alamb commented on code in PR #7479:
URL: https://github.com/apache/arrow-rs/pull/7479#discussion_r2078221299
##########
parquet/src/arrow/arrow_reader/mod.rs:
##########
@@ -314,17 +317,26 @@ impl ArrowReaderOptions {
}
}
- /// Provide a schema to use when reading the parquet file. If provided it
- /// takes precedence over the schema inferred from the file or the schema
defined
- /// in the file's metadata. If the schema is not compatible with the file's
- /// schema an error will be returned when constructing the builder.
+ /// Provide a schema to use when reading the Parquet file.
+ ///
+ /// If provided, this schema takes precedence over any schema defined in
the
+ /// file's schema hint in the metadata (see the [`arrow`] documentation
for more details).
+ /// If the provided schema is not compatible with the data stored in the
+ /// parquet file schema, an error will be returned when constructing the
+ /// builder.
+ ///
+ /// This option is only required if you want to explicitly control the
+ /// conversion of Parquet types to Arrow types, such as casting a column to
+ /// a different type. For example, if you wanted to read an Int64 in
+ /// a Parquet file to a [`TimestampMicrosecondArray`] in the Arrow schema.
Review Comment:
It does error, see
- https://github.com/apache/arrow-rs/pull/7481#
##########
parquet/src/arrow/arrow_reader/mod.rs:
##########
@@ -314,17 +317,26 @@ impl ArrowReaderOptions {
}
}
- /// Provide a schema to use when reading the parquet file. If provided it
- /// takes precedence over the schema inferred from the file or the schema
defined
- /// in the file's metadata. If the schema is not compatible with the file's
- /// schema an error will be returned when constructing the builder.
+ /// Provide a schema to use when reading the Parquet file.
+ ///
+ /// If provided, this schema takes precedence over any schema defined in
the
+ /// file's schema hint in the metadata (see the [`arrow`] documentation
for more details).
+ /// If the provided schema is not compatible with the data stored in the
+ /// parquet file schema, an error will be returned when constructing the
+ /// builder.
+ ///
+ /// This option is only required if you want to explicitly control the
+ /// conversion of Parquet types to Arrow types, such as casting a column to
+ /// a different type. For example, if you wanted to read an Int64 in
+ /// a Parquet file to a [`TimestampMicrosecondArray`] in the Arrow schema.
Review Comment:
It does error, see tests in
- https://github.com/apache/arrow-rs/pull/7481#
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