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https://issues.apache.org/jira/browse/PARQUET-1950?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17742169#comment-17742169
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ASF GitHub Bot commented on PARQUET-1950:
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jaychia commented on PR #164:
URL: https://github.com/apache/parquet-format/pull/164#issuecomment-1631470875
I've been doing more digging into parquet-format and versioning of the spec
has definitely been one of the more confusing pieces. I'm glad that there is an
effort to define "core" features, or feature presets.
I made a simple tool that just reads Parquet files and produces a boolean
checklist of features that are being used in each file:
https://github.com/Eventual-Inc/parquet-benchmarking. Running a tool like this
on "data in the wild" has been our approach so far for understanding what
features are actively being used by the main Parquet producers (Arrow, Spark,
Trino, Impala etc).
It could be useful for developers of Parquet-producing frameworks to start
producing Parquet read/write feature compatibility documentation. As a
community we can then start to understand which features have been actively
adopted and which ones should be considered more experimental or specific to a
given framework!
> Define core features / compliance level
> ---------------------------------------
>
> Key: PARQUET-1950
> URL: https://issues.apache.org/jira/browse/PARQUET-1950
> Project: Parquet
> Issue Type: New Feature
> Components: parquet-format
> Reporter: Gabor Szadovszky
> Assignee: Gabor Szadovszky
> Priority: Major
>
> Parquet format is getting more and more features while the different
> implementations cannot keep the pace and left behind with some features
> implemented and some are not. In many cases it is also not clear if the
> related feature is mature enough to be used widely or more an experimental
> one.
> These are huge issues that makes hard ensure interoperability between the
> different implementations.
> The following idea came up in a
> [discussion|https://lists.apache.org/thread.html/rde5cba8443487bccd47593ddf5dfb39f69c729d260165cb936a1a289%40%3Cdev.parquet.apache.org%3E].
> Create a now document in the parquet-format repository that lists the "core
> features". This document is versioned by the parquet-format releases. This
> way a certain version of "core features" defines a level of compatibility
> between the different implementations. This version number can be written to
> a new field (e.g. complianceLevel) in the footer. If an implementation writes
> a file with a version in the field it must implement all the related "core
> features" (read and write) and must not use any other features at write
> because it makes the data unreadable by another implementation if only the
> same level of "core features" are implemented.
> For example if we have encoding A listed in the version 1 "core features" but
> encoding B is not then at "complianceLevel = 1" we can use encoding A but we
> cannot use encoding B because it would make the related data unreadable.
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