apache / apache/arrow-java

[java] cannot read datasets with many columns

Open
#199 1 comment 0 reactions 0 assignees View on GitHub
Type: bug
Dominant language
Java
Stars
94
Forks
152
Avg merge
3d 16h
Merged PRs (30d)
11

Description

### Describe the bug, including details regarding any error messages, version, and platform.

Dataset API gets stuck if one tries to read many columns (100k+) from a parquet or arrow file. The API works if the amount of columns is narrowed via projection.

**Reproduction:**

Use the code from the [example](https://arrow.apache.org/cookbook/java/dataset.html#constructing-datasets) and try to read a file with 100k columns. No batch will be loaded even if the batch size is 1.

version: arrow-dataset 11.0

### Component(s)

Java

Contributor guide

Open the contributing guide

Research direction

Start with the Java Dataset API and the linked dataset construction example, reproducing the hang with a parquet or Arrow file containing 100k+ columns and a batch size of 1. Trace the read path while comparing it with a narrowed projection; done means batches load without getting stuck for the reported wide dataset case.

Written by the indexing model from the issue text.

Assessment

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

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