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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

10 Tricky Apache-Storm Interview Questions

The storm is a real-time computation system. It is a flagship software from Apache foundation. Has the capability to process in-stream data. You can integrate traditional databases easily in the Storm. The tricky and highly useful interview questions given in this post for your quick reference. Bench mark for Storm is a million tuples processed per second per node.

Interview Questions

Tricky Interview Questions

1) Real uses of Storm?

A) You can use in real-time analytics, online machine learning, continuous computation, distributed RPC, ETL

2) What are different available layers on Storm?
  • Flux
  • SQL
  • Streams API
  • Trident 
3)  The real use of SQL API on top of Storm?

A) You can run SQL queries on stream data

4) Most popular integrations to Storm?
  1. HDFS
  2. Cassandra
  3. JDBC
  4. HIVE
  5. HBase
5) What are different possible Containers integration with Storm?
  1. YARN
  2. DOCKER
  3. MESOS
6) What is Local Mode?

A) Running topologies in the Local server we can say as Local Mode.

7) Where all the Events Stored in Storm?
A) Event Logger mechanism saves all events

8) What are Serializable data types in Storm?
A) Storm can serialize primitive types, strings, byte arrays, ArrayList, HashMap, and HashSet

9) What are Hooks in Storm?
A) You can place the custom code in Storm and you can run events many times

10) What is the Joining of Streams?
A) Streams from different sources you can Join on a particular join condition

References

Apache Spark Vs Apache Storm Vs Tableau

  • The storm is super past in stream processing engine for Big data analytics
  • Tableau is Data warehousing presentation tool
  • Spark is Cluster Maintenance and Fault Tolerance
Apache storm

  References

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