rapidsai/cudf

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

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#17,864 建立於 2025年1月29日

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描述

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

貢獻者指南

技術棧
cpp
領域
data
議題類型
feature
難度面向新貢獻者的預計實作難度，1 表示很小改動，5 表示專家級工作。
3
預計時間有經驗貢獻者完成調查、實作、測試並準備 pull request 的粗略時間範圍。
1-2 days
活動狀態議題目前的可參與程度：新鮮、活躍、陳舊、阻塞或等待維護者輸入。
fresh
清晰度議題是否清楚說明預期改動、驗收標準和下一步。
mostly clear
前置要求
C++ programmingcuDF libraryrow group statistics
新手友善度1-100 的估計分數，表示該議題對首次貢獻者的友善程度。
40
研究方向
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.