magento2.3 – Magento2 Technical Question – Observer Implementation

Hello Magento Experts,

I was just wondering about the question below for observer implementation –

Question :

In a code review of a merchant site you have discovered that there are multiple observers for
the checkout_submit_all_after event. After closer inspection, you notice one of these observers is
relying on the others being executed before it is called.
What risk does this pose, and how can it be mitigated?

Options :

A. There is no risk posed as long as each event observer specifies a correct sortOrder. Nothing needs
to be changed.
B. Event observers are fired in alphabetical order of the observer name. There is no risk here.
C. Magento only supports one observer per event. These observers will need to be combined into a
single point of customization.
D. Order of listener execution cannot be guaranteed, resulting in a fragile implementation. This code
should be re-worked using plugins

I think the answer should be “B” because if there are multiple observers, all method should work in alphabetical order.

Can someone let me know about it.

Thank you

A question on Grothendieck space

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geometry – how to slove the question about cirumcentre? sorry for my language

Let P be a moving point. G is the circumcentre of trianglePQR. The coordinates of Q, R and G are (6,9),(a,11) and (h,3)respectively,where h > 0.

question(a): how to express the coordinate of G in terms of a ?

question(b): It is give that the slope of RG is 4/3(4 over 3). Denote the circumscribed circle of trianglePQR by C.A straight line L: y=kx cuts C at two distinct points S and T, where k>0.M is the mid-point of ST.

     (bi): Find a

     (bii) Show that the x-coordinate of M is 14+3k/1+k^2 (14+3k over 1+k^2) 

     (biii) The shortest distance from the origin O to the line passing through G and M is 2 times 
            square root 41.Denote the location of P by a point A when P is farthest from M, and 
            denote the location of P by a point B when P is nearest to the y-axis.If U is a point 
            below the x-axis such that the area of the circle passing through A, B and U is the 
            least, are A,M,B and U concyclic?

Thank for reading

SQL Server & Storage Question – What’s the right choice?

I am a young DBA from Germany and I am the administrator for our customers SQL Servers.

I have a question and I really hope that I can explain this in English words. 😃

At the moment I am reading Breant Ozwar’s eBook SQL Server Setup Checklist and there is one thing that I am confused about.
I mean this one:

2.5.Provision storage for the OS and for SQL Server We don’t want to pile everything on the C drive, so create other volumes for SQL Server to spread across. Ideally, we’ll have separate logical drives for:
• SQL Server application folders – D:

• SQL Server databases data files – G:

• SQL Server database log files (including TempDB) – L:

• TempDB data file(s) – T:

• Backups – H:

I’ve learned /and it’s an advice from Microsoft two) to use separate drives for DB, Logs etc.
BUT I’m asking myself if this makes only sense when we have a physical server with e.g 5 drives, because every disk has different IOPS.

But when the Server got disks from a big storage (that’s managed by a Storage Controller) do we really need different disks for DB, Log etc.?
I mean the Storage Controller controls the IOPS. So if you have one drive and put DB, Log etc. just in different folders then they got the same IOPS when they are on different disks. Or is this wrong?

I hope you understand what I mean.
But the main question is: Does is make sense to put DB, Log, Temp on different drives when the Server get his drives from a Storage? Or does it make only sense when we have a physical server with physical disks?

Hopefully you can help me with this one, because I am not sure how to configure future Cluster systems (we don’t have much hardware servers).

Thanks in advance for reply and I hope your your doing all good.

Melissa

motorola – Smartphones brands with stylus questions carriers misc question

What phone is better the lg stylo 6 or the moto stylus or the galaxy note 8, 9, 10

Is their better phones with styluses

Is their more lg stylo brands 5 6 7 8 etc.

Are the galaxy notes.good phones

What service provider can you get galaxy note phones besides 20 amd 10 9 8 7 6 any of these

How much is it for unlimited with certain providers can you get the note phones for metro can you use a note 10 from.tmobile with metro.does it.use a sim card
Also who is the best
Atat
Verizion
Tmobile sprint
Boost
Am I missing any others besides cricket and metro

Question about derivative of scalar function of matrix wrt scalar

Can someone help me understand the meaning of this derivative where i have a scalar, wich is a function of a matrix, when i take it with respect to another scalar?
begin{align}
y = mathrm{ln}|At+B|,
end{align}

where $A$ and $B$ are matrices, $B$ is invertible, $t$ and $y$ are scalars.

With $X = At+B$ the function become
begin{align}
y = mathrm{ln}|X|.
end{align}

The differentials are
begin{align}
dy
&= d mathrm{ln}|X|cr
&= mathrm{Tr}(X^{-1} dX)cr
&= X^{-T}:dXcr
dX &= (dAt+Adt+dB).
end{align}

Since i only ask about $t implies dX = Adt$. Substituting $dX$ in $dy$ led to
begin{align}
dy
&= X^{-T}:dXcr
&= X^{-T}:Adtcr
&= A^TX^{-T}:dt.cr
end{align}

Therefore the gradient is
begin{align}
frac{dy}{dt}
&= A^TX^{-T}cr
&= A^T(At+B)^{-T},cr
end{align}

where the answer is an matrix for any $t$.
I was expecting a scalar as a result.

How this answer can be interpreted? There is something wrong with my development?

Any help would be appreciated.

characteristic functions – partial differential equations question

Im trying to solve a question using the method of characteristics. The PDE in question is:

My characteristic equation is: x=$C_2$*e^(2tT), $t=xT+C_1$, $u=C_3$*e^(2tT) where T is tau. (sorry latex is not a strong point here)

i then parametrised the intial conditions with x=s, t=0, u=s^3 on T=0.

The values i got are $C_1=0$, $C_2=s$ and $C_3=s^3$. im just wondering if these values are correct or not. Thanks