> Someone has to add V2 data pages to > https://github.com/apache/parquet-site/blob/production/content/en/docs/File%20Format/implementationstatus.md > :)
Your wish is my command: https://github.com/apache/parquet-site/pull/124 As the format grows in popularity and momentum builds to evolve, I feel the content on the parquet.apache.org site could use refreshing / updating. So, while I had the site open, I made some other PRs to scratch various itches (I am absolutely 🎣 for someone to please review 🙏): 1. Add Variant/Geometry/Geography types to implementation status matrix: https://github.com/apache/parquet-site/pull/123 2. Improve introduction / overview, add more links to spec and implementation status: https://github.com/apache/parquet-site/pull/125 Thanks, Andrew On Wed, Oct 22, 2025 at 4:09 AM Antoine Pitrou <[email protected]> wrote: > > Hi Julien, hi all, > > On Mon, 20 Oct 2025 15:14:58 -0700 > Julien Le Dem <[email protected]> wrote: > > > > Another question from me: > > > > Since the goal is to not use compression at all in this case (no ZSTD) > > I'm assuming we would be using either: > > - the Data Page V1 with UNCOMPRESSED in the ColumnMetadata.column > > < > https://github.com/apache/parquet-format/blob/786142e26740487930ddc3ec5e39d780bd930907/src/main/thrift/parquet.thrift#L887 > > > > field. > > - the Data Page V2 with false in the DataPageHeaderV2.is_compressed > > < > https://github.com/apache/parquet-format/blob/786142e26740487930ddc3ec5e39d780bd930907/src/main/thrift/parquet.thrift#L746 > > > > field > > The second helping decide if we can selectively compress some pages if > they > > are less compressed by the > > A few years ago there was a question on the support of the DATA_PAGE_V2 > and > > I was curious to hear a refresh on how that's generally supported in > > Parquet implementations. The is_compressed field was exactly intended to > > avoid block compression when the encoding itself is good enough. > > Someone has to add V2 data pages to > > https://github.com/apache/parquet-site/blob/production/content/en/docs/File%20Format/implementationstatus.md > :) > > C++, Java and Rust support them for sure. I feel like we should > probably default to V2 at some point. > > Also see https://github.com/apache/parquet-java/issues/3344 for Java. > > Regards > > Antoine. > > > > > > Julien > > > > On Mon, Oct 20, 2025 at 11:57 AM Andrew Lamb > <[email protected]> wrote: > > > > > Thanks again Prateek and co for pushing this along! > > > > > > > > > > 1. Design and write our own Parquet-ALP spec so that implementations > > > > know exactly how to encode and represent data > > > > > > 100% agree with this (similar to what was done for ParquetVariant) > > > > > > > 2. I may be missing something, but the paper doesn't seem to > mention > > > non-finite values (such as +/-Inf and NaNs). > > > > > > I think they are handled via the "Exception" mechanism. Vortex's ALP > > > implementation (below) does appear to handle finite numbers[2] > > > > > > > 3. It seems there is a single implementation, which is the one > published > > > > together with the paper. It is not obvious that it will be > > > > maintained in the future, and reusing it is probably not an option > for > > > > non-C++ Parquet implementations > > > > > > My understanding from the call was that Prateek and team re-implemented > > > ALP (did not use the implementation from CWI[3]) but that would be > good to > > > confirm. > > > > > > There is also a Rust implementation of ALP[1] that is part of the > Vortex > > > file format implementation. I have not reviewed it to see if it > deviates > > > from the algorithm presented in the paper. > > > > > > Andrew > > > > > > [1]: > > > > > > > https://github.com/vortex-data/vortex/blob/534821969201b91985a8735b23fc0c415a425a56/encodings/alp/src/lib.rs > > > [2]: > > > > > > > https://github.com/vortex-data/vortex/blob/534821969201b91985a8735b23fc0c415a425a56/encodings/alp/src/alp/compress.rs#L266-L281 > > > [3]: https://github.com/cwida/ALP > > > > > > > > > On Mon, Oct 20, 2025 at 4:47 AM Antoine Pitrou > <[email protected]> wrote: > > > > > > > > > > > Hello, > > > > > > > > Thanks for doing