I was going through the JPA 2 specification and found two statements that sounds contradictory to me.   &quot;If X is a preexisting managed entity, it is ignored by the persist operation.&quot; - Pg 76  &quot;The EntityExistsException may thrown by the persistence provider when the persist operation is invoked and the entity already exists.&quot; - Pg 129    The statement 1 says something that sounds different from statement 2. So, my question is what is the difference between &quot;preexisting managed entity&quot; and &quot;entity already exists&quot;?
Hibernate has a handful of methods that, one way or another, takes your object and puts it into the database. What are the differences between them, when to use which, and why isn't there just one intelligent method that knows when to use what?  The methods that I have identified thus far are:   save() update() saveOrUpdate() saveOrUpdateCopy() merge() persist()
Inheriting constructors How do I delete my entire Stack Exchange account? Stack Exchange seems to have made it impossible to delete accounts. I can delete the accounts from other individual sites like Ask Ubuntu, but I can't delete the main account on stackexchange.com. I want to be rid of Stack Exchange completely! I don't want a Stack Exchange account whatsoever! I really don't like Stack Exchange and I want nothing to do with it. Please help me delete my stackexchange.com account! How to backup 20+TB of data? We have a NAS server at the company I work for that is being used for storing photography sessions. Each session is approximately 100gb. Over the last couple of years this server has accumulated 10+ TB of data, and we are increasing the amount of photoshoots exponentially. I estimate that by the end of next year we will have 20+ TB stored on this NAS. We are currently backing this server up to tape using LTO-5 tapes with Symantec BackupExec. Since the size of this server has grown, full backups of this server are not completing overnight. Does anyone have any suggestion on how to backup this amount of data? Should we be backing it up to tape? Are there any other options which may be better? I need to sync the Downloads folder to iCloud and then all the downloads should automatically sync with iCloud.   I tried to:   Create a new Downloads folder in the terminal of MacBook in the Documents directory. Tried to move the default Download folder to the newly created folder.   When I tried to use the mv command to move the default Downloads folder to the newly created Downloads folder in Documents in the terminal, it gives permission denied error.  I am trying to achieve what was suggested by user PhillipHolmes in the below thread, please. Thank you:    Thank you On my MacBook Pro I have found that several applications seem to share the value for a find.  For example, I searched 'applestackexchange' in Safari's unified address bar, then I switch to Xcode and click into a Find field.  The first word of my search in Safari then appears there.  iTerm2 and Sublime Text 2 also seem to participate in this sharing.  Running latest Mountain Lion on  a 2012 MBP. How to install Blender from the official website I installed Blender from official Ubuntu repository but its version is always behind the version available from the official Blender website.  I'm aware that I can launch the program within the downloaded folder, but i want to replace the install version with a new version downloaded from the website?   It must be present in the unity launcher.  I'm also aware of the available PPA's that are available, however I just want to install Blender manually.  Thanks in advance How can I calculate magnification ratio I get by reversing a lens? I am looking for a way to mathematically determine the maximum magnification ratio that is possible/practical to achieve by reverse mounting a non-macro lens, prior to purchasing the lens.     See related questions: On Windows 10 Professional, with the November update (Build 10586, Version 1511) , is there any possibility to completely remove Windows Defender ?  I don't want to just disable Windows Defender.  I want to completely uninstall from my system. What circumstances can cause a question or answer to be deleted, and what does that actually mean?    How can a post be deleted? When can't I delete my own post? Can I still see my post even after it's deleted? Can I see a list of my deleted posts? How can I undelete one of my posts? What does deletion mean for a post? How do votes to delete work? What are the criteria for deletion? What else should I know about deleted posts? If I flag my question with a request to delete it, what will happen?       For more information, see the articles about  and  in the . Can I put 700c tires on rims made for 27 x 1.25"? IndentationError: unindent does not match any outer indentation level When I compile the Python code below, I get      IndentationError: unindent does not match any outer indentation level     import sys  def Factorial(n): # Return factorial     result = 1     for i in range (1,n):         result = result * i     print "factorial is ",result     return result   Why? Sometimes, on the internet, particularly in online games, I see people using the  indefinite article before someone's name: "I see a Joey" or "I hug a Polly". I know some of these people and I'm positive that they are from English-speaking countries, which means it is not a mistake, they do it intentionally.  I was always taught that articles are not used in front of people's names. Maybe it is some sort of slang? What does it mean, when the indefinite article is put in front of someone's name?  Edit: There is a group of people standing somewhere. And somebody, named Joey, appears. They all know Joey. And someone in this group says "I see a Joey". So it is used when someone sees his or her friend. But I don't understand why they use the indefinite article here. Get the name of an object's type Do I need to use The Loop on pages? I'm writing my first WordPress theme and have a question about the use of The Loop in page templates. The page templates I've looked at all follow basically the same pattern (example from Twenty Twelve):  &lt;?php while ( have_posts() ) : the_post(); ?&gt; &lt;?php get_template_part( 'content', 'page' ); ?&gt; &lt;?php comments_template( '', true ); ?&gt; &lt;?php endwhile; // end of the loop. ?&gt;   But a page will only have one post associated with it so iterating through the posts seems unnecessary. My page template is more readable and seems to work fine:  &lt;?php the_post(); the_title('&lt;h1&gt;', '&lt;/h1&gt;'); the_content(); ?&gt;   Is this a good practice? Are there any downsides? How do I undo 'git add' before commit? I mistakenly added files to Git using the command:  git add myfile.txt   I have not yet run git commit. Is there a way to undo this, so these files won't be included in the commit? I flagged a question, , as "low quality" but a moderator declined it. I thought that the post was a low quality one and would like to know why the moderator did not.  Hopefully shedding light on this matter will avail me of the knowledge to be a better flagger in future.  My logic was that mysql-fetch-row is not supposed to return an array of results. If it does than its name would be mysql-fetch-rows.  What's your take on the situation? I have a SCSI disk in a server (hardware Raid 1), 32G, ext3 filesytem. df tells me that the disk is 100% full. If I delete 1G this is correctly shown.  However, if I run a du -h -x / then du tells me that only 12G are used (I use -x because of some Samba mounts).  So my question is not about subtle differences between the du and df commands but about how I can find out what causes this huge difference?  I rebooted the machine for a fsck that went w/out errors. Should I run badblocks? lsof shows me no open deleted files, lost+found is empty and there is no obvious warn/err/fail statement in the messages file.  Feel free to ask for further details of the setup. If I'm playing the Hilltop farm in co-op - what farmer's mining level is used for the hilltop spawns? I've found a strange thing: some Stack Exchange sites have their own domain names instead of https://[site name].stackexchange.com. The websites which have their own domain names are:          Are there any parameters for allocating specific URLs to Stack Exchange sites? I would like to configure Apache 2 running on Kubuntu to execute Perl CGI scripts. I've tried some steps that I came across by googling, but nothing seems to work.  What is the right way of achieving this?