Why did the desktop icon's link overlay change?

For a very long time desktop's way of indicating that a file is not on desktop but at some other location was by overlaying a simple arrow at the bottom of the desktop icon's bottom that you see on several items on this desktop image here:

Recently it has changed and here is how it looks now. There is a tiny image overlayed at the same location where the arrow from former times existed as shown.

The question is why?

This is a change driven by function, not just aesthetics.

Cloud services like OneDrive, Dropbox, and Google Drive needed a way to communicate the status of a file. Is it synced? Is it a local copy or a cloud-only file? Is it syncing right now?

The old arrow overlay didn't provide this information. To solve this, these services created their own icon overlays that appear on top of the standard file icon. The "folder-like" or other new icons you're seeing are probably one of these:

Details:

A folder or cloud symbol: Often indicates that the file is not a local copy, but an online-only file. This saves space on your hard drive. The symbol acts as both a shortcut indicator and a status indicator.

A green checkmark: Means the file is fully synced and up-to-date on both your computer and the cloud.

blue sync arrow: Indicates that the file is currently in the process of being synced.

A red "X" or exclamation point: Signals an error with syncing.

These overlays are a more modern, layered approach to icon design. They allow the operating system to show multiple pieces of information (is it a shortcut? what's its sync status?) in a small, visual format.

So, the change wasn't from a simple arrow to a simple folder. It was an evolution from a single-purpose icon (the arrow) to a more dynamic, multi-purpose one (the arrow plus a status icon). You'll still see the classic arrow on most shortcuts that are not managed by a cloud service.

This said, there are files that carry the arrow image overlay on their icons in the more recent desktop display shown above. Those items have no shortcut key as shown in their properties shown here:

How do I know a file exists (in R programming)?

If you access the help file on your computer on which you installed R then you can find the information at this link here:

http://127.0.0.1:12506/library/base/html/list.files.html

File information can be found here:
http://127.0.0.1:12506/library/base/html/file.info.html

I had a file names.csv (I had mistaken about its extension being .CSV, it was actually names.xls.csv) which I wanted to know if it exists. Then I used the following commands:

> file.exists("C:/")                Does C:\ folder exists (you should not use the backward slash)?
[1] TRUE

> file.exists("C:/eula.3082")  I know eula.3082 exists but... The reason is perhaps permissions
[1] FALSE

> file.exists("C:/inetpub")     Does C:\inetpub exist?
[1] TRUE

> file.exists("C:/USERS")       Does C:\Users exist?
[1] TRUE

> file.exists("C:/USERS/names.csv")  Does C:\Users\names.csv exist?
[1] FALSE
oops!
> file.exists("C:/USERS/JFA.jpg")       Does C\USERS/JFA.jpg exist?
[1] TRUE

I created a CSV file in EXCEL and made sure it was saved as a CSV by opening it in Notepad.

> file.exists("C:/USERS/mysorian/Documents/names2.csv")  Does C:\USERS\names2.csv?
[1] TRUE

> file.info("C:/USERS/mysorian/Documents/names2.csv")   Provide info on the file C:/USERS/mysorian/Documents/names2.csv
                                       size isdir mode               mtime               ctime
C:/USERS/mysorian/Documents/names2.csv   98 FALSE  666 2015-09-22 16:42:20 2015-09-22 16:42:20
                                                     atime exe
C:/USERS/mysorian/Documents/names2.csv 2015-09-22 16:42:20  no

Listing files in a directory

Also,  if you know the directory you can list all the files as in the following:
--------
Error: could not find function "List.files"  -- R language is case sensitive
> list.files("C:/USERS/mysorian/documents") List the files in the directory in quotes

  [1] "__VSDeploymentFailure__.txt"                     
  [2] "~$ADI_gREETINGS.dotx"                            
  [3] "~$TrustRelated.xlsx"                             
  [4] "04092013 ConsolidatedDetails.xls"                
  [5] "3rd beneficiary details_sept15_2014.dotx"        
  [6] "4mysorian.xlsx"                                  
  [7] "Advanced SQL TOP.dot"                            
  [8] "AdvisoryMichiko.xlsx"                            
  [9] "AdvWksCustomer.rdl"                              
 [10] "Allow connections to this computer.pdf"          
 [11] "Ameritrade2014.csv"                              
 [12] "ApnStub.exe"                                     
 [13] "ArcGIS Explorer"  

What is Polybase?

It is a Microsoft Data tool. It simplifies management of relational and non-relational data with the ability to query both.

You want to query non-relational data. Do you modify it and bring it into SQL Server which is relational and then query it? Or do you buy another product to query non-relational data (like data in Hadoop, blobs and files)?

Well Polybase provides the capability to query non-relational data in-situ using the SQL Server using T-SQL. You need not move the data over to SQL Server although SQL Server gives the option to store in SQL Server if you want to do so. Polybase is supported out of the box in SQL Server 2016 CTP2 which means it will be available in SQL Server 2016.

Polybase was not supported out of the box in earlier version. Of course Polybase can process the queries whether it is on the premises or in the cloud.

Here is a rough schematic of what it is about.