Adaptive (runtime, stats-based) conjunct reordering for FilterExec — minimal core [benchmarking]

datafusion/common/src/config.rs

@@ -926,6 +926,17 @@ config_namespace! {
         /// tables with a highly-selective join filter, but is also slightly slower.
         pub enforce_batch_size_in_joins: bool, default = false
 
+        /// (experimental) When enabled, `FilterExec` adaptively reorders the
+        /// conjuncts of a conjunctive predicate at runtime. It measures each
+        /// conjunct's selectivity and evaluation cost on the rows that reach it
+        /// and runs the conjuncts that discard the most rows per unit of CPU
+        /// time first, so cheap-and-selective predicates gate expensive ones.
+        /// Reordering never changes query results (only the evaluation order of
+        /// a conjunction) but can change observable side effects of fallible
+        /// predicates, so it is off by default. Predicates containing volatile
+        /// expressions are never reordered.
+        pub adaptive_filter_reordering: bool, default = false
+
         /// Size (bytes) of data buffer DataFusion uses when writing output files.
         /// This affects the size of the data chunks that are uploaded to remote
         /// object stores (e.g. AWS S3). If very large (>= 100 GiB) output files are being