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Roland Mueller

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since Oct 28, 2011
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Recent posts by Roland Mueller

obaid abbassi wrote:  
still no out put from button two?

I had a typo in my first post messing up P and Q. My point is that btn1 or btn2 are null if there is no value coming from your client. There for an btn1.equals("<something>") will cause an exception.

In the following the values of btn1 and btn2 are first printed out. Then follow the null pointer-safe if statements.

6 days ago
you can use a check for null or turn around the participants in equals().
1 week ago
Just come to my mind: when btn1 has no value request.getParameter("btn1") should return null, and calling equals() on result should cause an null pointer exception. Thus, second check for btn2 is not reached.
1 week ago
I am not able to either reproduce or understand your problem: when clicking on button1 the page y gets value of button1 only. When clicking on button 2 only value of button 2 appears in y. Thus, it work's on my PC
1 week ago
Problem may be that the DOM is not ready when this code is executed. In plain JScript this code should be inside a handler called after html document has been loaded.

E.g. body element defines the onload handler that calls myFun.

<body onload="myFun()">

Tim Holloway wrote: Java, for example, requires a lot more time to be spent up front, less afterwards. Interpreted languages are generally quick to code, but more likely to blow up later in the lifecycle.Execution speed, however is another matter.

My point in the answer above is that Python packages do not necessarily only Python code. Instead Python often is only a binding layer around binary code written e.g. in C/C++. This is especially true for big data handling.

Thus, using a Python module for big data means that one is NOT using pure interpreted code or only Python.

Let's examine the content of python3-numpy rpm in my Fedora box: you can see a lot of shared objects (DLLs in Windows) included.

1 week ago
The workhorse for big data applications using Python is according to my knowledge not the Python bytecode rather than binary native libraries included in Python modules. This way I assume that performance difference should not be so dramatic.
2 weeks ago
MySQL bind string literals to an numeric index value. latter value is used for ordering the values.

Any additional information is a matter of the implementation. You as user should not care with it rather than just interacting with the SQL interface.

quarkus in my understanding is used to  compile java  to native code. This native binaries  cannot be integrated like JVM class or jar files.

Quarkus can also compiled to JVM class files but I think that is used only for verfication.
3 weeks ago

Alexander Green wrote:Thank you !
and how about if has composite index on A B but search only by B? Will the index likely be used?

No, that's conceptionally the same case as above where index was (A,B,C) and search uses (A,B). Sorry in my previous message I used subset instead of superset. I will correct that ASAP

Thus, the query search expression must include all parts of the index that may be used.

index (A,B,C) Search must be (A,B,C) + something in addition. E.g. query search (A,B,C,D) could be used but (A,B) not. Thus, query search must be a superset of the index.
The preferred way should be probably to have a REST API implemented in Spring and use React in combination with Redux on client side. Redux acts as an in-memory data storage that cab be queried by React components and updated from Javascript functions fetching data from Spring backend.

An example is HERE and the picture from the same site show the overall architecture of this approach.

Short answer is no.

If the search is not compatible with the index then the index will not be used.  The query must be based on a search that is a subset superset of the index expression thus (A,B,C) in your case.

There is a tool in PostgreSQL as other RDBMSs too named EXPLAIN for analyzing SQL queries. The usage of it is somehow different between Oracle DB, MySQL/MariaDb and PostgrSQL. Here is a link to a tutorial explaining 'explain'.

Basically, explain shows what the DB will do to resolve the query. Among other things it will show you the usage of indexes too.

In case you mean to render inside a web (=html) page you should have a look at the HTML element .
3 weeks ago
When the user is already authenticated by the middleware before reaching your code, you can get the user principle from request. And from Principle instance retrieve the user name.

3 weeks ago
In my understanding Selenium Webdriver can handle the starting of a download. Then the used browser will download the file and store it to disk.

Further handling of the file depends on the configuration in your operating system and how given file types are processed or read. This should be out of reach of Web client testing tools such as Selenium or Testcafe.

For doing more testing you may consider using Robot Framework that has broader testing functionality and is NOT restricted to the browser. Robot Framework may use Selenium through an adapter module and may do additional checks and actions with downloaded content.

Some article/tutorial:

Robot FW links:
1 month ago