Why Reporting Becomes Painfully Slow as Data Grows (And How I Solved It)

The Problem

Reports worked perfectly in the beginning.

But as days passed and data increased:

• Daily reports became slower
• Monthly summaries timed out
• SUM queries took several seconds
• Database CPU usage spiked

This is a classic scaling problem.

Why Reporting Gets Slower Over Time

Most reporting queries rely heavily on:

SELECT SUM(amount)
FROM transactions
WHERE created_at BETWEEN ? AND ?;
As the table grows:

Millions of rows are scanned

Indexes help, but only to a point

Aggregations become expensive

This is especially painful in:

Financial systems

Betting platforms

Analytics dashboards

The Hidden Cost of SUM()
Indexes do not store sums — they only help locate rows.

So even with indexes:

The database still needs to scan many rows

Aggregation happens row by row

Result:
❌ Slow dashboards
❌ Timeouts
❌ Heavy load on primary DB

The Solution: Summary Tables
Instead of calculating totals from raw data every time, I introduced pre-aggregated summary tables.

Example: Daily Summary Table
daily_transaction_summary
- date
- total_amount
- total_count
Data Flow
Raw transactions stored normally

Background job updates summary table

Reports read from summary table

Laravel Implementation
DailyTransactionSummary::updateOrCreate(
    ['date' => today()],
    [
        'total_amount' => DB::raw('total_amount + ' . $amount),
        'total_count' => DB::raw('total_count + 1'),
    ]
);
Indexing Matters (A Lot)
Proper indexing made a huge difference:

Index on date

Composite indexes for report filters

Avoid unnecessary columns in SELECT

Example:

CREATE INDEX idx_summary_date ON daily_transaction_summary(date);
Performance Gains
Before:

Report load time: 8–12 seconds

Heavy DB load

After:

Report load time: < 200ms

Stable performance even with years of data

Key Lessons
Reporting queries don’t scale linearly

SUM on large tables is expensive

Summary tables are not premature optimization — they are necessary

Separate transactional data from reporting data

Final Thoughts
Scaling is not about writing smarter queries —
it’s about changing how data is consumed.

If your system is growing daily, your reporting strategy must grow with it.