TDengine is a high-performance, scalable time series database with SQL support. This document is TDengine user manual. It mainly introduces the basic concepts, installation, features, SQL, APIs, operation, maintenance, kernel design, etc. It’s written mainly for architects, developers and system administrators.
TDengine is a [high-performance](https://tdengine.com/fast), [scalable](https://tdengine.com/scalable) time series database with [SQL support](https://tdengine.com/sql-support). This document is TDengine user manual. It mainly introduces the basic concepts, installation, features, SQL, APIs, operation, maintenance, kernel design, etc. It’s written mainly for architects, developers and system administrators.
TDengine makes full use of the characteristics of time series data, proposes the concepts of "one table for one data collection point" and "super table", and designs an innovative storage engine, which greatly improves the efficiency of data ingestion, querying and storage. To understand the new concepts and use TDengine in the right way, please read [“concepts”](./concept) thoroughly.
It's very easy to install TDengine and would take you only a few minutes from downloading to finishing installation.
为方便使用，从 2.4.0.10 开始，标准的服务端安装包包含了 taos、taosd、taosAdapter、taosdump、taosBenchmark、TDinsight 安装脚本和示例代码；如果您只需要用到服务端程序和客户端连接的 C/C++ 语言支持，也可以仅下载 lite 版本的安装包。
For the convenience of users, from version 2.4.0.10, the standard server side installation package includes `taos`, `taosd`, `taosAdapter`, `taosBenchmark` and sample code. If only the `taosd` server and C/C++ connector are required, you can also choose to download the lite package.
在安装包格式上，我们提供 tar.gz, rpm 和 deb 格式，为企业客户提供 tar.gz 格式安装包，以方便在特定操作系统上使用。需要注意的是，rpm 和 deb 包不含 taosdump、taosBenchmark 和 TDinsight 安装脚本，这些工具需要通过安装 taosTool 包获得。
Three kinds of packages are provided, tar.gz, rpm and deb. Especially the tar.gz package is provided for the convenience of enterprise customers on different kinds of operating systems, it includes `taosdump` and TDinsight installation script which are normally only provided in taos-tools rpm and deb packages.
Between two major release versions, some beta versions may be delivered for users to try some new features.
<PkgList type={0}/>
具体的安装方法，请参见[安装包的安装和卸载](/operation/pkg-install)。
For the details please refer to [Install and Uninstall](/operation/pkg-install)。
To see the details of versions, please refer to [Download List](https://www.taosdata.com/all-downloads) and [Release Notes](https://github.com/taosdata/TDengine/releases).
@@ -128,7 +128,7 @@ CREATE AGGREGATE FUNCTION ids(X) AS ids(Y) OUTPUTTYPE typename(Z) [ BUFSIZE B ];
- ids(X)：the function name to be sued in SQL statement, must be consistent with the function name defined by `udfNormalFunc`
- ids(Y)：the absolute path of the DLL file including the implementation of the UDF, the path needs to be quoted by single or double quotes
- typename(Z)：the output data type, the value is the literal string of the type 此
- typename(Z)：the output data type, the value is the literal string of the type
- B：the size of intermediate buffer, in bytes; it's an optional parameter and the range is [0,512]
For details about how to use intermediate result, please refer to example program [demo.c](https://github.com/taosdata/TDengine/blob/develop/tests/script/sh/demo.c).
**Description**: The linear regression function of the specified column and the timestamp column (primary key), `start_val` is the initial value and `step_val` is the step value.
**Return value type**:A string in the format of "(slope, intercept)"
**Return value type**:A string in the format of "(slope, intercept)"
**Applicable column types**:Data types except for timestamp, binary, nchar and bool
**Applicable column types**:Data types except for timestamp, binary, nchar and bool
**Applicable column types**: Any data types except for timestamp
**支持版本**: From version 2.6.0.0
**Applicable versions**: From version 2.6.0.0
**More explanations**:
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@@ -809,7 +809,7 @@ Query OK, 2 row(s) in set (0.001162s)
SELECT DERIVATIVE(field_name, time_interval, ignore_negative) FROM tb_name [WHERE clause];
```
**Description**: The derivative of a specific column. The time rage can be specified by parameter `time_interval` 参数指定, the minimum allowed time range is 1 second (1s); the value of `ignore_negative` can be 0 or 1, 1 means negative values are ignored.
