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# Connection Properties on Apache Arrow Flight SQL ODBC Driver

## Setting ODBC Connection Properties

ODBC connection parameters can be set in a connection string or defined in a DSN. On macOS and Linux, DSNs are typically defined in your system's `odbc.ini`. On Windows they are typically configured with the ODBC Data Source Administrator.

The following sample connection string and sample DSN are two equivalent ways to connect to Arrow.

### Sample Connection String
```
driver={Apache Arrow Flight SQL ODBC Driver};host=127.0.0.1;port=12345;uid=sample_user;pwd=sample_password;useEncryption=false;useWideChar=true;
```

### Sample DSN
```
[Apache Arrow Flight SQL]
driver        = Apache Arrow Flight SQL ODBC Driver
host          = 127.0.0.1
port          = 12345
uid           = sample_user
pwd           = sample_password
useEncryption = false
useWideChar   = true
```

### Driver Connection Options
| Option | Description | Default |
|--------|-------------|---------------|
| `driver` | Required: the driver for this ODBC driver. | `Apache Arrow Flight SQL ODBC Driver` |
| `dsn` | Data Source Name used for configuring the connection. | `Apache Arrow Flight SQL` |
| `host` | The IP address or hostname for the server. | `NONE` |
| `port` | The TCP port number the server uses for ODBC connections. | `NONE` |
| `user` | The username for authentication to the server. | `NONE` |
| `user id` | The username for authentication to the server. | `NONE` |
| `uid` | The username for authentication to the server. | `NONE` |
| `password` | The password for authentication to the server. | `NONE` |
| `pwd` | The password for authentication to the server. | `NONE` |
| `token` | The personal access token for authentication to the server. | `NONE` |
| `useEncryption` | Setting to determine if an SSL-encrypted connection should be used. | `true` |
| `disableCertificateVerification` | Setting to determine if the driver should verify the host certificate against the trust store. | `false` |
| `trustedCerts` | The full path of the .pem file containing certificates for the purpose of verifying the server. | `NONE` |
| `useSystemTrustStore` | Setting to determine whether to use a CA certificate from the system's trust store or from a specified .pem file. | `true` on Windows, `false` on macOS & Linux |
| `stringColumnLength` | Maximum length of a string column. Some apps may require a lower length. | `NONE` |
| `useWideChar` | Setting to determine if wide characters should be used. Important for Unicode applications. | `true` on Windows, `false` on macOS & Linux |
| `chunkBufferCapacity` | Capacity of a chunk buffer. Larger values will improve throughput at the cost of increased memory usage. | 5 |
