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  • Too many heap subpools might break the upgrade

    - by Mike Dietrich
    Recently one of our new upcoming Oracle Database 11.2 reference customers did upgrade their production database - a huge EBS system - from Oracle 9.2.0.8 to Oracle Database 11.2.0.2. They've tested very well, we've optimized the upgrade process, the recompilation timings etc.  But once the live upgrade was done it did fail in the JAVA component piece with this error: begin if initjvmaux.startstep('CREATE_JAVA_SYSTEM') then * ORA-29553: classw in use: SYS.javax/mail/folder ORA-06512: at "SYS.INITJVMAUX", line 23 ORA-06512: at line 5 Support diagnosis was pretty quick - and refered to:Bug 10165223 - ORA-29553: class in use: sys.javax/mail/folder during database upgrade But how could this happen? Actually I don't know as we have used the same init.ora setup on test and production. The only difference: the prod system has more CPUs and RAM. Anyway, the bug names as workarounds to either decrease the SGA to less than 1GB or decrease the number of heap subpools to 1. Finally this query did help to diagnose the number of heap subpools: select count(distinct kghluidx) num_subpools from x$kghlu where kghlushrpool = 1; The result was 2 - so we did run the upgrade now with this parameter set: _kghdsidx_count=1 And finally it did work well. One sad thing:After the upgrade did fail Support did recommend to restore the whole database - which took an additional 3-4 hours. As the ORACLE SERVER component has been already upgraded successfully at the stage where the error did happen it would have been fine to go on with the manual upgrade and start catupgrd.sql script. It would have been detected that the ORACLE SERVER is upgraded already and just picked up the non-upgraded components. The good news:Finally I had one extra slide to add to our workshop presentation

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  • Is realtime validation of username good or bad?

    - by iamserious
    I have a simple form for the user to sign up to my site; with email, username and password fields. We are now trying to implement an ajax validation so the user doesn't have to post the form to find out if the username is already taken. I can do this either on keyup event or on text blur event. My question is, which of these is really the best way to do? Keyup From the user POV, it would be good if the validation is done as and when they are typing, (on key up event) - of course, I am waiting for half a second to see if the user stops typing before firing off the request, and user can make any adjustments immediately. But this means I am sending way more requests than if I validated the username on Blur event. Blur The number of requests will be much lower when the validation is done on blur event, But this means the user has to actually go away from the textbox, look at the validation result, and if necessary go back to it to make any changes and repeat the whole process until he gets it right. I had a quick look at google, tumblr, twitter and no one actually does username validations on keyup events, (heck, tubmlr waits for the form to be posted) but I can swear I have seen keyup validations in a lot of places too. So, coming back to the question, will keyup validations be too many for server, is it an unnecessary overhead? or is it worth taking these hits to give user a better experience? ps: all my regex validations etc are already done on javascript and only when it passes all these other criteria does it send a request to server to check if a username already exists. (And the server is doing a select count(1) from user where username = '' - nothing substantial, but still enough to occupy some resource) pps: I'm on asp.net, MS SQL stack., if that matters.

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  • Bad anti-aliasing in some applications

    - by Matty
    There was an update a few weeks ago that seemed to mess with anti-aliasing in some applications. Firefox, Thunderbird, and the text in some apps such as Mousepad and Leafpad (but not the rest of the window) are affected, whereas Chrome and everything else seems to be just fine. Attached are two screenshots showing the difference between rendering in Firefox and Chrome. The anti-aliasing settings are the same as they've always been, which have worked just fine - full hinting, RGB sub-pixel order. I'm really not sure what's going on and am thinking that it might be faster to fix this problem by re-installing, but is there anything I can try first as re-installing is the last thing I want to do? I'm running Xubuntu 12.04.

