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https://issues.apache.org/jira/browse/ARROW-5377?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16932814#comment-16932814
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Wes McKinney commented on ARROW-5377:
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This is still incomplete -- having {{IpcPayload} has gotten us most of the way
there. I think we only need to implement a function to return the exact
encapsulated message size given an {{IpcPayload}}, so that an appropriate piece
of memory can be allocated.
> [C++] Develop interface for writing a RecordBatch IPC stream into
> pre-allocated space (e.g. memory map) that avoids unnecessary serialization
> ---------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: ARROW-5377
> URL: https://issues.apache.org/jira/browse/ARROW-5377
> Project: Apache Arrow
> Issue Type: Improvement
> Components: C++
> Reporter: Wes McKinney
> Priority: Major
>
> As discussed in recent mailing list thread
> https://lists.apache.org/thread.html/b756209052fecb8c28a5eb37db7aecb82a5f5351fa79a9d86f0dba3e@%3Cuser.arrow.apache.org%3E
> The only viable process at the moment for getting an accurate report of
> stream size is to write a simulated stream using {{MockOutputStream}}. This
> is suboptimal for a couple of reasons:
> * Flatbuffers metadata must be created twice
> * Record batch disassembly into IpcPayload must be performed twice
> It seems like an interface with a very constrained public API could be
> provided to deconstruct a sequence of RecordBatches and report the size of
> the produced IPC stream (based on metadata sizes, and padding), and then this
> deconstructed set of IPC payloads can be written out to a stream (e.g. using
> {{FixedSizeBufferWriter}})
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