From 9020baf126c7d4068b40c57bc2d7dcb747b4b341 Mon Sep 17 00:00:00 2001
From: Sergei Petrunia <sergey@mariadb.com>
Date: Sat, 24 Aug 2024 19:01:06 +0300
Subject: [PATCH] Trivial fix: Make test_if_cheaper_ordering() use
 actual_rec_per_key()

Discovered this while working on MDEV-34720: test_if_cheaper_ordering()
uses rec_per_key, while the original estimate for the access method
is produced in best_access_path() by using actual_rec_per_key().

Make test_if_cheaper_ordering() also use actual_rec_per_key().
Also make several getter function "const" to make this compile.
Also adjusted the testcase to handle this (the change backported from
11.0)
---
 mysql-test/main/subselect_innodb.result | 1 +
 mysql-test/main/subselect_innodb.test   | 2 ++
 sql/sql_select.cc                       | 3 ++-
 sql/sql_statistics.h                    | 2 +-
 sql/structs.h                           | 2 +-
 sql/table.cc                            | 2 +-
 6 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/mysql-test/main/subselect_innodb.result b/mysql-test/main/subselect_innodb.result
index ea0affd575f..c8c0fd693f2 100644
--- a/mysql-test/main/subselect_innodb.result
+++ b/mysql-test/main/subselect_innodb.result
@@ -554,6 +554,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 #
 # MDEV-6081: ORDER BY+ref(const): selectivity is very incorrect (MySQL Bug#14338686)
 #
+insert into t2 select seq,seq,seq from seq_10000_to_11000;
 alter table t2 add key2 int;
 update t2 set key2=key1;
 alter table t2 add key(key2);
diff --git a/mysql-test/main/subselect_innodb.test b/mysql-test/main/subselect_innodb.test
index f675dda91b4..12ce5cabbeb 100644
--- a/mysql-test/main/subselect_innodb.test
+++ b/mysql-test/main/subselect_innodb.test
@@ -558,7 +558,9 @@ from
 --echo #
 --echo # MDEV-6081: ORDER BY+ref(const): selectivity is very incorrect (MySQL Bug#14338686)
 --echo #
+--source include/have_sequence.inc
 
+insert into t2 select seq,seq,seq from seq_10000_to_11000;
 alter table t2 add key2 int;
 update t2 set key2=key1;
 alter table t2 add key(key2);
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 176310224a2..d8958041160 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -30391,7 +30391,8 @@ test_if_cheaper_ordering(const JOIN_TAB *tab, ORDER *order, TABLE *table,
     else
     {
       const KEY *ref_keyinfo= table->key_info + ref_key;
-      refkey_rows_estimate= ref_keyinfo->rec_per_key[tab->ref.key_parts - 1];
+      refkey_rows_estimate=
+        (ha_rows)ref_keyinfo->actual_rec_per_key(tab->ref.key_parts - 1);
     }
     set_if_bigger(refkey_rows_estimate, 1);
   }
diff --git a/sql/sql_statistics.h b/sql/sql_statistics.h
index 166e7a75c79..6d7dd3618ff 100644
--- a/sql/sql_statistics.h
+++ b/sql/sql_statistics.h
@@ -472,7 +472,7 @@ public:
 
   bool avg_frequency_is_inited() { return avg_frequency != NULL; }
 
-  double get_avg_frequency(uint i)
+  double get_avg_frequency(uint i) const
   {
     return (double) avg_frequency[i] / Scale_factor_avg_frequency;
   }
diff --git a/sql/structs.h b/sql/structs.h
index 1641b8b3cbd..76ae013ca3b 100644
--- a/sql/structs.h
+++ b/sql/structs.h
@@ -166,7 +166,7 @@ typedef struct st_key {
   engine_option_value *option_list;
   ha_index_option_struct *option_struct;                  /* structure with parsed options */
 
-  double actual_rec_per_key(uint i);
+  double actual_rec_per_key(uint i) const;
 
   bool without_overlaps;
   /*
diff --git a/sql/table.cc b/sql/table.cc
index 373c70c5983..60345ac5a21 100644
--- a/sql/table.cc
+++ b/sql/table.cc
@@ -10034,7 +10034,7 @@ uint TABLE_SHARE::actual_n_key_parts(THD *thd)
 }  
 
 
-double KEY::actual_rec_per_key(uint i)
+double KEY::actual_rec_per_key(uint i) const
 { 
   if (rec_per_key == 0)
     return 0;