commit c29fc13e183221ecb88ebafd46a9431422fdb2f7
Author: Martin Hansson <martin.hansson@percona.com>
Date:   Tue Dec 9 09:36:04 2025 +0000

    PS-10232 [8.0]: MySQL 8.0.40+ is about 2-3x times slower than 8.0.39 in
    particular index scan scenario
    
    A follow up fix for "Bug#36775910: Record buffer not set in index range scans"
    [2969af5] caused a performance regression by failing to respect the handler's
    recommendation to cap the number of rows in the record buffer (at the time of
    writing hard-coded to 100 for InnoDB). This caused a performance regression
    which is most pronounced when using a small LIMIT.
    
    Fixed by re-introducing the line implementing cap.

diff --git a/sql/sql_executor.cc b/sql/sql_executor.cc
index a905c1f0b50..ebfeb786184 100644
--- a/sql/sql_executor.cc
+++ b/sql/sql_executor.cc
@@ -741,6 +741,9 @@ bool set_record_buffer(TABLE *table, double expected_rows_to_fetch) {
     }
   }
 
+  // Do not allocate space for more rows than the handler asked for.
+  rows_in_buffer = std::min(rows_in_buffer, max_rows);
+
   // After adjustments made above, we still need a minimum of 2 rows to
   // use a record buffer.
   if (rows_in_buffer <= 1) {