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How to upgrade PostgreSQL from version 9.6 to version 10.1 without losing data?
...is the solution for Ubuntu users
First we have to stop postgresql
sudo /etc/init.d/postgresql stop
Create a new file called /etc/apt/sources.list.d/pgdg.list and add below line
deb http://apt.postgresql.org/pub/repos/apt/ utopic-pgdg main
Follow below commands
wget -q -O - https://www.postg...
Why is using the rails default_scope often recommend against?
... of default_scope is when you want something to be sorted: default_scope { order(:name) }.
– user2985898
Aug 25 '16 at 9:33
...
Rank items in an array using Python/NumPy, without sorting array twice
...
Use argsort twice, first to obtain the order of the array, then to obtain ranking:
array = numpy.array([4,2,7,1])
order = array.argsort()
ranks = order.argsort()
When dealing with 2D (or higher dimensional) arrays, be sure to pass an axis argument to argsort to...
How does RegexOptions.Compiled work?
...ases where you reuse the Regex object. However in some cases can be over 3 orders of magnitude slower to construct.
It also shows that the x64 version of .NET can be 5 to 6 times slower when it comes to compilation of regular expressions.
The recommendation would be to use the compiled version i...
How much of a git sha is *generally* considered necessary to uniquely identify a change in a given c
...s is still unique for a lot of them, but when we're talking about just two orders of magnitude difference between number of objects and the hash size, there will be collisions in truncated hash values.
It's no longer even close to unrealistic - it happens all the time.
We should both increase...
Why not inherit from List?
...of historical facts such as when a player was recruited, injured, retired, etc. Obviously the current player roster is an important fact that should probably be front-and-center, but there may be other interesting things you want to do with this object that require a more historical perspective.
...
How are zlib, gzip and zip related? What do they have in common and how are they different?
...A .tar file would have to be decompressed and scanned from start to end in order to build a directory, which is how a .tar file is listed.
Shortly after the introduction of gzip, around the mid-1990s, the same patent dispute called into question the free use of the .gif image format, very widely use...
What are the differences between git remote prune, git prune, git fetch --prune, etc
...oesn't affect your view of any branches.
git remote prune origin and git fetch --prune both operate on references under refs/remotes/... (I'll refer to these as remote references). It doesn't affect local branches. The git remote version is useful if you only want to remove remote references unde...
How to sort a list/tuple of lists/tuples by the element at a given index?
...
In order to sort a list of tuples (<word>, <count>), for count in descending order and word in alphabetical order:
data = [
('betty', 1),
('bought', 1),
('a', 1),
('bit', 1),
('of', 1),
('butter', 2),
('but', 1),
('...
What is the difference between JVM, JDK, JRE & OpenJDK?
... compiler (javac.exe), Java application launcher (java.exe), Appletviewer, etc…
Compiler converts java code into byte code. Java application launcher opens a JRE, loads the class, and invokes its main method.
You need JDK, if at all you want to write your own programs, and to compile them. For r...