Interview question
How do you optimize slow database queries in PHP applications? PHP applications में slow database queries को कैसे optimize करें?
Answer
| Technique | How it helps |
|---|---|
| Add indexes on frequently queried columns | Avoids full table scans |
| Select only needed columns | Reduces data transfer, avoids SELECT * |
| Use EXPLAIN to analyze queries | Shows whether indexes are actually used |
| Eager load relationships | Avoids N+1 problem |
| Paginate large result sets | Avoids loading thousands of rows at once |
// Analyzing a slow query
EXPLAIN SELECT * FROM orders WHERE customer_id = 5 AND status = 'pending';
// Adding a composite index
CREATE INDEX idx_customer_status ON orders (customer_id, status);
// Selecting only needed columns
$users = User::select('id', 'name', 'email')->get();| Technique | कैसे मदद करता है |
|---|---|
| Frequently queried columns पर indexes | Full table scan से बचाता है |
| ज़रूरी columns ही select करें | Data transfer कम करता है |
| EXPLAIN से query analyze करें | Index इस्तेमाल हो रहा है या नहीं दिखाता है |
EXPLAIN SELECT * FROM orders WHERE customer_id = 5 AND status = 'pending';
CREATE INDEX idx_customer_status ON orders (customer_id, status);Was this answer clear?