UserA and UserB both have an application open and are working with the same type of data. UserA inserts a record into the table with value 10 (PrimaryKey='A'), UserB does not currently see the value UserA entered and attempts to insert a new value of 20 (PrimaryKey='A'). What I wanted in this situation was a DBConcurrencyException, but instead what I have is a primary key violation. I understand why, but I have no idea how to resolve this. What is a good practice to deal with such a circumstance? I do not want to merge before updating the database because I want an error to inform the user that multiple users updated this data.

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  • JPA 2.0 Eclipse Link ... Composite primary keys

    - by Parhs
    I have two entities(actually more but it doenst matter) Exam and Exam_Normals Its a oneToMany relationship... The problem is that i need a primary key for Exams_Normals PK (Exam_ID Item) Item should be 1 2 3 4 5 etc.... But cant achieve it getting errors An alternative would be to: I cound use an IDENTITY and a ManyToOne relationship at Exam_Normals but that should be like PK(Exam_Normals_ID) and a reference to Exam and an extra collumn Item to keep an order.. SO 3 collumns But to avoid the alternative tried I tried with @IdClass and got errors Tried @EmbeddedID everything nothing works Any idea??

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  • Backup those keys, citizen

    - by BuckWoody
    Periodically I back up the keys within my servers and databases, and when I do, I blog a reminder here. This should be part of your standard backup rotation – the keys should be backed up often enough to have at hand and again when they change. The first key you need to back up is the Service Master Key, which each Instance already has built-in. You do that with the BACKUP SERVICE MASTER KEY command, which you can read more about here. The second set of keys are the Database Master Keys, stored per database, if you’ve created one. You can back those up with the BACKUP MASTER KEY command, which you can read more about here. Finally, you can use the keys to create certificates and other keys – those should also be backed up. Read more about those here. Anyway, the important part here is the backup. Make sure you keep those keys safe! Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • Is there a canonical source supporting "all-surrogates"?

    - by user61852
    Background The "all-PK-must-be-surrogates" approach is not present in Codd's Relational Model or any SQL Standard (ANSI, ISO or other). Canonical books seems to elude this restrictions too. Oracle's own data dictionary scheme uses natural keys in some tables and surrogate keys in other tables. I mention this because these people must know a thing or two about RDBMS design. PPDM (Professional Petroleum Data Management Association) recommend the same canonical books do: Use surrogate keys as primary keys when: There are no natural or business keys Natural or business keys are bad ( change often ) The value of natural or business key is not known at the time of inserting record Multicolumn natural keys ( usually several FK ) exceed three columns, which makes joins too verbose. Also I have not found canonical source that says natural keys need to be immutable. All I find is that they need to be very estable, i.e need to be changed only in very rare ocassions, if ever. I mention PPDM because these people must know a thing or two about RDBMS design too. The origins of the "all-surrogates" approach seems to come from recommendations from some ORM frameworks. It's true that the approach allows for rapid database modeling by not having to do much business analysis, but at the expense of maintainability and readability of the SQL code. Much prevision is made for something that may or may not happen in the future ( the natural PK changed so we will have to use the RDBMS cascade update funtionality ) at the expense of day-to-day task like having to join more tables in every query and having to write code for importing data between databases, an otherwise very strightfoward procedure (due to the need to avoid PK colisions and having to create stage/equivalence tables beforehand ). Other argument is that indexes based on integers are faster, but that has to be supported with benchmarks. Obviously, long, varying varchars are not good for PK. But indexes based on short, fix-length varchar are almost as fast as integers. The questions - Is there any canonical source that supports the "all-PK-must-be-surrogates" approach ? - Has Codd's relational model been superceded by a newer relational model ?

