Use Indexes
Efficiently designed and consistently managed indexes can notably enhance query performance, enabling the database to swiftly locate and fetch data.
Use Limit to retrieve data
Opt for selecting only essential columns with ‘SELECT’ rather than ‘SELECT *’ to minimize unnecessary data transfer and processing overhead.
Avoid Sub Queries in WHERE clause
Subqueries, especially when returning a substantial number of rows, can be resource-intensive and complex to execute. Consider utilizing join operations or crafting a correlated subquery to achieve equivalent results, thereby optimizing performance.
Steer clear of combining DISTINCT and GROUP BY in queries.
Using GROUP BY inherently ensures row distinctness, rendering the use of DISTINCT alongside GROUP BY redundant.
Replace UNION with UNION ALL
For improved UNION operations, consider utilizing UNION ALL over UNION when duplicate elimination is unnecessary or can be managed post-operation. Reserve the use of DISTINCT for essential cases, as it entails additional sorting and row comparison processes.
Avoid using UNION and DISTINCT at the same time
UNION inherently ensures distinct records, obviating the need for using DISTINCT alongside UNION.