When and why should we use  over  or  methods?  Also do they use sync or asynch limits? I cannot find any clear documentation stating this.
I have been reading about the new Salesforce async triggers. Currently, I tend to handle these sort of needs with a trigger that passes data to a 'Handler class' that would evaluate if a certain change has occurred. If it has then we pass those Ids to a queueable class for further processing.   What advantage do CDC and async triggers offer over using queueable or batch apex?
Fast way of copying IMAP to IMAP on CentOS I'm trying to copy of IMAP emails from one server to my new server but after Googling for hours and trying several tools, nothing is working. Is there a tool that actually works?  I am copying hundreds of thousands of emails so using a email client is out of the question, I tried it, and at the rate of a email per 2 seconds, it would take a few weeks or months!  www.linux-france.org/prj/imapsync/ is commonly mentioned, however, the tool is no longer available.  I tried www.athensfbc.com/imap_tools/ which just hangs and does nothing.  Any migration tools that work? Tools for automating document compilation A lot of people write makefiles that say something like  paper.pdf: paper.tex         pdflatex paper         bibtex paper         pdflatex paper         pdflatex paper   To handle re-running TeX to get new/changed references and so forth. Is there a better way to do this? Is it possible to use "negative sound waves" to "cancel out" a sound to create silence? Received an email intended for another person I ran into the problem that my primary key sequence is not in sync with my table rows.   That is, when I insert a new row I get a duplicate key error because the sequence implied in the serial datatype returns a number that already exists.  It seems to be caused by import/restores not maintaining the sequence properly. Determinant of a matrix whose $(i,j)$th element is $|i-j|$? Question states: "Let $D_n$ denote the determinant of the $n$-by-$n$ matrix whose $(i,j)$th element (the element in the $i$th row and $j$th column) is the absolute value of the difference between $i$ and $j$. Show that $D_n = (-1)^{n-1}(n-1)2^{n-2}$."  It seems like that I can get a recurrence relation (especially the question was from a book chapter dealing with recursion). In trying to get a recurrence relation, here is what I have done so far:  (Let $R_k$ denote the $k$th row and let $(i,j)$ denote the element/spot of $i$th row and $j$th spot)  1) replace $R_1$ with $R_1-(R_2+R_{n-1})$ to get $R_1^*$  2) replace $R_1^*$ with $R_1^*+R_{n-2}$  3) If I am not mistaken, I should have $-2$ on $(1,1)$, $2$ on both $(1,n-1)$ and $(1,n)$, and all other element in the first row as $0$.  4) take out $2$ from the first row, and expand the determinant about the first row  5) I should have $D_n=2(-D_{n-1}+(-1)^n B_{n-1})$, where $B_{n-1}$ is the determinant of a not-easily-reducible mayrix whose last column consists of $n-1$ ones followed by one $-1$.  How should I go about from now on? Once I get a recurrence relation, it would be pretty easy to get the explicit formula for $D_n$ using induction.  P.S. This question apparently is a question taken from 1969 Putnam Competition How do I add a Pokestop to my area? How do I add a Pokestop to an area that has none? It is an area where there are tons of businesses but unless I drive about a mile from my work area there are no Pokestops.   I want to add one since we have 1000's of people in the work area, a lot of them play Pokemon Go, and we all can't leave work to drive a mile away to get to a Pokestop area.   Plus it would be nice to be able to capture Pokemon on our breaks. Listing feature classes with active domains? I'm struggling to find the limit at infinity of : $$\lim \limits_{n\rightarrow\infty}\sin^2(\pi\sqrt{n^2 + n}), n\in\Bbb N$$ I know it is $1$ but I don't understand why this is wrong :  $\sin^2(\pi\sqrt{n^2 + n}) = \sin^2(\pi*n\sqrt{1 + \frac{1}{n}})$.  So $\lim \limits_{n\rightarrow\infty}\sin^2(\pi\sqrt{n^2 + n}) = \lim \limits_{n\rightarrow\infty}\sin^2(\pi*n\sqrt{1 + \frac{1}{n}}) =  \lim \limits_{n\rightarrow\infty} \sin^2(\pi*n) = 0$.  Thanks. "Literally" and "Decimate" misuse Recently I've heard American TV commentators say "[a person] was literally decimated" and "[a Senator] was literally thrown under the bus". In the first case I think the person was not actually 10% killed, but in the second, I believe they meant that 57 members of the US Senate carried #58 onto Constitution Avenue and threw him under a (hopefully moving) bus.  Are usages like these normal or acceptable now? I find them grating, myself. Prove $\csc(x)=\sum_{k=-\infty}^{\infty}\frac{(-1)^k}{x+k\pi}$ Where can I ask questions regarding Electronics? I am currently doing some electronics and microcontroller programming, and I have a couple of questions to ask the people here.    Most of the questions are regarding wiring on breadboards and components.    