General

Steps to Optimize SQL Query Performance – Best Practices

We pay lots of attention to improve the performance of the web application, but ignore back-end SQL performance tuning. Even experts like application architects and the developer does not have an idea on how databases process the SQL queries internally. This could be because of lack of SQL and database knowledge. In this post, we will check best practices to optimize SQL query performance. How to Select SQL Query for Optimization? Identifying the query to optimize is a crucial step. Even today's most advance SQL engines require optimization. Simple SQL query tweak may increase the…

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January 9, 2019
Apache Spark

Spark SQL EXPLAIN Operator and Examples

Spark SQL uses Catalyst optimizer to create optimal execution plan. Execution plan will change based on scan, join operations, join order, type of joins, sub-queries and aggregate operations. In this article, we will check Spark SQL EXPLAIN Operator and some working examples. Spark SQL EXPLAIN Operator Spark SQL EXPLAIN operator provide detailed plan information about sql statement without actually running it. You can use the Spark SQL  EXPLAIN operator to display the actual execution plan that Spark execution engine will generates and uses while executing any query. You can use this execution plan…

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December 11, 2018
General

Quick and best way to Compare Two Tables in SQL

Say you have requirement to compare two tables. You have two tables in same database or server that you wish to compare, and check if any changes in the column values or see if any row is missing in either of tables. Below are some of the methods you can use to compare two tables in SQL. Compare Two Tables using UNION ALL UNION allows you to compare data from two similar tables or data sets. It also handles the NULL values to other NULL values which JOIN or WHERE…

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August 29, 2016