Optimize Budget model performance by preventing N+1 queries #2504

2025-07-23T19:12:14+08:00

SyedaAnshrahGillani commented

2025-07-23 19:12:14 +08:00

(Migrated from github.com)

Problem

The Budget model was suffering from N+1 query issues, leading to excessive database calls and performance degradation when rendering budget donut charts.

Before Optimization

to_donut_segments_json method was causing N+1 queries due to:
- Loading each budget_category and its category separately
- Repeated lookup calls for category expenses

Solution

Pre-computed category totals using an index_by for O(1) lookup.
Applied includes(:category) explicitly to ensure categories are preloaded, reducing query count.
Same optimization was applied to allocated_spending method.

After Optimization

Fixed to avoid repeated and expensive lookups per budget_category
Now only 2 queries total: preload + expense totals

Impact

This optimization is expected to significantly improve performance for users with many budget categories by reducing:

Response time for rendering budget sections
Database load on budget-related pages

Testing

Added comprehensive test coverage to validate no regression in behavior and verified query count reduction.

## Problem The Budget model was suffering from N+1 query issues, leading to excessive database calls and performance degradation when rendering budget donut charts. ### Before Optimization - **to_donut_segments_json** method was causing N+1 queries due to: - Loading each `budget_category` and its `category` separately - Repeated lookup calls for category expenses ## Solution - Pre-computed category totals using an `index_by` for O(1) lookup. - Applied `includes(:category)` explicitly to ensure categories are preloaded, reducing query count. - Same optimization was applied to `allocated_spending` method. ### After Optimization - Fixed to avoid repeated and expensive lookups per `budget_category` - Now only 2 queries total: preload + expense totals ## Impact This optimization is expected to significantly improve performance for users with many budget categories by reducing: - Response time for rendering budget sections - Database load on budget-related pages ## Testing Added comprehensive test coverage to validate no regression in behavior and verified query count reduction.

Pull request closed

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Reference: gavin/maybe#2504