Bug Report: Column Nullability Not Honored in FlightSqlProducer Schema

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Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
55/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Stale
Tech stack
java
Domain
databases

Research direction

Start with org.apache.arrow.driver.jdbc.utils.ConvertUtils.convertArrowFieldsToColumnMetaDataList(), which converts Arrow Field objects into ColumnMetaData instances for the Flight SQL driver. Check how the ColumnMetaData.Builder is populated and verify that the resulting metadata preserves each field's nullability. Done means nullable and non-nullable Arrow fields expose matching ResultSetMetaData values.

Written by the indexing model from the issue text.

Description

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

In the FlightSqlProducer class, the getFlightInfoPreparedStatement method is responsible for returning the Arrow Schema of the ResultSet for a given query. However, the returned schema does not accurately reflect the nullability of columns. Regardless of whether a column is defined as nullable or non-nullable, the schema always returns a fixed nullability value.

This leads to incorrect ResultSetMetaData when the schema is consumed via the Flight SQL driver.

Root Cause:

The issue originates in the method:

org.apache.arrow.driver.jdbc.utils.ConvertUtils.convertArrowFieldsToColumnMetaDataList()

Here, a list of org.apache.arrow.vector.types.pojo.Field objects is converted into org.apache.calcite.avatica.ColumnMetaData instances. However, the setNullable property of the ColumnMetaData.Builder is not being set based on the actual nullability of the Arrow field.

Expected Behavior:

The setNullable method of ColumnMetaData.Builder should be updated to reflect the value of field.isNullable() from the Arrow schema.

Impact:

This bug results in incorrect metadata being exposed to clients using the Flight SQL driver, potentially leading to misinterpretation of the data schema.

Dominant language
Java
Stars
95
Forks
154
Avg merge
2d 10h
Merged PRs (30d)
11

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