Client-side chunks 2: introduce TransportChunk
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crates/re_chunk/src/transport.rs
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| /// The marker used to identify whether a column is sorted in field-level [`ArrowSchema`] metadata. | ||
| /// | ||
| /// The associated value is irrelevant -- if this marker is present, then it is true. | ||
| pub const FIELD_METADATA_MARKER_IS_SORTED: &'static str = Self::CHUNK_METADATA_MARKER_IS_SORTED; |
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I don't understand how this would be used in practice. All columns must have the same sort order within a chunk. This value seems like it would always have to match CHUNK_METADATA_MARKER_IS_SORTED
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Ahh, I think I understand, but could probably use an improved name / comment.
It seems like:
- CHUNK_METADATA_MARKER_IS_SORTED => This chunk is sorted by row-id
- FIELD_METADATA_MARKER_IS_SORTED => This chunk is sorted on this timeline
If all timelines are monotically increasing they all might be set, but it's possible to be sorted by row-id, but not sorted by timeline when out-of-order logging shows up.
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Yes, that's exactly what it is. I'll see if i can improve the naming/docs.
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This new and improved `re_format_arrow` ™️ brings two major improvements: - It is now designed to format standard Arrow dataframes (aka chunks or batches), i.e. a `Schema` and a `Chunk`. In particular: chunk-level and field-level schema metadata will now be rendered properly with the rest of the table. - Tables larger than your terminal will now do their best to fit in, while making sure to still show just enough data. E.g. here's an excerpt of a real-world Rerun dataframe from our `helix` example: ``` cargo r -p rerun-cli --no-default-features --features native_viewer -- print helix.rrd --verbose ``` before (`main`):  and after:  --- Part of a PR series to implement our new chunk-based data model on the client-side (SDKs): - #6437 - #6438 - #6439 - #6440 - #6441
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…6438) Introduces the new `re_chunk` crate: > A chunk of Rerun data, encoded using Arrow. Used for logging, transport, storage and compute. Specifically, it introduces the `Chunk` type itself, and all methods and helpers related to sorting. A `Chunk` is self-describing: it contains all the data _and_ metadata needed to index it into storage. There are a lot of things that need to be sorted within a `Chunk`, and as such we must make sure to keep track of what is or isn't sorted at all times, to avoid needlessly re-sorting things everytime a chunk changes hands. This necessitates a bunch of sanity checking all over the place to make sure we never end up in undefined states. `Chunk` is not about transport, it's about providing a nice-to-work with representation when manipulating a chunk in memory. Transporting a `Chunk` happens in the next PR. - Fixes #1981 --- Part of a PR series to implement our new chunk-based data model on the client-side (SDKs): - #6437 - #6438 - #6439 - #6440 - #6441
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This is a fork of the old `DataTable` batcher, and works very similarly. Like before, this batcher will micro-batch using both space and time thresholds. There are two main differences: - This batcher maintains a dataframe per-entity, as opposed to the old one which worked globally. - Once a threshold is reached, this batcher further splits the incoming batch in order to fulfill these invariants: ```rust /// In particular, a [`Chunk`] cannot: /// * contain data for more than one entity path /// * contain rows with different sets of timelines /// * use more than one datatype for a given component /// * contain more rows than a pre-configured threshold if one or more timelines are unsorted ``` Most of the code is the same, the real interesting piece is `PendingRow::many_into_chunks`, as well as the newly added tests. - Fixes #4431 --- Part of a PR series to implement our new chunk-based data model on the client-side (SDKs): - #6437 - #6438 - #6439 - #6440 - #6441
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Integrate the new chunk batcher in all SDKs, and get rid of the old one. On the backend, we make sure to deserialize incoming chunks into the old `DataTable`s, so business can continue as usual. Although the new batcher has a much more complicated task with all these sub-splits to manage, it is somehow already more performant than the old one 🤷♂️: ```bash # this branch cargo b -p log_benchmark --release && hyperfine --runs 15 './target/release/log_benchmark --benchmarks points3d_many_individual' Benchmark 1: ./target/release/log_benchmark --benchmarks points3d_many_individual Time (mean ± σ): 4.499 s ± 0.117 s [User: 5.544 s, System: 1.836 s] Range (min … max): 4.226 s … 4.640 s 15 runs # main cargo b -p log_benchmark --release && hyperfine --runs 15 './target/release/log_benchmark --benchmarks points3d_many_individual' Benchmark 1: ./target/release/log_benchmark --benchmarks points3d_many_individual Time (mean ± σ): 4.407 s ± 0.773 s [User: 8.423 s, System: 0.880 s] Range (min … max): 2.997 s … 6.148 s 15 runs ``` Notice the massive difference in user time. --- Part of a PR series to implement our new chunk-based data model on the client-side (SDKs): - #6437 - #6438 - #6439 - #6440 - #6441
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A
TransportChunkis aChunkthat is ready for transport and/or storage.It is very cheap to go from
Chunkto aTransportChunkand vice-versa.A
TransportChunkmaps 1:1 to a native ArrowRecordBatch. It has a stable ABI, and can be cheaply send across process boundaries.arrow2has noRecordBatchtype; we will get one once we migrate toarrow-rs.A
TransportChunkis self-describing: it contains all the data and metadata needed to index it into storage.We rely heavily on chunk-level and field-level metadata to communicate Rerun-specific semantics over the wire, e.g. whether some columns are already properly sorted.
The Arrow metadata system is fairly limited -- it's all untyped strings --, but for now that seems good enough. It will be trivial to switch to something else later, if need be.
DataCell's size (& other metadata) over the wire #1760Chunk#1692RERUN:component_name#3360Component'sDataTypeshould embed its metadata #1696Part of a PR series to implement our new chunk-based data model on the client-side (SDKs):
Chunkand its suffle/sort routines #6438TransportChunk#6439Checklist
mainbuild: rerun.io/viewernightlybuild: rerun.io/viewerTo run all checks from
main, comment on the PR with@rerun-bot full-check.