Django Model Fields Indexing : <p>I only know that indexing is helpful and it queries faster.</p>

<p>What is the difference between following two?</p>

<pre><code>1. class Meta:
       indexes = [
           models.Index(fields=['last_name', 'first_name',]),
           models.Index(fields=['-date_of_birth',]),
]

2. class Meta:
       indexes = [
            models.Index(fields=['first_name',]),
            models.Index(fields=['last_name',]),
            models.Index(fields=['-date_of_birth',]),
]
</code></pre>
