Oracle DB not generating AWR

Sysaux tablespace is almost full . Could this be the reason AWR snapshot is not generated ? Although I do have the AutoExtend ON for SYSAUX tablespace.

pseudo random generators – Is it possible to get the true generating function of a PRNG?

Since every sequence of pseudo-random numbers must be generated by deterministic means, it has to follow some underlying mathematical expression (function-like I guess). Suposse you intend to get this underlying expression in order to predict the output of the PRNG. Even if you could predict the next pseudo-random number that the expression will generate every single time for a billion iterations (say $n$), you could never be sure that the process will not backfire at any given moment, as a consequence of the underlying expression being defined by some piecewise function of the kind:

$$forall x ; g(x)=delta$$

$$g^{prime}(x)=left{begin{array}{ll}delta & text { if } x<n \ delta^{prime} & text { if } x geq nend{array}right.$$

Where $delta$ and $delta’$ are distinct mathematical expressions as a function of $x$ and n is an arbitrarily large threshold. I have to attempt such a feat (predicting the next random number that a PRNG will output) with machine learning tools, and this observation, although perhaps of triviality, may be of importance, at least to clear out that I will not be able to find any definite solutions to the task, only partial and working solutions.

My issue is that I lack solid or even basic knowledge of the fundamentals of mathematical proving, and I am not even sure if the above counts as a rigurous proof, or if there is a way to formally express the thought. My inquiry would be to know if I am mistaken in my assessment and, otherwise, to obtain a formal proof to include this in my work in a respectable manner. Any thoughts and remarks are welcomed.

table – Generating a list of two-dim. points from list of higher-dim. ones

I have a table of lists, ie. s = { {1, 2, 4}, {7, 11}, {3, 4, 12} }. From this table, I would like to create the table of points { {1,1} , {1,2} , {1,4} , {2,7} , {2,11} , {3,3} , {3, 4} , {3, 12} } where for each element $k$ of the $i$-th part of s, the point {i,k} is contained in the new table.

How can I do this? I am not experienced with Mathematica and only know how to use Table, Select, Part, etc. But those do not seem to work here.

Note: these were only examples; my actual s is much larger, so doing this manually is right out.

seo – Generating URLs according to the search engine query

What is the name of following technique:

When you search a multi word keyword, for example “download physics book edition 218324”, the search engine finds a page from a website with exactly same parameters like:

example.com/whatever/download-physics-book-edition-218324

Now because this is a very very specific query with a very specific number, it is sure that the page does not actually exist on that website, but it is generated dynamically according to that query. When you click on the above URL, it can lead to the search page of that website where that query has been copied.

What is name of this technique/method? and how is this done?

domain driven design – Serialization in REST API: Generating Representations Based on a Model

I am developing a RESTful API using .NET technology to implement the service.

The part that I am having problems with is the dynamic nature of the representation types that the service will return.

For example, let’s say I have a Person model, and the Person has a bunch of Beyblades toys they can battle other people with.

My model would look something like:

public class Person{
  public guid ID {get; set;}
  public string Name {get; set;}
  public List<Beyblades> Beyblades{get; set;}
  //...
}

The API will return a list of People by going to “urlpeople”. The representation for the people returned will contain the person’s ID, name, and a link to “urlbeybladesperson-ID” that can be followed instead of the serialized list of their Beyblades (if they have any).

Seems pretty straightforward, but the implementation of a dynamically generating links for lists-of-things (and not the list’s themselves) is what I’m trying to find the best solution for.

My initial thought was to create templates for the representations returned. The template would check the model in order to output the correct representation data. For example, the template would check if the person has any Beyblades, and if so it would generate the link (instead of the serialized list of Beyblade models); likewise, it would generate a self link for each person as well.

The problem with this solution is that if my API is to support JSON (Hal), XML, and say HTML as possible representation output types, I would have to manage at least 3 templates whenever something in the model were changed.

My next thought is to design a serialization framework by implementing a series of MediaTypeFormatter types that would naturally consider my business logic to convert lists into appropriate links; however, this too could become problematic while maintaining the API since there would have to be some sort of standard mapping between lists of things and API URLs and this may not be apparent when changes are made.

Since REST is not a new thing, I was wondering if there .NET already has tools for serializing models into a RESTful representations?

Or if there was a best practices document/tutorial on this topic?

Or maybe I’m conceptually going about this wrong and someone here could point me in the right direction?

I realize that REST and OO doesn’t seem go hand-in-hand, so maybe there isn’t anything like what I am seeking. It just feels like I’m inventing a wheel that someone has probably already done.

random – Randomly generating invoice IDs

As more fully detailed in my question here, I’m in the process of starting a small, local business and wanted to avoid showing sequential invoice IDs to clients, and instead generate completely random ones. Thanks to the advice in the comments to that question, I decided to eliminate the risk of any collisions by incorporating logic that checks against a database (a flat text file) of all IDs that have previously been generated.

This is my attempt at doing so, which to my amazement is functional, but probably not as robust as it could be. Since then I have also decided on using 5-digit numbers, as these look better to me and a limit of 99,000 transactions (without 00000, and I might even exclude the first 10,000 digits through to 09999) will be more than enough for me, and the logic of the script means that collisions should no longer be an issue.

