51zero / 51zero/eel-sdk

Can Parquet and Orc sources support path expressions on the schema projection?

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enhancement
主要语言
Scala
星标
147
派生
32
PR 合并指标
30 天内没有已合并 PR

描述

- I can successfully write out rows with structs like so with Parquet:
```scala
val personDetailsStruct = Field.createStructField("PERSON_DETAILS",
Seq(
Field("NAME", StringType),
Field("AGE", IntType.Signed),
Field("SALARY", DecimalType(Precision(38), Scale(5))),
Field("CREATION_TIME", TimestampMillisType)
)
)
val schema = StructType(personDetailsStruct)

val rows = Vector(
Vector(Vector("Fred", 50, BigDecimal("50000.99000"), new Timestamp(System.currentTimeMillis()))),
Vector(Vector("Gary", 50, BigDecimal("20000.34000"), new Timestamp(System.currentTimeMillis()))),
Vector(Vector("Alice", 50, BigDecimal("99999.98000"), new Timestamp(System.currentTimeMillis())))
)
Frame.fromValues(schema, rows)
.to(ParquetSink(parquetFilePath))
```
- But **fails** to read it back using the path expression **PERSON_DETAILS.NAME**:
```scala
ParquetSource(parquetFilePath)
.withProjection("PERSON_DETAILS.NAME")
.toFrame()
.collect()
.foreach(row => println(row))
```
- Note path expressions **work** with **withPredicate**

```scala
ParquetSource(parquetFilePath)
.withPredicate(Predicate.or(Predicate.equals("PERSON_DETAILS.NAME", "Alice"), Predicate.equals("PERSON_DETAILS.NAME", "Gary")))
.toFrame()
.collect()
.foreach(row => println(row))
```
- Note a **Hive** table pointing at this file works using the following **HiveQL** syntax:
```sql
hive> select person_details.name, person_details.age
> from struct_person
> where person_details.name in ('Alice', 'Gary' );
OK
Gary 50
Alice 50
Time taken: 0.067 seconds, Fetched: 2 row(s)
hive>
```

贡献指南

这个仓库没有索引到贡献指南

调研方向

Look at the ParquetSource and OrcSource classes to see how projection is handled. The issue shows that path expressions work for predicates but not for schema projection. Start by examining the projection parsing logic and compare it with predicate parsing. Check if the projection logic correctly handles nested struct fields like PERSON_DETAILS.NAME. Run the provided test code to reproduce the failure.

由索引模型根据 Issue 内容生成。

评估

技术栈
scala
领域
data-engineering
Issue 类型
缺陷
难度
3/5
预计耗时
1-2 天
活跃度
停滞
描述清晰度
描述清楚
新手友好度
45/100

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