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  • Google is good or bad for programmer? [closed]

    - by Vikas
    Recently I was being interviewed by a company and faced one question. The interviewer asked me a question and at that time I didn't know the answer but if I had been asked about just 4 months ago, I could have answered it. The question was from new language that I learned just 4 months ago. But I just get overview of the language and just get started working on that. Whenever I face difficultly, I google it. That means we do not have to memorize the whole programming language book! So in that situation I felt that Google screwed my job! Not talking subjectively, Is it good to google all the time?

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  • Bad SEO Advice - 3 Myths

    The world is awash with SEO. Business users are deluged with tips, tricks and advice on how to achieve top page ranking success. You only need to take a quick look around a Google search on SEO to see for yourself the weight and variety of information out there.

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  • is there any elegant way to analyze an engineer's process?

    - by NewAlexandria
    Plenty of sentiment exists that measuring commits is inappropriate. Has any study been done that tries to draw in more sources than commits - such as: browsing patterns IDE work (pre-commit) idle time multitasking I can't think of an easy way to do these measures, but I wonder if any study has been done. On a personal note, I do believe that reflection on one's own 'metrics' could be valuable regardless of (or in the absence of) using these for performance eval. I.E. an un-biased way to reflect on your habits. But this is a discussion matter beyond Q&A.

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  • Examples of bad variable names and reasons [on hold]

    - by user470184
    I'll start with a class in the jdk package : public final class Sdp { should be : public final class SocketsDirectProtocol { Sdp is class name, this is ambigious, should be : Class<?> cl = Class.forName("java.net.SdpSocketImpl", true, null); should be : Class<?> clazz = Class.forName("java.net.SdpSocketImpl", true, null); cl is ambiguous private static void setAccessible(final AccessibleObject o) { should be : private static void setAccessible(final AccessibleObject accessibleObject) { There are various other examples in this class, do you have similar and/or differing examples of variables that were named badly ? package com.oracle.net; public final class Sdp { private Sdp() { } /** * The package-privage ServerSocket(SocketImpl) constructor */ private static final Constructor<ServerSocket> serverSocketCtor; static { try { serverSocketCtor = (Constructor<ServerSocket>) ServerSocket.class.getDeclaredConstructor(SocketImpl.class); setAccessible(serverSocketCtor); } catch (NoSuchMethodException e) { throw new AssertionError(e); } } /** * The package-private SdpSocketImpl() constructor */ private static final Constructor<SocketImpl> socketImplCtor; static { try { Class<?> cl = Class.forName("java.net.SdpSocketImpl", true, null); socketImplCtor = (Constructor<SocketImpl>)cl.getDeclaredConstructor(); setAccessible(socketImplCtor); } catch (ClassNotFoundException e) { throw new AssertionError(e); } catch (NoSuchMethodException e) { throw new AssertionError(e); } } private static void setAccessible(final AccessibleObject o) { AccessController.doPrivileged(new PrivilegedAction<Void>() { public Void run() { o.setAccessible(true); return null; } }); } /** * SDP enabled Socket. */ private static class SdpSocket extends Socket { SdpSocket(SocketImpl impl) throws SocketException { super(impl); } } /** * Creates a SDP enabled SocketImpl */ private static SocketImpl createSocketImpl() { try { return socketImplCtor.newInstance(); } catch (InstantiationException x) { throw new AssertionError(x); } catch (IllegalAccessException x) { throw new AssertionError(x); } catch (InvocationTargetException x) { throw new AssertionError(x); } } /** * Creates an unconnected and unbound SDP socket. The {@code Socket} is * associated with a {@link java.net.SocketImpl} of the system-default type. * * @return a new Socket * * @throws UnsupportedOperationException * If SDP is not supported * @throws IOException * If an I/O error occurs */ public static Socket openSocket() throws IOException { SocketImpl impl = createSocketImpl(); return new SdpSocket(impl); } /** * Creates an unbound SDP server socket. The {@code ServerSocket} is * associated with a {@link java.net.SocketImpl} of the system-default type. * * @return a new ServerSocket * * @throws UnsupportedOperationException * If SDP is not supported * @throws IOException * If an I/O error occurs */ public static ServerSocket openServerSocket() throws IOException { // create ServerSocket via package-private constructor SocketImpl impl = createSocketImpl(); try { return serverSocketCtor.newInstance(impl); } catch (IllegalAccessException x) { throw new AssertionError(x); } catch (InstantiationException x) { throw new AssertionError(x); } catch (InvocationTargetException x) { Throwable cause = x.getCause(); if (cause instanceof IOException) throw (IOException)cause; if (cause instanceof RuntimeException) throw (RuntimeException)cause; throw new RuntimeException(x); } } /** * Opens a socket channel to a SDP socket. * * <p> The channel will be associated with the system-wide default * {@link java.nio.channels.spi.SelectorProvider SelectorProvider}. * * @return a new SocketChannel * * @throws UnsupportedOperationException * If SDP is not supported or not supported by the default selector * provider * @throws IOException * If an I/O error occurs. */ public static SocketChannel openSocketChannel() throws IOException { FileDescriptor fd = SdpSupport.createSocket(); return sun.nio.ch.Secrets.newSocketChannel(fd); } /** * Opens a socket channel to a SDP socket. * * <p> The channel will be associated with the system-wide default * {@link java.nio.channels.spi.SelectorProvider SelectorProvider}. * * @return a new ServerSocketChannel * * @throws UnsupportedOperationException * If SDP is not supported or not supported by the default selector * provider * @throws IOException * If an I/O error occurs */ public static ServerSocketChannel openServerSocketChannel() throws IOException { FileDescriptor fd = SdpSupport.createSocket(); return sun.nio.ch.Secrets.newServerSocketChannel(fd); } }

