9 ways to tune SQL performance

Here are explanations and examples for the 9 techniques to improve the performance of SQL:

1. Indexing:

Create an index on columns that are frequently used in search and join conditions to speed up query execution. For example, suppose you have a table named "orders" and you frequently search for orders by customer ID:

CREATE INDEX idx_orders_customer_id ON orders (customer_id);

2.Normalization:

Normalize the database tables to minimize data redundancy and improve data integrity. For example, consider a table named "orders" that contains both customer and order information. Normalize this table into two separate tables, "customers" and "orders", to reduce data redundancy.
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3. Query optimization:

Use the EXPLAIN statement to analyze query execution plans and optimize SQL queries for performance. For example:

EXPLAIN SELECT * FROM orders WHERE customer_id = 123;

4. Use proper data types:

Use appropriate data types for columns to reduce memory usage and improve query performance. For example, use an integer data type for the "customer_id" column instead of a string data type.

5. Partitioning:

Partition large tables into smaller, more manageable pieces to speed up queries and improve manageability. For example, partition the "orders" table by order date

CREATE TABLE orders_2022 PARTITION OF orders FOR VALUES FROM ('2022-01-01') TO ('2022-12-31');

6. Avoid N+1 queries:

Use JOINs or subqueries instead of multiple single row queries to reduce the number of database round trips. For example, use a join to retrieve all orders and customer information in a single query:

SELECT o.*, c.*
FROM orders o
JOIN customers c ON o.customer_id = c.id;

7. Caching:

Implement caching at the application level or use database caching mechanisms like query result caching to reduce the load on the database.

8. Avoid wildcard searches:

Use specific searches with indexes instead of wildcard searches, which can be slow and resource-intensive. For example, search for a specific customer name instead of using a wildcard search:

SELECT * FROM customers WHERE name = 'John Doe';

9. Use prepared statements:

Use prepared statements instead of dynamically constructing and executing SQL statements to reduce parse time and improve performance. For example:

PREPARE stmt1 FROM "SELECT * FROM orders WHERE customer_id = ?";
EXECUTE stmt1 USING 123;
DEALLOCATE PREPARE stmt1;