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SQL Query: 3 Methods for Calculating Cumulative SUM

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SQL provides various constructs for calculating cumulative sums, offering flexibility and efficiency in data analysis. In this article, we explore three distinct SQL queries that facilitate the computation of cumulative sums. Each query leverages different SQL constructs to achieve the desired outcome, catering to diverse analytical needs and preferences. Using Window Functions (e.g., PostgreSQL, SQL Server, Oracle) SELECT id, value, SUM(value) OVER (ORDER BY id) AS cumulative_sum  FROM your_table; This query uses the SUM() window function with the OVER clause to calculate the cumulative sum of the value column ordered by the id column. Using Subqueries (e.g., MySQL, SQLite): SELECT t1.id, t1.value, SUM(t2.value) AS cumulative_sum FROM your_table t1 JOIN your_table t2 ON t1.id >= t2.id GROUP BY t1.id, t1.value ORDER BY t1.id; This query uses a self-join to calculate the cumulative sum. It joins the table with itself, matching rows where the id in the first table is greater than or

2 Exclusive Ways to Start Kafka Services

The Kafka services start or stop you can do in two ways. Those are Systemd and Systemctl (sudo user). Below, you will find the commands for these two methods.


2 Ways to start Kafka Services


How to start/stop Kafka service

Here are exclusive ways. With these, you can start or stop Kafka services.  

1. Systemd service

The concept of unit files people who worked on Linux servers have familiarity with it. Also, they know creating the unit file to use by systemd.

To summarize, it initializes and maintains components throughout the system. This means that you can define ZooKeeper and Kafka as unit files, which then will be used by systems.


Commands

The first command starts the service, and the second command stops the service.

... [Service] ...

ExecStart=/opt/kafkainaction/bin/zookeeper-server-start.sh
ExecStop= /opt/kafkainaction/bin/zookeeper-server-stop.sh


2. Systemctl by Sudo (root) user

The root user can start or stop the Kafka services. This is more like front-end processing. This way of executing is called systemctl.

Commands

The first command starts the Zookeeper and the second one starts Kafka.

$sudo systemctl start zookeeper
$sudo systemctl start kafka

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