参考文档：https://help.aliyun.com/zh/analyticdb/analyticdb-for-postgresql/user-guide/fusion-search-use-guide?spm=a2c4g.11186623.help-menu-92664.d_2_8_3.4bf95fa2s3zEtw&scm=20140722.H_2528590._.OR_help-....

问答 2024-01-01 来自：开发者社区

OceanBase数据库如何写sql能够指定索引并且不让发生回表，使查询时间缩短呢？

在OceanBase数据库中，如何编写SQL以指定索引并避免发生回表，从而缩短查询时间呢？表中的字段已经创建了索引。通过指定索引查询，执行计划显示发生了回表，预估时间为64秒。而通过指定主键查询，执行计划没有发生回表，预估时间为12秒。

问答 2023-01-30 来自：开发者社区

表格存储SQL 使用二级索引时需要显式查询二级索引映射表，然后自己回表吗？

文章 2023-01-12 来自：开发者社区

1. 什么是索引索引是一个单独存储在磁盘上的数据库结构，它们包含着对数据表里所有记录的引用指针在数据库中，索引用来加速对表的查询，索引技术通过使用快速路径访问的方法快速定位数据，减少了磁盘的I/O可以把索引比作书的目录，每一张表都要有索引，就像每一本书都应该有目录一样。有了索引，数据库的检索速度可以大大提高2. 索引的特点索引是作用于表查询的一项技术，因此创建索引时，需要确保该索引是应用在SQL....

问答 2022-04-15 来自：开发者社区

这条SQL为什么没有引用索引查询？

SELECT title,remark,exp,total,time FROM ms_exp` WHERE ( uid = 1 ) ORDER BY time DESC LIMIT 30,10`上图是SQL分析结果，发现key是NULL，是因为纪录总数只有59条，MySQL觉得没必要用索引，直接给了我结果？

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