Benefits of Indexing
Indexing in SQL table is a database arrangement or database table information optimization management process. Which helps the user in fast access and retrieval by properly indexing the database table data and information in the secondary storage location, which takes less time on data table data modification operation. In SQL, the index in the database is a data storage structure order. Whatever data and information is stored in the SQL database table. It is indexed and accessed and displayed fast as per the need of the database user. By database table indexing, the required data rows and columns can be searched and previewed immediately according to the database query criteria.
The main benefits of indexing in SQL table are as follows.
Query performance (read operation) in fast SQL table.
The most important advantage of indexing in SQL table is fast data table query performance improvement. Indexing improves and speeds up the existing database data processing retrieval operation. Special search criteria allow immediate retrieval of data for SELECT queries with multiple clauses such as WHERE, JOIN, ORDER BY and GROUP BY clauses.
- Faster Searching – Without indexing in SQL database tables, existing databases would have to manually scan the complete table, checking individual rows one by one for matching search terms to match the query condition. With indexing features, the search query can move directly from the database to the query data, allowing you to retrieve only the required search term.
- Efficient Sorting – Indexing in SQL tables allows data to be sorted and arranged quickly, especially when the query uses ORDER BY clause. If indexed columns are used for sorting in SQL tables, the database can perform sort operations on the entire dataset and extract only the information needed by optimizing the database query.
Example in SQL table.
In a large database table, there is a table like employeee table with a lot of data, and you frequently query based on employee_id. Where indexing on employee_id allows the query to quickly find the desired rows from the search query without scanning the whole table.
SELECT * FROM employe WHERE employee_id = 1001;
Here without indexing, this query will manually scan all the rows in the employeee table. While with indexing, it directly searches and displays the rows from employee_id = 1001.
Improved performance for joins in SQL tables.
Indexing join tables in SQL database tables can greatly simplify the performance of database operations by improving fast storage access and retrieval processes, especially when you are dealing with a large database table.
- Optimized joins in SQL tables – When joining between tables on indexed table columns in a SQL database table, the database uses indexing to find matching rows more efficiently, instead of fully scanning both tables.
Join index example in SQL table.
Here, assume you are going to join two different tables, employee and department, based on department_id.
SELECT e.name, d.department_name
FROM employe e
JOIN department d ON e.department_id = d.department_id;
Here, if both the tables, employee.department_id and department.department_id are indexed, then the database can quickly join rows between the two tables using the index, which improves the join performance of both tables.
Fast aggregation and grouping in SQL database table.
Indexing and sorting in SQL database tables can make aggregation and grouping database operations operate fast and smoothly. For example, in database aggregation operations, you can use COUNT(), SUM(), AVG(), MIN(), MAX(), functions and GROUP BY clause in numeric table columns.
- Efficient aggregation – Here, if indexing is applied to the included columns in aggregation or grouping in a SQL database table, then the database can quickly summarize the data using the index method.
- Reduced scan time – Indexing in SQL database tables helps the database to ignore unnecessary table rows and focus only on search related rows for aggregation.
Faster aggregation and grouping example.
Here the employee table is a query that calculates the total salary of employees in each department.
SELECT department_id, SUM(salary)
FROM employe
GROUP BY department_id;
Here in this query an index on department_id will help the database to quickly group the employees by department_id without scanning the total employee table.
Improved performance for range queries in SQL database tables.
Indexing in SQL database tables can be used specifically for range queries, such as BETWEEN, <, >, >=, and <=, which allows for faster retrieving of advanced query results in SQL database tables.
- Range queries – If you frequently try to query data within a specific range of values in a SQL database table, for example, searching for employees with salaries between 30,000 and 50,000, you can immediately search and access the directly related range of rows in an indexed table in the SQL database table without scanning the total rows.
Improved performance for range queries Example.
If you want to retrieve a list of employee rows with salaries between 45,000 and 70,000 in a SQL database table.
SELECT * FROM employe
WHERE salary BETWEEN 45000 AND 70000;
With an index on the salary column in a SQL database table, the database can use indexing to search and retrieve matching rows faster than doing a total table scan.
Advanced uniqueness enforcement in SQL database tables.
Indexing in SQL database tables enforces uniqueness in the table and unique data storage, which helps maintain data integrity. Here a unique indexing defines that no two tables in a SQL database table store the same record values in the row index column.
- Primary keys and unique constraints – When you define a primary key or unique constraint on a column in a SQL database table, an indexing is automatically created on that column. This ensures that no duplicate table record values will be stored in that column.
- Faster checking for uniqueness – When performing INSERT or UPDATE table operations in a SQL database, you can apply indexing to efficiently check whether a value already exists in the existing table.
Advanced uniqueness enforcement example.
If you define a primary key on the employe_id column in a SQL database table, the database will automatically create a unique index to ensure that no two employees have the same employe_id value.
CREATE TABLE employe (
employee_id INT PRIMARY KEY,
name VARCHAR(120),
salary DECIMAL
);
Improved performance for sorting in SQL database tables.
Database table sorting provides advanced improvements in data indexing performance when you need to sort tables in SQL database tables.
ORDER BY Optimization – If a query in a SQL database table contains an ORDER BY clause that matches an indexed column, the database can return the rows in sorted order directly from the index without sorting them separately.
Improved performance for sorting example.
If your existing SQL database table has indexing applied on the employee_id column, and you execute the following table query.
SELECT * FROM employe
ORDER BY employee_id;
Here, the database can retrieve the rows in sorted order directly from the index in the existing SQL database table, making the query perform much faster than performing a sort operation on the aggregate table.
Optimized full-text search in SQL database tables.
For text-based columns in a SQL database table, such as VARCHAR or TEXT, you can create full-text indexing, which enables fast text searches.
- Full-text search – Full-text indexing in SQL database tables helps databases perform fast searches on text data by breaking it into token words and storing them in a structured way that can be accessed quickly.
- Efficient search – Without full-text indexing in SQL database tables, searching on large text fields can be very slow, because the database will need to scan each row for matching text.
SQL database tables example.
Suppose you have a product table with a description column, and you want to search for products with the word “tablet” in their description. A full-text indexing on the description column will make this query fast.
SELECT * FROM product
WHERE MATCH(description) AGAINST (‘tablet’);
Supporting foreign key constraints in SQL database tables.
Indexes in SQL database tables are often automatically created on columns that are in foreign key relationships, which improves performance for database reference integrity tests.
- Faster foreign key checks – When you update or delete a record in a parent table, the database can use indexing on foreign key columns to check whether any child rows exist in the referenced table, making these operations faster and more efficient.
Foreign key constraints example.
When you delete a department from the Departments table, the database checks whether there is an employee associated with the department in the Employees table. If there is an indexing on the department_id column in the Employees table, the database can perform this check more efficiently.