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  • Associative array challenges, or examples?

    - by Aerovistae
    I understand well when and how to use an associative array, but I'm trying to teach a friend to program and I'm having some trouble with this particular concept. I need a good set of problems whose solutions are best implemented through the use of maps/hashes/associative arrays/dictionaries. I googled all over and couldn't find any. I was hoping someone might know of some, or perhaps get a community wiki sort of answer. That way I can say, here's our problem, and here's how we could effectively solve it through the use of an associative array... It's one of those cases where when I'm programming and I run into a situation that calls for a dictionary, I recognize it, but I can't seem to make up any such situations to use for a demonstration.

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  • Automatic Maintenance Jobs in every PDB? New SPM Evolve Advisor Task in Oracle 12.1.0.2

    - by Mike Dietrich
    A customer checking out our slides from the OTN Tour in August 2014 asked me a finicky question the other day: "According to the documentation the Automatic SQL Tuning Advisor maintenance task gets executed only within the CDB$ROOT, but not within each PDB - but the slides are not clear here. So what is the truth?" Ok, that's good question. In my understanding all tasks will get executed within each PDB - that's why we recommend (based on experience) to break up the default maintenance windows when using Oracle Multitenant. Otherwise all PDBs will have the same maintenance windows, and guess what will happen when 25 PDBs start gathering object statistics at the same time ... The documentation indeed says: Automatic SQL Tuning Advisor data is stored in the root. It might have results about SQL statements executed in a PDB that were analyzed by the advisor, but these results are not included if the PDB is unplugged. A common user whose current container is the root can run SQL Tuning Advisor manually for SQL statements from any PDB. When a statement is tuned, it is tuned in any container that runs the statement. This sounds reasonable. But when we have a look into our PDBs or into the CDB_AUTOTASK_CLIENT view the result is different from what the doc says. In my environment I did create just two fresh empty PDBs (CON_ID 3 and 4): SQL> select client_name, status, con_id from cdb_autotask_client; CLIENT_NAME                           STATUS         CON_ID------------------------------------- ---------- ----------auto optimizer stats collection       ENABLED             1sql tuning advisor                    ENABLED             1auto space advisor                    ENABLED             1auto optimizer stats collection       ENABLED             4sql tuning advisor                    ENABLED             4auto space advisor                    ENABLED             4auto optimizer stats collection       ENABLED             3sql tuning advisor                    ENABLED             3auto space advisor                    ENABLED             3 9 rows selected. I haven't verified the reason why this is different from the docs but it may have been related to one change in Oracle Database 12.1.0.2: The new SPM Evolve Advisor Task ( SYS_AUTO_SPM_EVOLVE_TASK) for automatic plan evolution for SQL Plan Management. This new task doesn't appear as a stand-alone job (client) in the maintenance window but runs as a sub-entity of the Automatic SQL Tuning Advisor task. And (I'm just guessing) this may be one of the reasons why every PDB will have to have its own Automatic SQL Tuning Advisor task  Here you'll find more information about how to enable, disable and configure the new Oracle 12.1.0.2 SPM Evolve Advisor Task: Oracle Database 12.1.0.2 SQL Tuning Guide:Managing the SPM Evolve Advisor Task -Mike