**Description**: The derivative of a specific column. The time rage can be specified by parameter `time_interval`, the minimum allowed time range is 1 second (1s); the value of `ignore_negative` can be 0 or 1, 1 means negative values are ignored.
**Return value type**: Double precision floating point
For example, assuming the default value of `maxVgroupPerDB` is 64, the default value of `cache` 16M, the default value of `blocks` is 6, there are 100,000 tables in a DB, the replica number is 1, total length of tag values is 256 bytes, the total memory required for this DB is: 并且一个 DB 中有 10 万张表，单副本，标签总长度是 256 字节，则这个 DB 总的内存需求为：64 \* 1 \* (16 \* 6 + 10) + 100000 \* (0.25 + 0.5) / 1000 = 6792M.
For example, assuming the default value of `maxVgroupPerDB` is 64, the default value of `cache` 16M, the default value of `blocks` is 6, there are 100,000 tables in a DB, the replica number is 1, total length of tag values is 256 bytes, the total memory required for this DB is: 64 \* 1 \* (16 \* 6 + 10) + 100000 \* (0.25 + 0.5) / 1000 = 6792M.
In real operation of TDengine, we are more concerned about the memory used by each TDengine server process `taosd`.在
In real operation of TDengine, we are more concerned about the memory used by each TDengine server process `taosd`.
@@ -10,7 +10,7 @@ TDengine CLI `taos` supports `source <filename>` command for executing the SQL s
## Import from Data File
In TDengine CLI, data can be imported from a CSV file into an existing table. The data in single CSV must belong to same table and must be consistent with the schema of that table. The SQL statement is as below:也
In TDengine CLI, data can be imported from a CSV file into an existing table. The data in single CSV must belong to same table and must be consistent with the schema of that table. The SQL statement is as below:
@@ -108,7 +108,7 @@ From version 2.2.0.0, the above command can be executed on Linux Shell to test t
The parameter `debugFlag` is used to control the log level of `taosd` server process. The default value is 131, for debug purpose it needs to be escalated to 135 or 143.
Once this parameter is set to 135 or 143, the log file grows very quickly especially when there is huge volume of data insertion and data query requests. If all the logs are stored together, some important information may be missed very easily, so on server side important information is stored at different place from other logs.一
Once this parameter is set to 135 or 143, the log file grows very quickly especially when there is huge volume of data insertion and data query requests. If all the logs are stored together, some important information may be missed very easily, so on server side important information is stored at different place from other logs.
- The log at level of INFO, WARNING and ERROR is stored in `taosinfo` so that it is easy to find important information
- The log at level of DEBUG (135) and TRACE (143) and other information not handled by `taosinfo` are stored in `taosdlog`
| Meaning | The switch for monitoring inside server. The workload of the hosts, including CPU, memory, disk, network, TTP requests, are collected and stored in a system builtin database `LOG` |
| Value Range | 0: monitoring disabled, 1: monitoring enabled 务. |
| Value Range | 0: monitoring disabled, 1: monitoring enabled |
| Default Value | 0 |
### monitorInterval
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@@ -159,13 +159,13 @@ TDengine uses continuous 13 ports, both TCP and TCP, from the port specified by
| Meaning | The total memory size reserved for all queries |
| Unit | MB |
| Default Value | None |
| Note | It can be estimated by "maximum number of concurrent queries" _ "number of tables" _ 170 |
### ratioOfQueryCores
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@@ -250,11 +250,11 @@ The locale definition standard on Linux is: <Language\>\_<Region\>.<charset\>, f
### charset
| Attribute | Description |
| ------------- | ---------------------------- |
| Applicable | Server and Client |
| Meaning | Character |
| Default Value | charset set in the system 系 |
| Attribute | Description |
| ------------- | ------------------------- |
| Applicable | Server and Client |
| Meaning | Character |
| Default Value | charset set in the system |
:::info
On Linux, if `charset` is not set in `taos.cfg`, when `taos` is started, the charset is obtained from system locale. If obtaining charset from system locale fails, `taos` would fail to start. So on Linux system, if system locale is set properly, it's not necessary to set `charset` in `taos.cfg`. For example:
