Fix the bug when predicate contains columns not specified in prejection, to prevent filtering out data improperly
- Dominant language
- Java
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- 3d 12h
- Merged PRs (30d)
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Description
As is reported in Parquet-427, data will be filtered out improperly under the case where:
1. predicates - requested schema ≠ ∅
2. predicates - file schema = ∅
To give an example:
data:
|a|b|
|-|-|
|1|1|
|2|2|
|3|3|
file schema: a,b, requested schema: a, and predicate: b = 1
we should get:
|a|
|-|
|1|
but we'll end up get nothing, which is wrong.
This issue proposes to fix this.
**Reporter**: [Liwei Lin(Inactive)](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=proflin) / @lw-lin
**Assignee**: [Liwei Lin(Inactive)](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=proflin) / @lw-lin
**Note**: *This issue was originally created as [PARQUET-425](https://issues.apache.org/jira/browse/PARQUET-425). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*
Contributor guide
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Research direction
Start by reading the linked Parquet-427 report and reproducing the issue's example with file schema a,b, requested schema a, and predicate b = 1. No source file or test is named; done means the result retains the row with a = 1 instead of filtering out all data.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- java
- Domain
- databases
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100