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| author | muqiuhan <[email protected]> | 2025-05-03 10:47:05 +0000 |
|---|---|---|
| committer | muqiuhan <[email protected]> | 2025-05-03 10:47:05 +0000 |
| commit | 3fa50e79f12fe2b66ebd5d643ed597c6a121b198 (patch) | |
| tree | 75dee536b39669352e6c8dd78c01c4e65899fd0e /2025/04/02 | |
| parent | 9d7184b4ef8be81a9c6b7c7c5f21fff94e0ea23a (diff) | |
| download | blog-3fa50e79f12fe2b66ebd5d643ed597c6a121b198.tar.gz | |
deploy: a0dad147ccf1d831c5f48d8d0e868160a23cc92c
Diffstat (limited to '2025/04/02')
| -rw-r--r-- | 2025/04/02/N-1-selects-problem-与-Prisma-ORM/index.html | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/2025/04/02/N-1-selects-problem-与-Prisma-ORM/index.html b/2025/04/02/N-1-selects-problem-与-Prisma-ORM/index.html index 2df41efe..ac98e832 100644 --- a/2025/04/02/N-1-selects-problem-与-Prisma-ORM/index.html +++ b/2025/04/02/N-1-selects-problem-与-Prisma-ORM/index.html @@ -211,7 +211,7 @@ </ol> <p>Prisma ORM 在设计上就考虑了 N+1 问题,并提供了一种既方便开发者又高效的解决方案。当使用 Prisma Client 查询数据并需要包含关联模型时,Prisma 会自动优化查询,<strong>避免产生 N+1 查询</strong>,主要通过<strong>关系查询(Relation Queries)</strong>中的 <code>include</code> 选项或嵌套读取(nested reads)来实现这一点:</p> <p>假设想获取所有用户及其发布的帖子,使用 Prisma Client,可以这样写:</p> -<figure class="highlight typescript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">import</span> { <span class="title class_">PrismaClient</span> } <span class="keyword">from</span> <span class="string">'@prisma/client'</span></span><br><span class="line"></span><br><span class="line"><span class="keyword">const</span> prisma = <span class="keyword">new</span> <span class="title class_">PrismaClient</span>()</span><br><span class="line"></span><br><span class="line"><span class="keyword">async</span> <span class="keyword">function</span> <span class="title function_">getUsersWithPosts</span>(<span class="params"></span>) {</span><br><span class="line"> <span class="keyword">const</span> usersWithPosts = <span class="keyword">await</span> prisma.<span class="property">user</span>.<span class="title function_">findMany</span>({</span><br><span class="line"> <span class="attr">include</span>: {</span><br><span class="line"> <span class="attr">posts</span>: <span class="literal">true</span>, <span class="comment">// 指示 Prisma 加载关联的 posts</span></span><br><span class="line"> },</span><br><span class="line"> })</span><br><span class="line"> <span class="comment">// usersWithPosts 包含了用户列表,每个用户对象中都有一个 posts 数组</span></span><br><span class="line"> <span class="variable language_">console</span>.<span class="title function_">log</span>(usersWithPosts)</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="title function_">getUsersWithPosts</span>()</span><br><span class="line"> .<span class="title function_">catch</span>(<span class="function">(<span class="params">e</span>) =></span> {</span><br><span class="line"> <span class="keyword">throw</span> e</span><br><span class="line"> })</span><br><span class="line"> .<span class="title function_">finally</span>(<span class="keyword">async</span> () => {</span><br><span class="line"> <span class="keyword">await</span> prisma.$disconnect()</span><br><span class="line"> })</span><br></pre></td></tr></table></figure> +<figure class="highlight typescript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">import</span> { <span class="title class_">PrismaClient</span> } <span class="keyword">from</span> <span class="string">'@prisma/client'</span></span><br><span class="line"></span><br><span class="line"><span class="keyword">const</span> prisma = <span class="keyword">new</span> <span class="title class_">PrismaClient</span>()</span><br><span class="line"></span><br><span class="line"><span class="keyword">async</span> <span class="keyword">function</span> <span class="title function_">getUsersWithPosts</span>(<span class="params"></span>) {</span><br><span class="line"> <span class="keyword">const</span> usersWithPosts = <span class="keyword">await</span> prisma.<span class="property">user</span>.<span class="title function_">findMany</span>({</span><br><span class="line"> <span class="attr">include</span>: {</span><br><span class="line"> <span class="attr">posts</span>: <span class="literal">true</span>, <span class="comment">// 指示 Prisma 加载关联的 posts</span></span><br><span class="line"> },</span><br><span class="line"> })</span><br><span class="line"> <span class="comment">// usersWithPosts 包含了用户列表,每个用户对象中都有一个 posts 数组</span></span><br><span class="line"> <span class="variable language_">console</span>.<span class="title function_">log</span>(usersWithPosts)</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="title function_">getUsersWithPosts</span>()</span><br><span class="line"> .<span class="title function_">catch</span>(<span class="function">(<span class="params">e</span>) =></span> {</span><br><span class="line"> <span class="keyword">throw</span> e</span><br><span class="line"> })</span><br><span class="line"> .<span class="title function_">finally</span>(<span class="title function_">async</span> () => {</span><br><span class="line"> <span class="keyword">await</span> prisma.$disconnect()</span><br><span class="line"> })</span><br></pre></td></tr></table></figure> <p>当执行上述查询时,Prisma <strong>不会</strong> 生成 N+1 个 SQL 查询。而是首先会分析请求,并将其转化为数量非常有限的高效 SQL 查询。对于上面这个一对多关系的 <code>include</code> 查询,Prisma 通常会执行以下<strong>两步</strong>(类似于批量加载策略):</p> <ol> @@ -234,6 +234,11 @@ <nav class="post-nav"> <div class="prev-item"> + <div class="icon arrow-left"></div> + <div class="post-link"> + <a href="/2025/04/13/uuidv7-rdbms/">Prev</a> + </div> + </div> <div class="next-item"> |