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  • RSA keys - virtual hosts

    - by Bosworth99
    Pardon my noobness, but I just got started with VPS (linux) hosting; setting up passwordless ssh for multiple users has proved to be kind of a pain. Currently I'm the single user of this ubuntu 10.04 LTS VPS (linode.com). I was able to establish a single rsa passkey under my home/user/.ssh/authorized_keys location. Fine. PuTTy works as expected, and Filezilla (sftp) links up as required. I've been working on a single site that this user owns, and thats not been a problem. Now, I want to set up some other sites, and I've chosen Webmin with the VirtualMin plugin to make this work. I made another user (or, rather, virtualmin did), but I've been unable to get FileZilla to link up to this new user. Could anyone with experience here explain what the setup is supposed to look like? IE - can I use a single rsa key pair for all accounts (if, for example, I give ownership of files to the original user?). Or is it standard practice to create a separate key pair for each user, and establish a separate putty/filezilla login for each? I've spent enough time dinking around with this to be frustrated. "Sever rejected the provided key" error sucks after the fifth hour. I'm about to set up an ftp server and call it a day. Any thoughts would be most welcome -

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  • Delete duplicate records from a SQL table without a primary key

    - by Shyju
    I have the below table with the below records in it create table employee ( EmpId number, EmpName varchar2(10), EmpSSN varchar2(11) ); insert into employee values(1, 'Jack', '555-55-5555'); insert into employee values (2, 'Joe', '555-56-5555'); insert into employee values (3, 'Fred', '555-57-5555'); insert into employee values (4, 'Mike', '555-58-5555'); insert into employee values (5, 'Cathy', '555-59-5555'); insert into employee values (6, 'Lisa', '555-70-5555'); insert into employee values (1, 'Jack', '555-55-5555'); insert into employee values (4, 'Mike', '555-58-5555'); insert into employee values (5, 'Cathy', '555-59-5555'); insert into employee values (6 ,'Lisa', '555-70-5555'); insert into employee values (5, 'Cathy', '555-59-5555'); insert into employee values (6, 'Lisa', '555-70-5555'); I dont have any primary key in this table .But i have the above records in my table already. I want to remove the duplicate records which has the same value in EmpId and EmpSSN fields. Ex : Emp id 5 Can any one help me to frame a query to delete those duplicate records Thanks in advance

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  • Primary Key Identity Value Increments On Unique Key Constraint Violation

    - by Jed
    I have a SqlServer 2008 table which has a Primary Key (IsIdentity=Yes) and three other fields that make up a Unique Key constraint. In addition I have a store procedure that inserts a record into the table and I call the sproc via C# using a SqlConnection object. The C# sproc call works fine, however I have noticed interesting results when the C# sproc call violates the Unique Key constraint.... When the sproc call violates the Unique Key constraint, a SqlException is thrown - which is no surprise and cool. However, I notice that the next record that is successfully added to the table has a PK value that is not exactly one more than the previous record - For example: Say the table has five records where the PK values are 1,2,3,4, and 5. The sproc attempts to insert a sixth record, but the Unique Key constraint is violated and, so, the sixth record is not inserted. Then the sproc attempts to insert another record and this time it is successful. - This new record is given a PK value of 7 instead of 6. Is this normal behavior? If so, can you give me a reason why this is so? (If a record fails to insert, why is the PK index incremented?) If this is not normal behavior, can you give me any hints as to why I am seeing these symptoms?

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  • what's the performance difference between int and varchar for primary keys

    - by user568576
    I need to create a primary key scheme for a system that will need peer to peer replication. So I'm planning to combine a unique system ID and a sequential number in some way to come up with unique ID's. I want to make sure I'll never run out of ID's, so I'm thinking about using a varchar field, since I could always add another character if I start running out. But I've read that integers are better optimized for this. So I have some questions... 1) Are integers really better optimized? And if they are, how much of a performance difference is there between varchars and integers? I'm going to use firebird for now. But I may switch later. Or possibly support multiple db's. So I'm looking for generalizations, if that's possible. 2) If integers are significantly better optimized, why is that? And is it likely that varchars will catch up in the future, so eventually it won't matter anyway? My varchar keys won't have any meaning, except for the unique system ID part. But I may want to obscure that somehow. Also, I plan to efficiently use all the bits of each character. I don't, for example, plan to code the integer 123 as the character string "123". So I don't think varchars will require more space than integers.

