> For the complete documentation index, see [llms.txt](https://doc.tanmer.cn/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://doc.tanmer.cn/shu-ju-ku/postgre-xl/data-definition.md).

# Data Definition

## Table Basics

## Default Values

## Constraints

## System Columns

## Modifying Tables