alamb commented on code in PR #15301:
URL: https://github.com/apache/datafusion/pull/15301#discussion_r2021602649
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datafusion/common/src/config.rs:
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@@ -590,6 +590,13 @@ config_namespace! {
/// during aggregations, if possible
pub enable_topk_aggregation: bool, default = true
+ /// When set to true attempts to push down dynamic filters generated
by operators into the file scan phase.
+ /// For example, for a query such as `SELECT * FROM t ORDER BY
timestamp DESC LIMIT 10`, the optimizer
+ /// will attempt to push down the current top 10 timestamps that the
TopK operator references into the file scans.
+ /// This means that if we already have 10 timestamps in the year 2025
+ /// any files that only have timestamps in the year 2024 can be
skipped / pruned at various stages in the scan.
Review Comment:
this is a great example
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