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  • Rapid Application Development, good, bad or ugly?

    - by chrisw
    I have been working for such a shop for the past three years and I know deep down it cannot be like this everywhere. When I think of Rapid Application Development I immediately think programming without fore-thought. For example, when my company decides to come out with a new product, they don't do any type of relationship mapping, no ER diagrams, no round table discussions on expandability. No, the senior developer that ends up working on the product puts together a screen shot walk-through of the application to show to the client. Once the client signs off on the project work is underway by the senior developer. Now you have a senior developer (I use that term "senior" loosely) coding the application in under a week with no unit testing. Well I guess the good to this is it keeps programmers employed due to the enormous amount of unforeseen "features" in the newly created application. Have any of you dealt with a company like this? If you did how did you preserve your sanity?

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  • Why enumerator structs are a really bad idea

    If you've ever poked around the .NET class libraries in Reflector, you probably would have noticed that the generic collection classes all have implementations of their IEnumerator as a struct rather than a class. As you will see, this design decision has some rather unfortunate side effects......Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • UPK at Oracle OpenWorld 2012!

    - by Karen Rihs
    Oracle OpenWorld 2012 September 30 – October 4, 2012 in San Francisco, CA We hope to see you at Oracle OpenWorld this year!  Please see the Focus On User Productivity Kit document for details of the many UPK sessions, hands-on labs, demonstrations, and networking opportunities available to you!  Be sure to stop by one of our two demo pods to say “hello”.  We’d love to hear about how you’re using UPK!

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  • Can too much abstraction be bad?

    - by m3th0dman
    As programmers I feel that our goal is to provide good abstractions on the given domain model and business logic. But where should this abstraction stop? How to make the trade-off between abstraction and all it's benefits (flexibility, ease of changing etc.) and ease of understanding the code and all it's benefits. I believe I tend to write code overly abstracted and I don't know how good is it; I often tend to write it like it is some kind of a micro-framework, which consists of two parts: Micro-Modules which are hooked up in the micro-framework: these modules are easy to be understood, developed and maintained as single units. This code basically represents the code that actually does the functional stuff, described in requirements. Connecting code; now here I believe stands the problem. This code tends to be complicated because it is sometimes very abstracted and is hard to be understood at the beginning; this arises due to the fact that it is only pure abstraction, the base in reality and business logic being performed in the code presented 1; from this reason this code is not expected to be changed once tested. Is this a good approach at programming? That it, having changing code very fragmented in many modules and very easy to be understood and non-changing code very complex from the abstraction POV? Should all the code be uniformly complex (that is code 1 more complex and interlinked and code 2 more simple) so that anybody looking through it can understand it in a reasonable amount of time but change is expensive or the solution presented above is good, where "changing code" is very easy to be understood, debugged, changed and "linking code" is kind of difficult. Note: this is not about code readability! Both code at 1 and 2 is readable, but code at 2 comes with more complex abstractions while code 1 comes with simple abstractions.

