SAP 自建数据库表的索引

最新推荐文章于 2024-04-17 17:34:19 发布

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最新推荐文章于 2024-04-17 17:34:19 发布 · 2.8k 阅读

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博客介绍了数据库表索引的作用，指出索引可加快行选择速度。自建表查询慢时可对相应字段做索引，对比显示做索引后查询速度大幅提升。还详细说明了通过SE11事物代码到数据库表创建索引的步骤，最后提到添加索引会占用更多磁盘。

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一背景

An index in a database table helps to speed up the selection of rows. An index is a sorted copy of selected database table fields. An additional field contains a pointer to the actual table rows. Sorting enables faster access to the rows in the table, for example in binary searches. A database table has at least one primary index defined by its key fields. It can also have one or more optional secondary indexes.
The primary index is a unique index constructed from the key fields of the primary key. It is always created automatically in AS ABAP. A maximum of one record exists in the table for each combination of index fields. If the primary index cannot be used to identify the results set, for example because no field from the primary index was selected, the table is scanned in full or an attempt is made to use a suitable secondary index (if one exists).
Alongside the primary index defined using the primary key, both unique and non-un