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  • How do you hit modifier keys when touch typing?

    - by Bob Ueland
    I am a programmer and I want to learn to touch type. As all programmers know, using modifier keys like Control, Command and Alt are essential. When programming I think that every second or third word I use involves a modifier key. But most touch typing learning software do not address these keys, it is as if they do not exist. Not only do they not let you practice them, they do not even tell you which fingers to use to hit them. Actually there is a touch typing game that I use called StarTyper (http://lidenanna.com) that lets you practice modifier keys and even make up your own custom words containing modifier keys. But not even this game tells you which fingers to use when hitting the modifier keys. Has anybody addressed this problem. Or are there just homespun methods that work for one person but not for the other?

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  • Foreign keys vs partitioning

    - by Industrial
    Hi! Since foreign keys are not supported by partitioned mySQL databases for the moment, I would like to hear some pro's and con's for a read-heavy application that will handle around 1-400 000 rows per table. Unfortunately, I dont have enough experience yet in this area to make the conclusion by myself... Thanks a lot! References: http://stackoverflow.com/questions/1537219/how-to-handle-foreign-key-while-partitioning http://stackoverflow.com/questions/2496140/mysql-partitioning-with-foreign-keys

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  • Sort array by keys of another array.

    - by marbrun
    Hello There are 2 arrays, both with the same length and with the same keys: $a1 = [1=>2000,65=>1354,103=>1787]; $a2 = [1=>'hello',65=>'hi',103=>'goodevening']; asort($a1); The keys of a1 and a2 are id's from a database. a1 gets sorted by value. Once sorted, how can we use the same sorting order in a2? Thanks!

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  • Foreign keys and pagination

    - by whitstone86
    This is my pagination script: <?php /*********************************** * PhpMyCoder Paginator * * Created By PhpMyCoder * * 2010 PhpMyCoder * * ------------------------------- * * You may use this code as long * * as this notice stays intact and * * the proper credit is given to * * the author. * ***********************************/ ?> <head> <title> Pagination Test - Created By PhpMyCoder</title> <style type="text/css"> #nav { font: normal 13px/14px Arial, Helvetica, sans-serif; margin: 2px 0; } #nav a { background: #EEE; border: 1px solid #DDD; color: #000080; padding: 1px 7px; text-decoration: none; } #nav strong { background: #000080; border: 1px solid #DDD; color: #FFF; font-weight: normal; padding: 1px 7px; } #nav span { background: #FFF; border: 1px solid #DDD; color: #999; padding: 1px 7px; } </style> </head> <?php //Require the file that contains the required classes include("pmcPagination.php"); //PhpMyCoder Paginator $paginator = new pmcPagination(20, "page"); //Connect to the database mysql_connect("localhost","root","PASSWORD"); //Select DB mysql_select_db("tvguide"); //Select only results for today and future $result = mysql_query("SELECT programme, channel, airdate, expiration, episode, setreminder FROM epdata1 where airdate >= now() order by expiration GROUP BY airdate"); //You can also add reuslts to paginate here mysql_data_seek($queryresult,0) ; while($row = mysql_fetch_array($result)) { $paginator->add(new paginationData($row['programme'], $row['channel'], $row['airdate'], $row['expiration'], $row['episode'], $row['setreminder'])); } ?> <?php //Show the paginated results $paginator->paginate (); ?><? include("pca-footer1.php"); ?> <?php //Show the navigation $paginator->navigation(); ?> However, I have two tables in this, and they are epdata1 (where the airtimes for my show House M.D. are) and housemdep plus the setreminder table. How can I use foreign keys in relation to this? I'm not sure if this will work for my script, but am willing to try. What I would like to do is to select certain episodes from the table housemdep (episodes of the show) and if any are selected it shows them as this: House M.D. showing on Channel 1 June 6th - 8:00pm "Wilson" Set Reminder House M.D. showing on Channel 1 June 7th - 1:30am "Wilson" Set Reminder House M.D. showing on Channel 1 June 7th - 12:55pm "House's Head" Set Reminder or like this, if I have not selected an episode from the row: House M.D. showing on Channel 1 June 7th - 8:00pm "House's Head" Set Reminder House M.D. showing on Channel 1 June 8th - 9:00pm Set Reminder House M.D. showing on Channel 1 June 9th - 2:30pm Set Reminder House M.D. showing on Channel 1 June 7th - 8:00pm "Que Sera Sera" Set Reminder Foreign keys and relationship of interlinked tables are new to me, if anyone could help I'd appreciate this. I've tried some of what Google suggested on foreign keys in another version of this script (this is a clone of the original on my localhost server running Apache and PHP 5.28/MySQL), but am not sure how to implement this. Thanks.

