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https://issues.apache.org/jira/browse/ARROW-11696?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17297929#comment-17297929
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Dominik Moritz commented on ARROW-11696:
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But {{&[u8]}} does not seem to implement Seek so FileReader does not work.
The error is:
{{the trait bound `&[u8]: Seek` is not satisfied}}
{{ required by `FileReader::<R>::try_new`}}
If I switch to the StreamReader, I get an IO error at runtime:
{{Io error: failed to fill whole buffer}}
So what I implemented was
{{let cursor = std::io::Cursor::new(contents);}}
{{ let reader = match arrow::ipc::reader::FileReader::try_new(cursor) {}}
{{ Ok(reader) => reader,}}
{{ Err(error) => return Err(format!("{}", error).into()),}}
{{ };}}
> [Rust] Create record batches from in memory IPC without memory copies
> ---------------------------------------------------------------------
>
> Key: ARROW-11696
> URL: https://issues.apache.org/jira/browse/ARROW-11696
> Project: Apache Arrow
> Issue Type: Improvement
> Components: Rust
> Reporter: Dominik Moritz
> Priority: Major
>
> I have the IPC format of Arrow record batches in memory (e.g. as {{&[u8]}})
> and would like to create a vector of batches while avoiding as many memory
> copies as possible. It would be great if there was a way to create the vector
> without having to go through the file abstraction.
> I might be misunderstanding the way the file reader works and maybe it does
> not incur memory copies. I think it does, though, since creating arrow record
> batches from a larger arrow buffer takes much longer.
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