Ruby on Rails Developer

Monday, 26 March 2018

truncate word with screen resolution

.wrap{
white-space: nowrap;
overflow: hidden;
text-overflow: ellipsis;
max-width: 100%;
}

Check Query Execution Time in spark

def time[A](f: => A) = {

val s = System.nanoTime

val ret = f

println("time: " + (System.nanoTime - s) / 1e9 + " seconds")

ret

}

val test = time('statement')

val test = time(spark.sql("SELECT * from mmc_push_event.push_devices"))

Friday, 23 March 2018

Install Cassandra in ubuntu and CentOS

Cassandra requires that the Oracle Java SE Runtime Environment (JRE) be installed.
So, in this step, you'll install and verify that it's the default JRE.


sudo add-apt-repository ppa:webupd8team/java


sudo apt-get update


sudo apt-get install oracle-java8-set-default


java -version

You should see output similar to the following:


Output
java version "1.8.0_60"
Java(TM) SE Runtime Environment (build 1.8.0_60-b27)
Java HotSpot(TM) 64-Bit Server VM (build 25.60-b23, mixed mode)

Installing Cassandra

Note that Cassandra 2.2.2 is the latest version at the time of this publication. Change the 22x to match the latest version. For example, use 23x if Cassandra 2.3 is the latest version:


echo "deb http://www.apache.org/dist/cassandra/debian 22x main" | sudo tee -a /etc/apt/sources.list.d/cassandra.sources.list

The add the repo's source:


echo "deb-src http://www.apache.org/dist/cassandra/debian 22x main" | sudo tee -a /etc/apt/sources.list.d/cassandra.sources.list

To avoid package signature warnings during package updates, we need to add three public keys from the Apache Software Foundation associated with the package repositories.

Add the first one using this pair of commands, which must be run one after the other:


gpg --keyserver pgp.mit.edu --recv-keys F758CE318D77295D

gpg --export --armor F758CE318D77295D | sudo apt-key add -

Then add the second key:


gpg --keyserver pgp.mit.edu --recv-keys 2B5C1B00

gpg --export --armor 2B5C1B00 | sudo apt-key add -

Then add the third:


gpg --keyserver pgp.mit.edu --recv-keys 0353B12C

gpg --export --armor 0353B12C | sudo apt-key add -

Update the package database once again:


sudo apt-get update

Finally, install Cassandra:


sudo apt-get install cassandra

Cassandra should have been started automatically at this point. However, because of a bug, it does not. To confirm that it's not running, type:


sudo service cassandra status

If it is not running, the following output will be displayed:


Output
* could not access pidfile for Cassandra

This is a well-known issue with the latest versions of Cassandra on Ubuntu. We'll try a few fixes. First, start by editing its init script. The parameter we're going to modify is on line 60 of that script, so open it using:


sudo nano +60 /etc/init.d/cassandra


/etc/init.d/cassandra
CMD_PATT="cassandra.+CassandraDaemon"

Change it to:


/etc/init.d/cassandra
CMD_PATT="cassandra"

Close and save the file, then reboot the server:


sudo reboot

Or:


sudo shutdown -r now

After logging back in, Cassandra should now be running. Verify:


sudo service cassandra status

If you are successful, you will see:


Output
* Cassandra is running

Connecting to the Cluster


sudo nodetool status

In the output, UN means it's Up and Normal:


Output
Datacenter: datacenter1
=======================
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving
--  Address    Load       Tokens       Owns    Host ID                               Rack
UN  127.0.0.1  142.02 KB  256          ?       2053956d-7461-41e6-8dd2-0af59436f736  rack1

Note: Non-system keyspaces don't have the same replication settings, effective ownership information is meaningless

Then connect to it using its interactive command line interface cqlsh.


cqlsh

You will see it connect:


Output
Connected to Test Cluster at 127.0.0.1:9042.
[cqlsh 5.0.1 | Cassandra 2.2.2 | CQL spec 3.3.1 | Native protocol v4]
Use HELP for help.
cqlsh>

Type exit to quit:

Method - 2 Install Cassandra on CentOS 7

yum -y update

yum -y install java

vim /etc/yum.repos.d/datastax.repo

- copy and paste this code to

[datastax]

name = DataStax Repo for Apache Cassandra

baseurl = http://rpm.datastax.com/community

enabled = 1

gpgcheck = 0

:wq

yum -y install dsc20

Start-Up Cassandra

systemctl start cassandra

Method-1 Try this method first if this will not working use method 2 which is given below

""connect cassandra to cqlsh""

----------xXx------------

Check Cassandra Service Status

systemctl status cassandra

Enable Cassandra to Start at Boot

systemctl enable cassandra

-----------xXx----------------

Method-2

""connect cassandra to cqlsh""

- sudo service cassandra start

after that type

cqlsh 127.0.0.1 or cqlsh

Wednesday, 14 March 2018

arel table Methods

http://www.rubydoc.info/github/rails/arel/master/Arel/Predications#does_not_match-instance_method

Monday, 12 March 2018

Generate Custom string

small_rand = [*('a'..'z')].shuffle

number_rand = [*('0'..'9')].shuffle

cap_rand = [*('A'..'Z')].shuffle

password_rand = small_rand[0..1].join + number_rand[0..6].join + cap_rand[0]

Sunday, 11 March 2018

testing configration in application.rb

config.generators do |g|
  g.test_framework :rspec,
    :fixtures => true,
    :view_specs => false,
    :helper_specs => false,
    :routing_specs => false,
    :controller_specs => true,
    :request_specs => true
  g.fixture_replacement :factory_girl, :dir => "spec/factories"
end

Sunday, 18 February 2018

FInd months and weeks between two date range OR Add array index to each other

require 'date'

months = (Date.parse("2014-01-30")..Date.parse("2014-03-27")).group_by(&:month).map { |_,v| v.first.end_of_month.to_s }

# => ["2014-01-31", "2014-02-28", "2014-03-31"]

weeks = (Date.parse("2014-01-30")..Date.parse("2014-03-27")).select(&:sunday?).map(&:to_s)

Add Array index with Value

[[1,2,3], [4,5,6]].transpose.map {|x| x.reduce(:+)}