From 7ebbce45428828fbedf228ad873c09534223641f Mon Sep 17 00:00:00 2001 From: Xiaoyu Wang Date: Wed, 28 Sep 2022 15:12:28 +0800 Subject: [PATCH] docs: improve the system table chapter --- docs/en/12-taos-sql/22-meta.md | 16 ++++++++++++++-- docs/zh/12-taos-sql/22-meta.md | 16 ++++++++++++++-- 2 files changed, 28 insertions(+), 4 deletions(-) diff --git a/docs/en/12-taos-sql/22-meta.md b/docs/en/12-taos-sql/22-meta.md index 9bda5a0a10..8635fbc3dc 100644 --- a/docs/en/12-taos-sql/22-meta.md +++ b/docs/en/12-taos-sql/22-meta.md @@ -11,7 +11,15 @@ TDengine includes a built-in database named `INFORMATION_SCHEMA` to provide acce 4. Future versions of TDengine can add new columns to INFORMATION_SCHEMA tables without affecting existing business systems. 5. It is easier for users coming from other database management systems. For example, Oracle users can query data dictionary tables. -Note: SHOW statements are still supported for the convenience of existing users. +:::info + +- SHOW statements are still supported for the convenience of existing users. +- Some columns in the system table may be keywords, and you need to use the escape character '\`' when querying, for example, the query database test has several VGROUPs: +```sql + select `vgroups` from ins_databases where name = 'test'; +``` + +::: This document introduces the tables of INFORMATION_SCHEMA and their structure. @@ -102,7 +110,11 @@ Provides information about user-created databases. Similar to SHOW DATABASES. | 24 | wal_retention_period | INT | WAL retention period | | 25 | wal_retention_size | INT | Maximum WAL size | | 26 | wal_roll_period | INT | WAL rotation period | -| 27 | wal_segment_size | WAL file size | +| 27 | wal_segment_size | BIGINT | WAL file size | +| 28 | stt_trigger | SMALLINT | The number of files placed on the disk that trigger file merging | +| 29 | table_prefix | SMALLINT | The table name is used for the prefix length that needs to be ignored when calculating the consistent HASH | +| 30 | table_suffix | SMALLINT | The table name is used for the suffix length that needs to be ignored when calculating the consistent HASH | +| 31 | tsdb_pagesize | INT | Page size for vnode data storage engine, in KB | ## INS_FUNCTIONS diff --git a/docs/zh/12-taos-sql/22-meta.md b/docs/zh/12-taos-sql/22-meta.md index c1ffc4a757..c3d8e6868d 100644 --- a/docs/zh/12-taos-sql/22-meta.md +++ b/docs/zh/12-taos-sql/22-meta.md @@ -12,7 +12,15 @@ TDengine 内置了一个名为 `INFORMATION_SCHEMA` 的数据库，提供对数 4. TDengine 在后续演进中可以灵活的添加已有 INFORMATION_SCHEMA 中表的列，而不用担心对既有业务系统造成影响 5. 与其他数据库系统更具互操作性。例如，Oracle 数据库用户熟悉查询 Oracle 数据字典中的表 -Note: 由于 SHOW 语句已经被开发者熟悉和广泛使用，所以它们仍然被保留。 +:::info + +- 由于 SHOW 语句已经被开发者熟悉和广泛使用，所以它们仍然被保留。 +- 系统表中的一些列可能是关键字，在查询时需要使用转义符'\`'，例如查询数据库 test 有几个 VGROUP： +```sql + select `vgroups` from ins_databases where name = 'test'; +``` + +::: 本章将详细介绍 `INFORMATION_SCHEMA` 这个内置元数据库中的表和表结构。 @@ -103,7 +111,11 @@ Note: 由于 SHOW 语句已经被开发者熟悉和广泛使用，所以它们 | 24 | wal_retention_period | INT | WAL 的保存时长 | | 25 | wal_retention_size | INT | WAL 的保存上限 | | 26 | wal_roll_period | INT | wal 文件切换时长 | -| 27 | wal_segment_size | wal 单个文件大小 | +| 27 | wal_segment_size | BIGINT | wal 单个文件大小 | +| 28 | stt_trigger | SMALLINT | 表示落盘文件触发文件合并的个数 | +| 29 | table_prefix | SMALLINT | 表示表名用于计算一致性 HASH 时需要忽略的前缀长度 | +| 30 | table_suffix | SMALLINT | 表示表名用于计算一致性 HASH 时需要忽略的后缀长度 | +| 31 | tsdb_pagesize | INT | 一个 VNODE 中时序数据存储引擎的页大小 | ## INS_FUNCTIONS