Database Indexing: Speed Up Queries the Right Way

Indexes make database lookups faster by allowing the database to find rows without scanning the entire table.

    Indexes are helpful when you frequently filter or join by a column.
    
    ## Example: searching posts by user_id
    
    If you often run:
    - WHERE user_id = ?
    Then indexing user_id improves performance.
    
    ## Add an index in a migration
    
    ```php
    Schema::table('posts', function (Blueprint $table) {
      $table->index('user_id');
    });
    ```
    
    ## Composite index example
    
    If you filter by both:
    - user_id
    - status
    
    ```php
    $table->index(['user_id', 'status']);
    ```
    
    ## Graph: Full scan vs index
    
    ```mermaid
    flowchart LR
      A[Query WHERE user_id=5] --> B{Index exists?}
      B -->|No| C[Scan all rows]
      B -->|Yes| D[Jump to matching rows]
    ```
    
    In the next tutorial, we will profile queries and catch slow endpoints.