相比二叉树，B+树每个节点可以放下占满一个page那么多的数据，从而实现压低树高度的效果。且每次添加，B+树都会自动平衡<sup id="fnref:1"><a href="#fn:1" rel="footnote"><span aria-label="https://blog.allegro.tech/2023/11/how-does-btree-make-your-queries-fast.html">[1]</span></a></sup> 硬盘随机访问速度远低于顺序访问，所以B+树把相近的节点放在一个/相近的page中，能提高命中率. <div id="footnotes"><div id="footnotelist" class="pt3 bt b--gray"><ol style="list-style: none;padding-left: 0;"><li id="fn:1"><span class="dib v-top w-100">1. <a href="https://blog.allegro.tech/2023/11/how-does-btree-make-your-queries-fast.html">https://blog.allegro.tech/2023/11/how-does-btree-make-your-queries-fast.html</a><a href="#fnref:1" rev="footnote"> ↩</a></span></li></ol></div></div>