Ted-Jiang commented on code in PR #1998:
URL: https://github.com/apache/arrow-rs/pull/1998#discussion_r912606829
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parquet/src/column/page.rs:
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@@ -187,12 +187,29 @@ impl PageWriteSpec {
}
}
+/// Contains metadata for a page
+pub struct PageMetadata {
+ /// The number of rows in this page
+ pub num_rows: usize,
+
+ /// Returns true if the page is a dictionary page
+ pub is_dict: bool,
+}
+
/// API for reading pages from a column chunk.
/// This offers a iterator like API to get the next page.
pub trait PageReader: Iterator<Item = Result<Page>> + Send {
/// Gets the next page in the column chunk associated with this reader.
/// Returns `None` if there are no pages left.
fn get_next_page(&mut self) -> Result<Option<Page>>;
+
+ /// Gets metadata about the next page, returns an error if no
+ /// column index information
+ fn peek_next_page(&self) -> Result<Option<PageMetadata>>;
Review Comment:
👍 really need this abstraction！
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