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  • Proving What You are Worth

    - by Ted Henson
    Here is a challenge for everyone. Just about everyone has been asked to provide or calculate the Return on Investment (ROI), so I will assume everyone has a method they use. The problem with stopping once you have an ROI is that those in the C-Suite probably do not care about the ROI as much as Return on Equity (ROE). Shareholders are mostly concerned with their return on the money the invested. Warren Buffett looks at ROE when deciding whether to make a deal or not. This article will outline how you can add more meaning to your ROI and show how you can potentially enhance the ROE of the company.   First I want to start with a base definition I am using for ROI and ROE. Return on investment (ROI) and return on equity (ROE) are ways to measure management effectiveness, parts of a system of measures that also includes profit margins for profitability, price-to-earnings ratio for valuation, and various debt-to-equity ratios for financial strength. Without a set of evaluation metrics, a company's financial performance cannot be fully examined by investors. ROI and ROE calculate the rate of return on a specific investment and the equity capital respectively, assessing how efficient financial resources have been used. Typically, the best way to improve financial efficiency is to reduce production cost, so that will be the focus. Now that the challenge has been made and items have been defined, let’s go deeper. Most research about implementation stops short at system start-up and seldom addresses post-implementation issues. However, we know implementation is a continuous improvement effort, and continued efforts after system start-up will influence the ultimate success of a system.   Most UPK ROI’s I have seen only include the cost savings in developing the training material. Some will also include savings based on reduced Help Desk calls. Using just those values you get a good ROI. To get an ROE you need to go a little deeper. Typically, the best way to improve financial efficiency is to reduce production cost, which is the purpose of implementing/upgrading an enterprise application. Let’s assume the new system is up and running and all users have been properly trained and are comfortable using the system. You provide senior management with your ROI that justifies the original cost. What you want to do now is develop a good base value to a measure the current efficiency. Using usage tracking you can look for various patterns. For example, you may find that users that are accessing UPK assistance are processing a procedure, such as entering an order, 5 minutes faster than those that don’t.  You do some research and discover each minute saved in processing a claim saves the company one dollar. That translates to the company saving five dollars on every transaction. Assuming 100,000 transactions are performed a year, and all users improve their performance, the company will be saving $500,000 a year. That $500,000 can be re-invested, used to reduce debt or paid to the shareholders.   With continued refinement during the life cycle, you should be able to find ways to reduce cost. These are the type of numbers and productivity gains that senior management and shareholders want to see. Being able to quantify savings and increase productivity may also help when seeking a raise or promotion.

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  • The old "do as I say, not as I do" problem

    - by AaronBertrand
    Microsoft is often considered a leader, an innovator, a trend-setter. The same could be said for Apple, Google, and a host of other tech companies. And each of those has its set of critics as well, who think that the company is the opposite - or worse. Some people think it is a good idea to model their own code, architecture or applications after things that these companies have done, but this is not always the best approach. Humans work at these companies too, and everyone is prone to mistakes,...(read more)

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  • Bad texture on model with different GPU

    - by Pacha
    I have some kind of distortion on the texture of my 3D model. It works perfectly well on an AMD GPU, but when testing on a integrated Intel HD graphics card it has a weird issue. I don't have a problem with the rest of my entities as they are not scaled. The models with the problems are scaled, as my engine supports different sizes for the platforms. I am using Ogre3D as rendering engine, and GLSL as shader language. Vertex shader: #version 120 varying vec2 UV; void main() { UV = gl_MultiTexCoord0; gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex; } Fragment shader: #version 120 varying vec2 UV; uniform sampler2D diffuseMap; void main(void) { gl_FragColor = texture(diffuseMap, UV); } Screenshot (the error is on the right and left side, the top and bottom part are rendered perfectly well):

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  • Migration a database from 32bit to 64bit

