Best Practices for Handling Calculations in a Live Data source
The best approach to performing calculations in the live data source is to pre-aggregate fields in the backend (database). This article explains how to implement and manage pre-aggregated fields in live databases. These fields store computed aggregate values, optimizing performance for queries that require frequent aggregation.
Steps to Implement Pre-Aggregated Field
1. Create the Orders Table
First, define a table named orders with columns for storing basic information such as name, age, email, and creation timestamp.
CREATE TABLE MySQL_DataBase.orders (
id INT AUTO_INCREMENT PRIMARY KEY, -- Auto-incrementing primary key
name VARCHAR(50), -- Name column
age INT, -- Age column
email VARCHAR(100), -- Email column
created_at DATETIME -- Timestamp column
);
2. Insert Sample Data
Next, populate the table with sample records for demonstration purposes.
INSERT INTO MySQL_DataBase.orders (name, age, email, created_at) VALUES
('John Doe', 30, 'john.doe@example.com', NOW()),
('Jane Smith', 25, 'jane.smith@example.com', NOW()),
('Alice Brown', 28, 'alice.brown@example.com', NOW()),
('Bob White', 35, 'bob.white@example.com', NOW()),
('Charlie Black', 40, 'charlie.black@example.com', NOW());
3. Add a Pre-Aggregated Column
Add a new column named AggregatedField to store the calculated value.
ALTER TABLE MySQL_DataBase.orders ADD COLUMN AggregatedField INT;
4. Update Pre-Aggregated Field
Calculate and update the AggregatedField column using a derived table to avoid Error Code: 1093.
UPDATE MySQL_DataBase.orders
SET AggregatedField = (
SELECT TotalCount
FROM (
SELECT COUNT(id) AS TotalCount
FROM test2.orders
) AS DerivedTable
);
Benefits of Using Pre-Aggregated Fields
- Performance Optimization: Reduces the need to recalculate aggregate functions on large datasets.
- Simplified Queries: Allows reports and dashboards to directly utilize pre-computed values.
- Scalability: Enhances performance for systems that handle high query loads.
Best Practices
- Indexing: Ensure appropriate indexes on fields used in calculations.
- Triggers or Scripts: Automate the update of pre-aggregated fields when data changes.
- Batch Updates: For large datasets, consider batch updates to minimize performance impact.
Example Query
To retrieve data from the orders table, including the pre-aggregated field, use the following query
SELECT id, name, age, email, created_at, AggregatedField
FROM MySQL_DataBase.orders;
Connect this pre-aggregated database in Bold BI, and create a dashboard by adding charts, grids, or KPIs to display the pre-aggregated metrics.
For example, use the AggregatedField column to display the total count directly in a KPI widget.
By implementing pre-aggregated fields as demonstrated in this article, you can significantly enhance query efficiency and improve the overall performance of database-driven applications.
Additional References
