rapidsai/cudf

[FEA] Add a method to check if row group stats are available

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#17,864 opened on 2025年1月29日

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説明

Is your feature request related to a problem? Please describe. Currently, there isn't a method in predicate_pushdown.cpp (filter_row_groups) to check if row group stats aren't available. Hence, we can't ever set num_surviving_row_groups.after_stats_filter to std::nullopt if stats are unavailable.

Describe the solution you'd like We should figure out a relatively cheaper way to distinguish if row group stats aren't available if possible.

Describe alternatives you've considered We currently build the entire statsAST table in predicate_pushdown and try to filter row groups with it. In case no row groups are filtered, we can't distinguish if this was due to ineffective filter or missing stats.

Additional context Originally posted by @mhaseeb123 in https://github.com/rapidsai/cudf/pull/17594#discussion_r1932968249

コントリビューターガイド

技術スタック
cpp
領域
data
Issue 種別
feature
難度新しい貢献者にとっての実装難度です。1 は非常に小さな変更、5 は専門的な作業です。
3
推定時間経験ある貢献者が調査、実装、テスト、pull request 準備にかけるおおよその時間範囲です。
1-2 days
活動状況Issue が今どれだけ取り組みやすいかを示します。新しい、活発、古い、ブロック中、またはメンテナー入力待ちなどです。
fresh
明確さ期待される変更、受け入れ条件、次の手順がどれだけ明確かを示します。
mostly clear
前提条件
C++ programmingcuDF libraryrow group statistics
初心者向け度初回貢献者にどれだけ取り組みやすいかを 1-100 で推定したスコアです。
40
調査方針
Investigate predicate pushdown.cpp, specifically the filter row groups function and the statsAST table. Look at the discussion in PR #17594 for context on distinguishing missing stats from ineffective filters. Consider implementing a lightweight check, such as tracking whether stats were available during parsing.