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# FAQ

## What is a magic?

One may be unfamiliar with the commands prefixed with `%` used in this instruction. Here is a detailed description of this command and its usage. 

### Definition of Jupyter Magic

Magics are specific to and provided by the IPython kernel. Some common usage of magic functions are: running external code files, timing code execution, and loading IPython Extensions. 

Suppose execute.py is a python code file

```
%run execute.py
%timeit L = [n ** 2 for n in range(1000)] (Timing executions -- will return 1000 loops, best of 3: 325 µs per loop)
```

In our code above, we use **%load_ext** to load an IPython extension by its module name, `sql`, and then directly use the extension by using `%sql`.

```
load an IPython extension by its module name.
%load_ext sql 
```

### Line Magic VS Cell Magic

**Line magics**, which are denoted by a single % prefix and operate on a single line of input, and **cell magics**, which are denoted by a double %% prefix and operate on multiple lines of input. 

For example, for the code above, **%sql** is a line magic, and **%%sql** is a code magic. 

### Reference 

[IPython doc](https://ipython.readthedocs.io/en/stable/interactive/magics.html#cell-magics)

[Python Data Science Handbook](https://jakevdp.github.io/PythonDataScienceHandbook/01.03-magic-commands.html)

+++ {"user_expressions": []}

## Connecting to `impala`

For an `impala` connection with [`impyla`](https://github.com/cloudera/impyla) for HiveServer2, you need to disable autocommit:

```
%config SqlMagic.autocommit=False
%sql impala://hserverhost:port/default?kerberos_service_name=hive&auth_mechanism=GSSAPI
```