From acc3517e9047b31e1c13ecd8c71c8d220d03bf6d Mon Sep 17 00:00:00 2001
From: boris <shuaibo.zhang@hotmail.com>
Date: Sat, 29 Aug 2026 21:08:42 +0800
Subject: [PATCH] =?UTF-8?q?=E5=8A=A0=E9=80=9F=E6=97=A5=E5=BA=A6=E8=A1=8C?=
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---
 crates/fidc-core/src/data.rs | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/crates/fidc-core/src/data.rs b/crates/fidc-core/src/data.rs
index 44e1cda..863b24c 100644
--- a/crates/fidc-core/src/data.rs
+++ b/crates/fidc-core/src/data.rs
@@ -566,7 +566,9 @@ struct SymbolPriceSeries {
     valid_volume_start_by_count: Vec<usize>,
 }
 
-type DenseRowPositionIndex = BTreeMap<NaiveDate, Vec<u32>>;
+// Row groups keep their chronological BTreeMap for range scans, while the
+// hot symbol-id lookup uses a hash index to avoid a tree traversal per row.
+type DenseRowPositionIndex = AHashMap<NaiveDate, Vec<u32>>;
 
 const MISSING_ROW_POSITION: u32 = u32::MAX;
 const MAX_DENSE_ROW_INDEX_BYTES: usize = 256 * 1024 * 1024;
@@ -4062,7 +4064,7 @@ fn build_dense_row_positions<T>(
         return None;
     }
 
-    let mut positions_by_date = BTreeMap::new();
+    let mut positions_by_date = AHashMap::new();
     for (date, rows) in groups {
         let symbol_ids = symbol_ids_by_date.get(date)?;
         if rows.len() != symbol_ids.len() {