thinkharderdev opened a new pull request #1709:
URL: https://github.com/apache/arrow-datafusion/pull/1709
# Which issue does this PR close?
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Closes #1669
# Rationale for this change
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the issue then this section is not needed.
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Previously, we added the ability to merge parquet files on read when they
contain mergeable schemas. This PR abstracts that functionality into a generic
`SchemaAdapter` struct which can perform the basic operations of mapping
projected column indexes from the merged schema to the file schema and also
conforming the file record batch to the merged schema.
This was already supported in Avro/CSV/NdJson since they are already mapping
projections by column name rather than index and adding null-values columns in
the case of missing columns in the file. Added test cases to the relevant
formats to verify this is the case.
# What changes are included in this PR?
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1. Add `SchemaAdapter` struct and use it in `ParquetExec`.
2. Add test cases for Avro/CSV/Json formats to verify existing behavior.
# Are there any user-facing changes?
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No
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No
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