src/UserGuide/dev-1.3/Tools-System/Schema-Export-Tool.md

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# Metadata Export

## 1. Overview

The metadata export tool `export-schema.sh/bat` is located in the `tools` directory. It can export metadata from a specified database in IoTDB into CSV files.

> Supported since version 1.3.3

## 2. Detailed Functionality

### 2.1 Parameter Description

| Short Parameter | Full Parameter | Description | Required | Default Value |
|-----------------|----------------|-------------|----------|---------------|
| `-h` | `--host` | Hostname | No | 127.0.0.1 |
| `-p` | `--port` | Port number | No | 6667 |
| `-u` | `--username` | Username | No | root |
| `-pw` | `--password` | Password | No | root |
| `-t` | `--target` | Specifies the target directory for output files. The directory will be created if it does not exist | Yes | - |
| `-path` | `--path_pattern` | Specifies the path pattern for metadata export | Yes | - |
| `-pf` | `--path_pattern_file` | Specifies the name of the export file | No | - |
| `-lpf` | `--lines_per_file` | Specifies the maximum number of lines per exported dump file | No | `10000` |
| `-timeout` | `--queryTimeout` | Query timeout for the session (ms) | No | -1. Range: -1 ~ Long.MAX_VALUE = 9223372036854775807 |
| `-help` | `--help` | Displays help information | No | - |

### 2.2 Execution Commands

```Bash
# Unix/OS X
> tools/export-schema.sh [-h <host>] [-p <port>] [-u <username>] [-pw <password>] -t <targetDir>
       [-path <exportPathPattern>] [-pf <exportPathPatternFile>] [-lpf <linesPerFile>]
       [-timeout <timeout>] [-help]

# Windows
> tools\export-schema.bat [-h <host>] [-p <port>] [-u <username>] [-pw <password>] -t <targetDir>
       [-path <exportPathPattern>] [-pf <exportPathPatternFile>] [-lpf <linesPerFile>]
       [-timeout <timeout>] [-help]
```

### 2.3 Usage Example

```Bash
# Export metadata under the root.ln path
./export-schema.sh -t /home/ -path "root.ln.**"
```

```CSV
# Export result format
Timeseries,Alias,DataType,Encoding,Compression
root.ln.wf02.wt02.status,,BOOLEAN,RLE,LZ4
root.ln.wf02.wt02.hardware,,TEXT,PLAIN,LZ4
```