https://example.org/tags/database/Recent content in Database on 我思故我在Hugo -- gohugo.iozh-cn© 2026 博主Sat, 15 Aug 2026 10:00:00 +0800https://example.org/db/postgresql-intro/Sat, 15 Aug 2026 10:00:00 +0800https://example.org/db/postgresql-intro/<h2 class="relative group">什么是 PostgreSQL <div id="什么是-postgresql" class="anchor"></div> <span class="absolute top-0 w-6 transition-opacity opacity-0 -start-6 not-prose group-hover:opacity-100 select-none"> <a class="text-primary-300 dark:text-neutral-700 !no-underline" href="#%e4%bb%80%e4%b9%88%e6%98%af-postgresql" aria-label="锚点">#</a> </span> </h2> <p>PostgreSQL 是一款功能强大的开源关系型数据库，以<strong>可靠性</strong>和<strong>扩展性</strong>著称，支持丰富的数据类型、全文检索、JSON 与地理信息处理。</p>https://example.org/db/sql-tuning/Sat, 15 Aug 2026 09:00:00 +0800https://example.org/db/sql-tuning/<h2 class="relative group">定位慢查询 <div id="定位慢查询" class="anchor"></div> <span class="absolute top-0 w-6 transition-opacity opacity-0 -start-6 not-prose group-hover:opacity-100 select-none"> <a class="text-primary-300 dark:text-neutral-700 !no-underline" href="#%e5%ae%9a%e4%bd%8d%e6%85%a2%e6%9f%a5%e8%af%a2" aria-label="锚点">#</a> </span> </h2> <ul> <li>开启慢查询日志：<code>log_min_duration_statement</code></li> <li>用 <code>EXPLAIN ANALYZE</code> 分析执行计划</li> <li>关注 <code>pg_stat_statements</code> 统计高频 SQL</li> </ul> <h2 class="relative group">常见性能杀手 <div id="常见性能杀手" class="anchor"></div> <span class="absolute top-0 w-6 transition-opacity opacity-0 -start-6 not-prose group-hover:opacity-100 select-none"> <a class="text-primary-300 dark:text-neutral-700 !no-underline" href="#%e5%b8%b8%e8%a7%81%e6%80%a7%e8%83%bd%e6%9d%80%e6%89%8b" aria-label="锚点">#</a> </span> </h2> <ul> <li><strong>全表扫描</strong>：缺少索引或查询条件无法命中索引</li> <li><strong>隐式类型转换</strong>：索引列上做函数运算导致索引失效</li> <li><strong>N+1 查询</strong>：循环内逐条查询</li> <li><strong>大偏移分页</strong>：<code>OFFSET 1000000</code> 越翻越慢</li> </ul> <h2 class="relative group">优化手段 <div id="优化手段" class="anchor"></div> <span class="absolute top-0 w-6 transition-opacity opacity-0 -start-6 not-prose group-hover:opacity-100 select-none"> <a class="text-primary-300 dark:text-neutral-700 !no-underline" href="#%e4%bc%98%e5%8c%96%e6%89%8b%e6%ae%b5" aria-label="锚点">#</a> </span> </h2> <ul> <li>改写 SQL：用小结果集驱动大表（<code>FROM</code> 顺序）</li> <li>合理利用索引：覆盖索引、复合索引</li> <li>适当反规范化：预计算汇总表</li> </ul> <h2 class="relative group">小结 <div id="小结" class="anchor"></div> <span class="absolute top-0 w-6 transition-opacity opacity-0 -start-6 not-prose group-hover:opacity-100 select-none"> <a class="text-primary-300 dark:text-neutral-700 !no-underline" href="#%e5%b0%8f%e7%bb%93" aria-label="锚点">#</a> </span> </h2> <p>SQL 调优的核心是<strong>理解执行计划</strong>。先定位瓶颈，再对症下药，避免盲目加索引。</p>https://example.org/db/backup-recovery/Fri, 14 Aug 2026 09:00:00 +0800https://example.org/db/backup-recovery/<h2 class="relative group">为什么备份如此重要 <div id="为什么备份如此重要" class="anchor"></div> <span class="absolute top-0 w-6 transition-opacity opacity-0 -start-6 not-prose group-hover:opacity-100 select-none"> <a class="text-primary-300 dark:text-neutral-700 !no-underline" href="#%e4%b8%ba%e4%bb%80%e4%b9%88%e5%a4%87%e4%bb%bd%e5%a6%82%e6%ad%a4%e9%87%8d%e8%a6%81" aria-label="锚点">#</a> </span> </h2> <p>数据是系统的核心资产。硬件故障、误操作、勒索软件——任何意外都可能造成不可挽回的损失。<strong>没有备份的数据，等于没有数据。</strong></p>https://example.org/db/postgresql-index-tuning/Thu, 13 Aug 2026 09:00:00 +0800https://example.org/db/postgresql-index-tuning/<h2 class="relative group">索引为什么重要 <div id="索引为什么重要" class="anchor"></div> <span class="absolute top-0 w-6 transition-opacity opacity-0 -start-6 not-prose group-hover:opacity-100 select-none"> <a class="text-primary-300 dark:text-neutral-700 !no-underline" href="#%e7%b4%a2%e5%bc%95%e4%b8%ba%e4%bb%80%e4%b9%88%e9%87%8d%e8%a6%81" aria-label="锚点">#</a> </span> </h2> <p>没有索引的表扫描是 O(n) 的，数据量上来后查询会急剧变慢。合理的索引能把查询降到 O(log n)。</p>