this and I agree the numbers look impressive. > > > > > > > > I would ask if possible for more data points: > > > > > > > > 1. More datasets: you could for example look at the datasets that > were > > > > used to originally evalute BYTE_STREAM_SPLIT (see > > > > https://issues.apache.org/jira/browse/PARQUET-1622 and specifically > > > > the Google Doc linked there) > > > > > > > > 2. Comparison to BYTE_STREAM_SPLIT + LZ4 and BYTE_STREAM_SPLIT + ZSTD > > > > > > > > 3. Optionally, some perf numbers on x86 too, but I expect that ALP > will > > > > remain very good there as well > > > > > > > > > > > > I also have the following reservations towards ALP: > > > > > > > > 1. There is no published official spec AFAICT, just a research paper. > > > > > > > > 2. I may be missing something, but the paper doesn't seem to mention > > > > non-finite values (such as +/-Inf and NaNs). > > > > > > > > 3. It seems there is a single implementation, which is the one > published > > > > together with the paper. It is not obvious that it will be > > > > maintained in the future, and reusing it is probably not an option > for > > > > non-C++ Parquet implementations > > > > > > > > 4. The encoding itself is complex, since it involves a fallback on > > > > another encoding if the primary encoding (which constitutes the real > > > > innovation) doesn't work out on a piece of data. > > > > > > > > > > > > Based on this, I would say that if we think ALP is attractive for us, > > > > we may want to incorporate our own version of ALP with the following > > > > changes: > > > > > > > > 1. Design and write our own Parquet-ALP spec so that implementations > > > > know exactly how to encode and represent data > > > > > > > > 2. Do not include the ALPrd fallback which is a homegrown dictionary > > > > encoding without dictionary reuse accross pages, and instead rely on > a > > > > well-known Parquet encoding (such as BYTE_STREAM_SPLIT?) > > > > > > > > 3. Replace the FOR encoding inside ALP, which aims at compressing > > > > integers efficiently, with our own DELTA_BINARY_PACKED (which has the > > > > same qualities and is already available in Parquet implementations) > > > > > > > > Regards > > > > > > > > Antoine. > > > > > > > > > > > > > > > > On Thu, 16 Oct 2025 14:47:33 -0700 > > > > PRATEEK GAUR <[email protected]> wrote: > > > > > Hi team, > > > > > > > > > > We spent some time evaluating ALP compression and decompression > > > compared > > > > to > > > > > other encoding alternatives like CHIMP/GORILLA and compression > > > techniques > > > > > like SNAPPY/LZ4/ZSTD. We presented these numbers to the community > > > members > > > > > on October 15th in the biweekly parquet meeting. ( I can't seem > to > > > access > > > > > the recording, so please let me know what access rules I need to > get to > > > > be > > > > > able to view it ) > > > > > > > > > > We did this evaluation over some datasets pointed by the ALP paper > and > > > > some > > > > > pointed by the parquet community. > > > > > > > > > > The results are available in the following document > > > > > < > > > > > > > > https://docs.google.com/document/d/1PlyUSfqCqPVwNt8XA-CfRqsbc0NKRG0Kk1FigEm3JOg/edit?tab=t.0 > > > > > > > > > > > : > > > > > > > > > > > > > https://docs.google.com/document/d/1PlyUSfqCqPVwNt8XA-CfRqsbc0NKRG0Kk1FigEm3JOg > > > > > > > > > > > Based on the numbers we see > > > > > > > > > > - ALP is comparable to ZSTD(level=1) in terms of compression > ratio > > > > and > > > > > much better compared to other schemes. (numbers in the sheet > are > > > bytes > > > > > needed to encode each value ) > > > > > - ALP going quite well in terms of decompression speed (numbers > in > > > the > > > > > sheet are bytes decompressed per second) > > > > > > > > > > As next steps we will > > > > > > > > > > - Get the numbers for compression on top of byte stream split. > > > > > - Evaluate the algorithm over a few more datasets. > > > > > - Have an implementation in the arrow-parquet repo. > > > > > > > > > > Looking forward to feedback from the community. > > > > > > > > > > Best > > > > > Prateek and Dhirhan > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