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  • what web based tool, to allow a non-technical user to manage authorized keys files on a Linux (fedora/centos/ubuntu/debian) server

    - by Tom H
    (Edit: clarification below) We have a number of groups of developers that change frequently, and a security policy to require individual logins to servers using rsa or dsa public keys, which is achieved via the standard method of adding id_dsa.pub to their authorized keys file. I am using chef to sync the user accounts across machines, however our previous method of using webmin to manage the user passwords is not designed for key based auth, and hence is not easy to use for non-technical users. The developers are logging in from the WAN using ssh, they can either provide their own key, or an administrator will send them a private key. The development machines are located in the cloud and we have a single server available to host the master set of accounts. Obviously I could deploy ldap or other centralised authentication system, but that seems a bit over blown when webmin worked well for the simple case. It is easy to achieve synchronised users, groups and passwords across a bunch of low security development boxes using webmin clustered users and groups. However looking at the currently installed webmin it is not so easy to create the authorized keys as it is to create user accounts and passwords. (its possible, but its not easy - some functionality is in the usermin module, or would required some tedious steps) Ideally I'd like a web interface that is pretty much dedicated to creating users and groups, and can generate key pairs on the fly, and can accepted pasted in public keys to add to the users authorized keys file. If the tool sync'ed the users and keys as well, that would be great, but I can use chef to do that part if the accounts are created correctly on the "master" server.

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  • [Linq to SQL] Multiple foreign keys to the same table

    - by cdonner
    I have a reference table with all sorts of controlled value lookup data for gender, address type, contact type, etc. Many tables have multiple foreign keys to this reference table I also have many-to-many association tables that have two foreign keys to the same table. Unfortunately, when these tables are pulled into a Linq model and the DBML is generated, SQLMetal does not look at the names of the foreign key columns, or the names of the constraints, but only at the target table. So I end up with members called Reference1, Reference2, ... not very maintenance-friendly. Example: <Association Name="tb_reference_tb_account" Member="tb_reference" <====== ThisKey="shipping_preference_type_id" OtherKey="id" Type="tb_reference" IsForeignKey="true" /> <Association Name="tb_reference_tb_account1" Member="tb_reference1" <====== ThisKey="status_type_id" OtherKey="id" Type="tb_reference" IsForeignKey="true" /> I can go into the DBML and manually change the member names, of course, but this would mean I can no longer round-trip my database schema. This is not an option at the current stage of the model, which is still evolving. Splitting the reference table into n individual tables is also not desirable. I can probably write a script that runs against the XML after each generation and replaces the member name with something derived from ThisKey (since I adhere to a naming convention for these types of keys). Has anybody found a better solution to this problem?