    - by Mike Dietrich
    Database migrations from an 32bit environment to an 64bit environment keeping the same platform architecture (e.g. moving an Oracle 10.2.0.5 database from MS Windows XP 32bit to MS Windows Server 2003 64bit) does not happen that often anymore. But still we see them getting done. And there are a few things to note when doing such a move. First of all the important question is:Will you upgrade your database as part of this move - Yes or No? If you say "Yes" then you are almost done with that topic as we will take care of that bitnes move during the upgrade. The only thing you have to take care is OLAP in case you are using OLAP Option with Analytic Workspaces (AW) by yourself. Those store data in Binary LOBs - and in order to move AWs from 32bit to 64bit you have to export your AWs prior to the move - and import them later on. People who don't use OLAP don't have to take care on this. But if you say "No" (meaning: no upgrade actions involved - you keep your database version) then you have to make sure to invalidate all packages and stored code in the database before you shutdown your database in the 32bit environment and prior to moving it over. And the same rule as above for OLAP applies once you use the OLAP Option. In the source environment: startup upgrade;    -- [or startup migrate; -- for Oracle 9i] @?/rdbms/admin/utlirp.sqlshutdown immediate In the destination environment: startup upgrade @?/olap/admin/xumuts.plb --Only if OLAP Option is installed@?/rdbms/admin/utlrp.sql The script utlirp.sql will invalidate all packages and stored code, utlrp.sql will recompile - and xumuts.plb will rebuild the OLAP Analytic Workspaces in case you have the OLAP Option installed.

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  • Test-only Members: Good or Bad?

    In the article, Dino focuses on two particular situations: dealing with dependencies and testing private members. He'll be discussing this in the context of ASP.NET MVC and MSTest, but without any significant loss of generality.

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  • Are null references really a bad thing?

    - by Tim Goodman
    I've heard it said that the inclusion of null references in programming languages is the "billion dollar mistake". But why? Sure, they can cause NullReferenceExceptions, but so what? Any element of the language can be a source of errors if used improperly. And what's the alternative? I suppose instead of saying this: Customer c = Customer.GetByLastName("Goodman"); // returns null if not found if (c != null) { Console.WriteLine(c.FirstName + " " + c.LastName + " is awesome!"); } else { Console.WriteLine("There was no customer named Goodman. How lame!"); } You could say this: if (Customer.ExistsWithLastName("Goodman")) { Customer c = Customer.GetByLastName("Goodman") // throws error if not found Console.WriteLine(c.FirstName + " " + c.LastName + " is awesome!"); } else { Console.WriteLine("There was no customer named Goodman. How lame!"); } But how is that better? Either way, if you forget to check that the customer exists, you get an exception. I suppose that a CustomerNotFoundException is a bit easier to debug than a NullReferenceException by virtue of being more descriptive. Is that all there is to it?

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  • EAV - is it really bad in all scenarios?

    - by Giedrius
    I'm thinking to use EAV for some of the stuff in one of the projects, but all questions about it in stackoverflow end up to answers calling EAV an anti pattern. But I'm wondering, if is it that wrong in all cases? Let's say shop product entity, it has common features, like name, description, image, price, etc., that take part in logic many places and has (semi)unique features, like watch and beach ball would be described by completely different aspects. So I think EAV would fit for storing those (semi)unique features? All this is assuming, that for showing product list, it is enough info in product table (that means no EAV is involved) and just when showing one product/comparing up to 5 products/etc. data saved using EAV is used. I've seen such approach in Magento commerce and it is quite popular, so may be there are cases, when EAV is reasonable?

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  • A follow up to yesterday

    - by GrumpyOldDBA
    As I have been asked,  here to tidy up yesterdays post is the procedure my startup procedure calls along with the logging table deployed in the DBA database. Just to muddy the water further I have routines for remotely calling the DBAMessages table through a remote server to send out email from a central server!! Just to explain that I have been ( previously ) limited to only using one Server to send email alerts for multiple Servers so I attempt to code to deal with all possible circumstances...(read more)

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