On which of the websites (Stack Overflow, Server Fault, or Super User) should I ask these particular questions? A toplogical space $X$ is said to be second countable   if there exists a countable basis for the topology.      $X$ is separable if there exist a countable dense subset.   Show that a second countable space always is separable.      Give an example of a space that is separable but not    second countable   The first part was easy and i managed to solve it on my own  Assume that $X$ is second countable and let $B_1, B_2, B_3...$ be a countable basis. Construct the set $A$ by taking one element $x_n$ out of every $B_n$. Then $A$ becomes dense because every open set $U$ contain a $B_n$ which in turn contain the element $x_n$ in $A$.    Again, like in the question i posted yesterday, i had trouble to come up with an example but our professor gave an example during the last lecture but i dont fully understand it:  "For an example of a separable but not second countable space let $X$ be the real line provided with the cofinite topology, i.e. where a set is open if its either empty or if its complement is finite.   Then every infinite set is dense and hence $X$ is separable.  But for an arbitrary countable family of open sets $U_1, U_2...$ write $U_i = X$\ $A_i$, where $A_i$ is finite, there is an element $x \in X$\ $(\cup_i Ai)$, because $A_i$ is countable,  such that the open set $X$\ $\{x\}$ is then not able to contain any $U_i$. Consequently $X$ is not second countable."  We asked him to explain it in more detail but his english is poor and nobody understood anything...:)       Def: A subset $A$ of a topological space $X$ is dense in $X$ if for any point $x$ in $X$, any neighborhood of $x$ contains at least one point from $A$.   $1.$ "Then every infinite set is dense"  Take $A$ to be one of these infinite sets. If $x \in A \subset X$ then it trivially fulfills the definition. But if we take a $x \not\in A$ why is it not possible to find a neighborhood in these finite sets that does not contain an element in $A$?  edit: its obvious if it is only open neighborhoods, open sets in the topology, but that is not specified in the definition.  $2.$ I am not fully understanding this either  "But for an arbitrary countable family of open sets $U_1, U_2...$ write $U_i = X$\ $A_i$, where $A_i$ is finite, there is an element $x \in X$\ $(\cup_i Ai)$, because $A_i$ is countable,  such that the open set $X$\ $\{x\}$ is then not able to contain any $U_i$. Consequently $X$ is not second countable."  Is it possible to express this in a simpler way? What and how does Darth Vader see? Are there any sources that talk about  about Darth Vader's visual acuity?  His life-supporting armour is quite advanced but does it provide any useful augmentation to his visual abilities? Bug: biblatex can not deal name prefix like "van der ", Miktex updated on 2016.01.16 Firstly, hello everyone. I am new here : )  I am writing my phd thesis using MikTeX + TeXnicCenter and everything goes well, until I have updated MikTeX today.  My Problem:  The program gives an error message to the "same old" command:  \printbibliography[prefixnumbers={},notkeyword={Eigene}, notkeyword={Datenblatt}, title={Fremdliteratur}, heading=subbibliography]   The error message looks like this:  Undefined control sequence. &lt;argument&gt; ...nameprefix {van~der}\isdot }\ifprefchar    Investigation  I have found out that this error comes from the name prefix "van der". If I write them together without space in *.bib file and compile it, it works again.  What's the best way to fix this or work around it? Is it a bug? What's the easiest way to unrar a file? I just realized I can't unrar .rar files on my Ubuntu machine!  What's the easiest way to accomplish this fundamental task? If possible I'd love something like 7Zip that I can just right Click, and extract and have the program worry about how to do it regardless if it's a .zip, a .rar or a .foo compressed file. What is this Windows 8 icon for as rectangle icon in the title bar? Every Window in Windows 8 got this icon if it gots the focus. When clicking on it, nothing seems to happen.   How does this icon work? Under what conditions is the difference between a rank $1$, postive semidefinite matrix and a hermitian matrix positive semidefinite? Blown out blue/red light making photos look out of focus Tell rate-limited users how long they have to wait before asking a new question New users are limited to one question per an hour, but once they'll hit this limit, all they see is You can only post once every 60 minutes. I think it would be very appreciate to change / extend this message, adding You need to wait next xx minutes. I saw similar solutions on many forums.  Would it be hard to implement something like that?  EDIT: It could be either added as extension to above mentioned warning message or as red-colored reminder above Title field. Or even as an explanation message, preventing user from clicking on a Ask Question button? Anything would be good, to not let user write the question (can be time consuming) only to hit the wall of limit. This can be a little bit annoying or frustrating, don't you think?