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  • send arrow keys using ganymed ssh java

    - by José Ramón Pérez Rubio
    I am using Ganymed ssh to connect to a remote machine and apart from sending commands I need to send the arrows keys (left and right keys). I can send commands but when I send the arrows keys nothing happends. This is what I have: public boolean createShell() throws Exception { try { // ... m_session= connection.openSession(); m_commandWriter = new OutputStreamWriter(m_session.getStdin()); String encoding=m_commandWriter.getEncoding(); //encoding is UFT8 m_errorPipe=new SSHSyncPipe(m_session.getStderr()); m_outputPipe=new SSHSyncPipe(m_session.getStdout()); m_outputPipe.start(); m_errorPipe.start(); // m_session.requestPTY("bash"); m_session.requestDumbPTY(); m_session.startShell(); m_shellCreated=true; return true; } } So if I use m_commandWriter.write(ls"\r\n"); m_commandWriter.flush(); It works, but m_commandWriter.write(37);//37 is the code for left arrow m_commandWriter.flush(); Doesn't work. Does anyone know what I am doing wrong? Thank you

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  • trying to setup multiple primary partitions on ubuntu linux

    - by JohnMerlino
    I currently have ubuntu desktop installed on a harddrive. I want to partition the harddrive so that I can reserve 30 gigs for ubuntu server and 30 gigs for ubuntu desktop. The drive has 300 gigs available. Right now I am booting from dvd drive and installing ubuntu server. I selected "Guided partitioning" and created a 30 gig primary partition of Ext4 journaling filesystem, set "yes, format it" for format partition and set bootable flag to on. I intend to use this 30 gig partition to hold ubuntu server and allow me to boot from it. Now I have two other partitions. They are both set to "logical", one is currently using 285.8 gigs and is using ext4 (when I try to set bootable flag to true, it gives a warning "You are trying to set the bootable flag on a logical partition. The bootable flag is only useful on the primary partitions"). More alarming it says "No existing file system was detected in this partition". Actually, Im thinking that this is the parittion that is supposed to be holding my current Ubuntu Desktop. And of course I want this to be bootable and be a primary partition, so I could dual boot from this and the server partition. Now the third partition is also set to logical and it is being used as swap area. My question is regarding that second partition. Its supposed to be a primary partition thats holding my existing ubuntu desktop edition. How do I switch it to primary and to make sure that its pointing to my existing desktop installation?

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  • Foreign Keys and Primary Keys at the same time

    - by Bader
    hello , i am trying to create table (orderdetails) , the table has two FKs and PKs at the same keys here is my code create table OrderDetails2 ( PFOrder_ID Number(3) PFProduct_ID Number(3) CONSTRAINT PF PRIMARY KEY (PFOrder_ID,PFProduct_ID), CONSTRAINT FK_1 FOREIGN KEY (PFProudct_ID) REFERENCES Product(Product_ID), CONSTRAINT FK_2 FOREIGN KEY (PFOrder_ID) REFERENCES Orderr(Order_ID) ); i am using Oracle express , a problem pops when i run the code , here is it ORA-00907: missing right parenthesis what is the problem ?

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  • How to re-enable function keys in byobu?

    - by Yang
    I was using byobu on Ubuntu 11.10 Server and I needed to hit a function key in an app, so I hit F9 to bring up the config menu and switched the keybinding set from "f-keys" to "screen-escape-keys". That worked, but now I can't re-enable all the f-keys. I found a program byobu-config that brings up the menu again, and I can switch back to screen keys from there. This fixes things for new screen processes, but the effect on the current screen session is weird: it disables the ctrl-a (screen) keys and restores F2-F8, but F9-F12 still don't do anything (they're just passed on to the foreground process). What's up with this? Any ideas? Thanks in advance.

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  • Can't make the Multimedia keys work in LXDE

    - by Uri Herrera
    I've tried to edit the configuration file in ~/.config/openbox/lxde-rc.xml however the changes don't take effect, i still can't use the keys. The LXDE wiki shows that after finding that my keyboard sends the correct standardized keyboard events i should go and edit the file to my liking, the keyboard does send the correct events and the keys are properly identified yet nothing happens. Since LXDE doesn't come with a sound preferences option i have installed xfce4-mixer. I too have a netbook running Lubuntu and it's media keys are working fine, i don't know if what i installed has had something to do here?. I also installed xfce4-volumed volume keys daemon from synaptic but to no avail, still nothing. How can i make the multimedia keys of my keyboard work in LXDE with xfce4-mixer Edit: Here is my lxde-rc.xml file

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