apache / apache/datafusion

Add Backtraces to DataFusionError

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#5,283 2 comments 1 reaction 0 assignees View on GitHub
enhancement
Dominant language
Rust
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Description

**Is your feature request related to a problem or challenge? Please describe what you are trying to do.**

It is fairly common to get errors from DataFusion such as in https://github.com/apache/arrow-ballista/issues/665

```
2023-02-12T22:26:10.297254Z ERROR tokio-runtime-worker ThreadId(02) ballista_scheduler::scheduler_server::query_stage_scheduler: Error planning job t9P5iXR: DataFusionError(SchemaError(FieldNotFound { field: Column { relation: Some("part"), name: "p_brand" }, valid_fields: [Column { relation: None, name: "COUNT(DISTINCT partsupp.ps_suppkey)" }] }))
```

Which do not make it easy to understand the context in which the error was encountered. Typically the approach I follow is to use an interactive debugger, such as GDB, to catch the error. However, this requires having a local reproducer, which isn't always possible.

**Describe the solution you'd like**

Backtraces are a commonly used mechanism to automatically provide context on where an error was encountered. Whilst they have issues, especially in async contexts, they are better than the current situation where diagnosing such issues is non-trivial.

Adding a backtrace to the error variants that have corresponding `From` conversions, i.e. `ArrowError`, `ParquetError`, `AvroError`, `ObjectStore`, `IoError`, `SchemaError`, etc... would automatically capture the context in which this conversion is performed.

APIs can then use `DataFusionError::find_root` to get the leaf variant, and from that extract the backtrace if any.

This is predicated on the fact that `DataFusionError` is rarely used to implement control flow, and so the cost of obtaining a backtrace is only paid on exceptional paths.

**Describe alternatives you've considered**

**Additional context**
Add any other context or screenshots about the feature request here.

Contributor guide

Open the contributing guide

Research direction

Start by reading DataFusionError::find_root and the From conversions for ArrowError, ParquetError, AvroError, ObjectStore, IoError, and SchemaError. Trace how these variants are represented and how callers can access the leaf error. Done means the relevant conversions capture backtraces and callers can extract them from the leaf variant.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
backend
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
42/100

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