데이터베이스 샤딩

<div class="demo"><div class="head"><b>user_id % 4</b><span id="user">user 42</span></div><div class="stage shard"><div class="router">ID →</div><div class="shards"><div class="cell">shard 0</div><div class="cell">shard 1</div><div class="cell">shard 2</div><div class="cell">shard 3</div></div></div><div class="foot"><span id="route">42 → shard 2</span><span>one key, one route</span></div></div>

*{box-sizing:border-box}.demo{width:min(96vw,820px);height:min(94vh,350px);padding:clamp(8px,2vmin,18px);border:1px solid var(--line);border-radius:14px;background:var(--surface);color:var(--fg);display:flex;flex-direction:column;gap:clamp(5px,1.5vmin,12px);font:600 clamp(12px,3.5vmin,15px)/1.25 var(--font-sans),sans-serif;overflow:hidden}.head,.foot,.row{display:flex;justify-content:space-between;align-items:center;gap:8px}.head b{color:var(--accent)}.head span,.foot,.muted{color:var(--muted)}.stage{flex:1;min-height:0;display:flex;align-items:center;justify-content:center;gap:8px}.cell,.pill{border:1px solid var(--line);border-radius:8px;background:var(--bg);padding:clamp(4px,1.2vmin,9px);text-align:center}.pill{border-radius:999px}.on{border-color:var(--accent)!important;background:color-mix(in srgb,var(--accent) 17%,var(--surface))!important;color:var(--fg)!important}.bad{border-color:#e16a5d!important;background:color-mix(in srgb,#e16a5d 18%,var(--surface))!important}.foot{font-size:clamp(12px,3vmin,14px)}.shard{justify-content:space-around}.router{font:700 clamp(17px,6vmin,27px) var(--font-sans),sans-serif;text-align:center;color:var(--accent)}.shards{display:grid;grid-template-columns:repeat(2,minmax(65px,1fr));gap:6px;min-width:60%}.shards .cell{white-space:nowrap}

let n=0;const ids=[42,17,28,39];function tick(){document.getElementById('user').textContent='user '+ids[n];document.querySelectorAll('.shards .cell').forEach((e,i)=>e.classList.toggle('on',i===ids[n]%4));document.getElementById('route').textContent=ids[n]+' → shard '+ids[n]%4;n=(n+1)%4}tick();const t=setInterval(tick,850);document.querySelector('.demo').onclick=()=>{clearInterval(t);tick()}