# FAQ & Caveats

## What problem does deglib solve?

The Dynamic Exploration Graph library (deglib) solves the approximate nearest neighbor (ANN) search problem.
This involves finding data points that are most similar or “closest” to a given query point in a high-dimensional space, without having to check every single data point.

## Memory Management

A graph object owns the feature vectors. If the graph is freed, feature vectors are not longer valid.

```python
feature_vector = graph.get_feature_vector(42)
del graph
print(feature_vector)
```

This will crash as feature_vector is holding a reference to memory that is owned by graph. This can lead to undefined behaviour (most likely segmentation fault).
Be careful to keep objects in memory that are referenced. If you need it use the copy=True option:

```python
feature_vector = graph.get_feature_vector(10, copy=True)
del graph
print(feature_vector)  # no problem
```

Copying feature vectors will be slower.

## Limitations

- The python wrapper at the moment only supports float32 and uint8 feature vectors. For uint8 vectors only L2 Distance is supported.
- Threaded building is not supported for lid=LID.Unknown. Use LID.High or LID.Low instead.