Luosuu commented on issue #40981:
URL: https://github.com/apache/arrow/issues/40981#issuecomment-2037957679
@mapleFU Thank you for reply!
I checked `arrow-rs` and it seems that it can read one page by `get_bytes`
method of `ChunkReader` trait:
```rust
impl ChunkReader for File {
type T = BufReader<File>;
fn get_read(&self, start: u64) -> Result<Self::T> {
let mut reader = self.try_clone()?;
reader.seek(SeekFrom::Start(start))?;
Ok(BufReader::new(self.try_clone()?))
}
fn get_bytes(&self, start: u64, length: usize) -> Result<Bytes> {
let mut buffer = Vec::with_capacity(length);
let mut reader = self.try_clone()?;
reader.seek(SeekFrom::Start(start))?;
let read = reader.take(length as _).read_to_end(&mut buffer)?;
if read != length {
return Err(eof_err!(
"Expected to read {} bytes, read only {}",
length,
read
));
}
Ok(buffer.into())
}
}
```
in my understanding, if we have the position of a page (and also the length
too), can we directly decode that page?
Just like this `get_bytes` method which takes a start and length then it
seek from the start with length.
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