#!/usr/bin/env bash

generate_num() {
num=$(head /dev/urandom | tr -dc '(:digit:)' | cut -c 1-5)
}

read -p "Are you sure you want to generate a new invoice ID? (Y/n) " -n 1 -r
echo
if (( $REPLY =~ ^(Yy)$ ))
then
    generate_num && echo Generating a random invoice ID and checking against database...
    sleep 2

    while grep -xq "$num" "ID_database" 
        do
            echo Invoice ID #$num already exists in database...
            sleep 2
            generate_num && echo Generating new random invoice ID and checking against database...
            sleep 2
        done

    echo Generated random invoice ID #$num
    sleep 1
    echo Invoice ID #$num does not exist in database...
    sleep 2
    echo $num >> "ID_database" && echo Successfully added Invoice ID #$num to database...
fi

I have two main questions I’d like answered about it.

  1. Can the code itself be improved on? This is one of the few Bash scripts I’ve ever written the core logic for, and perhaps the most involved, so if there’s anything I shouldn’t be doing or anything I could do better, I’d appreciate this.

  2. Would it be conceivable to move the “database” into the script file itself, thus avoiding the need to maintain two separate files? If not, what are the reasons for this?

Thank you in advance, I’d appreciate some help from those more experienced with Bash than I am.

Trouble generating a p12 certificate for wallet signing

I’ve been trying to replace an expired p12 certificate which is used for signing AppleWallet passes in PHP.

The problem I’m having is nothing to do with the PHP end of things but getting and exporting the certificates as P12.

Here are the steps I have taken, along with the original url for the instructions for each step

  1. create a csr (see https://help.apple.com/developer-account/#/devbfa00fef7)
  • Launch Keychain Access located in /Applications/Utilities.

  • Choose Keychain Access > Certificate Assistant > Request a Certificate from a Certificate Authority.

  • In the Certificate Assistant dialog, enter an email address in the User Email Address field.

  • In the Common Name field, enter a name for the key (for example, Gita Kumar Dev Key).

  • Leave the CA Email Address field empty.

  • Choose “Saved to disk”, and click Continue.

  1. Go to Apple Developer portal and under Certificates, Identifiers & Profiles create an Identifier
  • In Certificates, Identifiers & Profiles, select Identifiers.

  • Under Identifiers, select Pass Type IDs.

  • Click the plus (+) button.

  • Enter the description and pass type identifier, and click Submit.

note: I first tried the existing identifier from the previous certificate. That didn’t work so I deleted it and created a new one.

  1. Create the Certificate
    (see https://developer.apple.com/library/archive/documentation/UserExperience/Conceptual/PassKit_PG/YourFirst.html)
  • In Certificates, Identifiers & Profiles, select Identifiers.

  • Under Identifiers, select Pass Type IDs.

  • Select the pass type identifier, then click Edit.

  • click the Create Certificate button, then follow the instructions to create a pass signing certificate.

  1. Download that certificate and the double click it to import into my Key Chain

When I import it, it appears as just a single certificate and not a group like the previous one, so I cannot then export it as a .p12. See attached screen shot where top cert is the new single cert and second cert is the expired group of certs.screenshot

Where am I going wrong that the imported certificate does not contain the self signed certificate that I uploaded as part of the creation in step 3)

  • I have tried using variations of different common names and leaving the cert name blank in step 3?

Another thing I noticed in Keychain Access is that the new cert doesn’t appear under the “My Certificates” group, only under the “Certificates” group, so it almost looks like my identity is screwed. I did just upgrade to Catalina!

generating a private key for a blockchain wallet

I hired a broker to make forex and crypto profits for me. They did and put it in my broker account. the only method to get the profit out was to put it in a blockchain wallet. After they did this, they told me to get the private key from them to withdraw the profit was to pay a very expensive fee. I do not have that money at the present time or in the near future. Is there an easy way to generate my own private key from my blockchain app on my Samsung to withdraw the money and put it in my bank account? I feel it is my bitcoin, why can’t I withdraw it without buying a private key from them? I would like to have someone
walk me through a simple process to generate my own private key. I read online that if you do not do it right, you can lose that bitcoin forever. I don’t want to do that. Let me know if you can help me with this problem. Thanks.

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web development – How do I organize my REST API codes along with the codes for generating the website?

Using github as an example, www.github.com is the website people visit and api.github.com is the REST api server programs will visit. But they probably share some codebase and in my case they share a lot.

We actually developed the rest server first for our mobile apps then we decided to develop a website because we had though there were quite some codes can be reused. But now codes are not clean at all and I am trying to refactor them.

The similarity between them and the problems I need to fix include:

First, the logic to access the database is basically the same. After get the data, the REST codes will just return them as JSON while the “website code” (without a better word to describe them) will feed the data to the template which then generates the html pages.

Second, the router logics share in common a lot.

Third, I need to make the deployment easy. We use nginx to direct REST request to the rest server and website request (again, without a better word) to the website server, which is different from the rest server(2 standalone servers).

So how do I organize the source codes to be DRY & be easy deployment ?