What is database schema?

As is known, database schema is a collection of database rules like data type and data relationship. However, this is still a little abstract. So what is database schema in one sentence everyone could understand it clearly. The wikipedia page on Database schema is quite good for understanding the concept. A database schema of a…

How to remove AdSense ads for mobile devices while keep them for desktops?

I want to add adsense ads to be shown to visitors on desktop only. How to remove AdSense ads for mobile devices? You can achieve this through using “Responsive ad unit” of AdSense. The support article Create a responsive ad unit from AdSense discusses this and gives an example. Check the “Hiding an ad unit”…

How to make taglist recognize specific files with certain extensions as C source files?

How to make taglist recognize specific files with certain extensions as C source files? You may try adding this line to your ~/.vimrc: autocmd BufRead,BufNewFile *.c0 set filetype=c Reference: https://stackoverflow.com/questions/9013263/vim-tagslist-plugin-not-detecting-custom-language-racket

How to add a new HDFS NameNode metadata directory to an existing cluster?

We have a running HDFS cluster. Currently, the NameNode metadata data directory has only one directory configured in hdfs-site.xml: <property> <name>dfs.namenode.name.dir</name> <value>file:///home/hadoop/hdfs/</value> <description>NameNode directory for namespace and transaction logs storage.</description> </property> We would like to add a new directory for dfs.namenode.name.dir to make replicas of the metadata on a separated disk for higher data reliability….

How to suppress “Entering/Leaving…” messages when invoking make recursively?

The “Entering/Leaving…” messages when invoking another make by a make is kind of annoying. Is it possible to suppress these messages and how to suppress them? For GNU make, it is controlled by options: -w, –print-directory Print a message containing the working directory before and after other processing. This may be useful for tracking down…