thanoojgithub

Spring Boot Notes

@Component vs @Bean

The @Bean annotation is a method-level annotation, whereas @Component is a class-level annotation.

The @Component annotation doesn't need to be used with the @Configuration annotation, whereas the @Bean generic annotation has to be used within a class annotated with @Configuration.


If your component doesn't need to communicate with a database or return an HTTP result, you can use the @Service annotation whenever using the @Component annotation is possible.

thanoojgithub

MySQL installation in ubuntu 
sudo apt update
sudo apt upgrade
sudo apt install mysql-server
sudo apt install mysql-client
mysql --version

sudo usermod -d /var/lib/mysql/ mysql
sudo service mysql start
sudo service mysql status

thanoojgithub

thanooj@thanoojWin10Home:~$ sudo apt update
thanooj@thanoojWin10Home:~$ sudo apt upgrade
thanooj@thanoojWin10Home:~$ sudo apt autoremove
thanooj@thanoojWin10Home:~$ sudo apt install redis-server


sudo service redis-server start
or

thanoojgithub

Hadoop 3.2.2
Start-up commands:
--------------------------------
1. Stop the dfs and yarn first.
2. Remove the datanode and namenode directories as specified in the core-site.xml file.
3. Re-create the directories.
4. hdfs namenode -format
5. Then re-start the dfs and the yarn as follows.
start-dfs.sh
start-yarn.sh

thanoojgithub

MySQL Shell 8.0.28

Copyright (c) 2016, 2022, Oracle and/or its affiliates.
Oracle is a registered trademark of Oracle Corporation and/or its affiliates.
Other names may be trademarks of their respective owners.

Type '\help' or '\?' for help; '\quit' to exit.
 MySQL  JS > \connect thanooj@localhost
Creating a session to 'thanooj@localhost'
Please provide the password for 'thanooj@localhost': ********

thanoojgithub

from pyspark.sql import SparkSession
from pyspark.sql.functions import *

from pyspark.sql.types import StructType, StructField, StringType, TimestampType

if __name__ == "__main__":
    spark = SparkSession \
        .builder \
        .master('local') \
        .appName('pyspark-test-run') \

thanoojgithub

from pyspark.sql import SparkSession
from pyspark.sql.functions import *

spark = SparkSession \
    .builder \
    .master('local') \
    .appName('pyspark-test-run') \
    .getOrCreate()
spark.sparkContext.setLogLevel("ERROR")

thanoojgithub

from pyspark.sql import SparkSession
from pyspark.sql.functions import *

spark = SparkSession \
    .builder \
    .master('local') \
    .appName('pyspark-test-run') \
    .getOrCreate()
spark.sparkContext.setLogLevel("ERROR")

thanoojgithub

from pyspark.sql import SparkSession
from pyspark.sql import Window
from pyspark.sql.functions import *

spark = SparkSession \
    .builder \
    .master('local') \
    .appName('pyspark-test-run') \
    .getOrCreate()

thanoojgithub

1. How to find out second hightest value from a Map<String, Integer>
	Map<String, Integer> books = new HashMap<>();
	books.put("one", 1);
	books.put("two", 22);
	books.put("three", 333);
	books.put("four", 4444);
	books.put("five", 55555);
	books.put("six", 666666);
	Stream<Integer> list = books.entrySet().stream().filter(e -> e.getValue().toString().length() > 3)
				.map(Map.Entry::getValue);