prompt less installing mariadb-server-5.5 on ubuntu

You need to previously set the root password

echo mariadb-server-5.5 mysql-server/root_password password xxxxx | sudo debconf-set-selections
echo mariadb-server-5.5 mysql-server/root_password_again password xxxxx | sudo debconf-set-selections

And then

sudo apt-get -y install mariadb-server

If you are going to uninstall mariadb totally, you may

sudo apt-get purge mariadb* && sudo apt-get autoremove

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A simple implementation of DTW(Dynamic Time Warping) in C#/python

DTW(Dynamic Time Warping) is a very useful tools for time series analysis. This is a very simple (but not very efficient) c# implementation of DTW, the source code is available at https://gist.github.com/1966342 . Use the program as below: double[] x = {9,3,1,5,1,2,0,1,0,2,2,8,1,7,0,6,4,4,5}; double[] y = {1,0,5,5,0,1,0,1,0,3,3,2,8,1,0,6,4,4,5}; SimpleDTW dtw = new SimpleDTW(x,y); dtw.calculateDTW(); The python implementation is available at https://gist.github.com/3265694 . from python-dtw import Dtw import math dtw = Dtw([1, 2, 3, 4, 6], [1, 2, 3, 5], distance_func=lambda x, y: math.fabs(x - y)) print dtw.calculate() #calculate the distance print dtw.get_path() #calculate the mapping path

Change the default user when start a docker container

When run(start) a docker container from an image, we can specify the default user by passing -u option in command line(In https://docs.docker.com/engine/reference/run/#user ). For example docker run -i -t -u ubuntu ubuntu:latest /bin/bash We can also use the USER instruction in DOCKERFILE to do the same thing(In https://docs.docker.com/engine/reference/builder/#user), note that the option in command line will override the one in the DOCKERFILE. And there is actually another way to start a container with neither DOCKERFILE nor -u option, just by a command like: docker run -i -t ubuntu:latest /bin/bash # with ubuntu as the default user This happens when your start the container from an image committed by a container with ubuntu as the default user. Or in detail: Run a container from some basic images, create ubuntu user inside it, commit the container to CUSTOM_IMAGE:1 . Run a container from CUSTOM_IMAGE:1 with "-u ubuntu" option, and commit the container to CUSTOM

The default CREATE TABLE options for Aria Engine in mariadb

The official document of mariadb does not mention the default CREATE TABLE options for tables using Aria Engine. The default options are list as below: TRANSACTIONAL, the default value is TRANSACTIONAL=0, i.e., non-transactional. ROW_FORMAT, the default value is ROW_FORMAT=PAGE, which may suits both transactional and non-transactional tables. PAGE_CHECKSUM, the default value will follow aria_page_checksum system variable, which has default value ON. For the TRANSACTIONAL option, you may consider create a table as below(and ALTER the TRANSACTIONAL=1): CREATE TABLE `test_table` ( `id` int(11) NOT NULL AUTO_INCREMENT, PRIMARY KEY (`id`) ) ENGINE=Aria; If you change the ROW_FORMAT to DYNAMIC or FIXED, everything just goes fine. But if you have ALTER the table with TRANSACTION=1 and change the ROW_FORMAT to DYNAMIC or FIXED, you may got a warning: SHOW WARNINGS; +-------+------+----------------------------------------------------------+ | Level | Code | Message | +-------+--

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