MariaDB · bsrikanth-mariadb · Jun 4, 2026 · May 29, 2026
diff --git a/mysql-test/main/opt_context_load_stats_basic.result b/mysql-test/main/opt_context_load_stats_basic.result
@@ -355,11 +355,6 @@ select * from t1 where a > 10;
 a	b
 Warnings:
 Warning	4253	Failed to parse saved optimizer context: "file_stat_records" element not present at offset 1380.
-set @opt_context=json_remove(@saved_opt_context_1, '$.list_contexts[0].file_stat_records');
-select * from t1 where a > 10;
-a	b
-Warnings:
-Warning	4253	Failed to parse saved optimizer context: "file_stat_records" element not present at offset 1380.
 set @opt_context=json_remove(@saved_opt_context_1, '$.list_contexts[0].indexes[0].index_name');
 select * from t1 where a > 10;
 a	b

diff --git a/mysql-test/main/opt_context_load_stats_basic.test b/mysql-test/main/opt_context_load_stats_basic.test
@@ -226,9 +226,6 @@ select * from t1 where a > 10;
 set @opt_context=json_remove(@saved_opt_context_1, '$.list_contexts[0].file_stat_records');
 select * from t1 where a > 10;
 
-set @opt_context=json_remove(@saved_opt_context_1, '$.list_contexts[0].file_stat_records');
-select * from t1 where a > 10;
-
 set @opt_context=json_remove(@saved_opt_context_1, '$.list_contexts[0].indexes[0].index_name');
 select * from t1 where a > 10;
 

diff --git a/mysql-test/main/opt_context_replay_basic.result b/mysql-test/main/opt_context_replay_basic.result
@@ -354,4 +354,50 @@ trace like '%foo%'
 select context like '%bar%' from information_schema.optimizer_context;
 context like '%bar%'
 1
+drop table t1;
+#
+# MDEV-39791: Handle count aggregate optimization for replay purpose
+#
+create table t1 (a int primary key, b int not null, c varchar(10));
+insert into t1 select seq, seq%5, concat('a-', seq) from seq_1_to_10;
+set optimizer_record_context=1;
+explain
+select count(a), count(b), count(c) from t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	10	
+select context into dumpfile "../../tmp/dump1.sql"
+from information_schema.optimizer_context;
+set optimizer_record_context=0;
+drop table t1;
+set optimizer_replay_context='opt_context';
+# Same query as above, must have same explain:
+explain
+select count(a), count(b), count(c) from t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	10	
+set optimizer_replay_context='';
+drop table t1;
+create table t1 (a int primary key, b int not null, c varchar(10));
+insert into t1 select seq, seq%5, concat('a-', seq) from seq_1_to_10;
+set optimizer_record_context=1;
+explain
+select count(c) from t1 where b = (select count(b) from t1) or a = (select count(a) from t1);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t1	ALL	PRIMARY	NULL	NULL	NULL	10	Using where
+3	SUBQUERY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Select tables optimized away
+2	SUBQUERY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Select tables optimized away
+select context into dumpfile "../../tmp/dump1.sql"
+from information_schema.optimizer_context;
+set optimizer_record_context=0;
+drop table t1;
+set optimizer_replay_context='opt_context';
+# Same query as above, must have same explain:
+explain
+select count(c) from t1 where b = (select count(b) from t1) or a = (select count(a) from t1);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t1	ALL	PRIMARY	NULL	NULL	NULL	10	Using where
+3	SUBQUERY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Select tables optimized away
+2	SUBQUERY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Select tables optimized away
+set optimizer_replay_context='';
+drop table t1;
 drop database db1;
diff --git a/mysql-test/main/opt_context_replay_basic.test b/mysql-test/main/opt_context_replay_basic.test
@@ -228,5 +228,57 @@ explain select * from t1 where a >'foo' or a < 'bar';
 select trace like '%foo%' from information_schema.optimizer_trace;
 select context like '%bar%' from information_schema.optimizer_context;
 
+drop table t1;
+
+--echo #
+--echo # MDEV-39791: Handle count aggregate optimization for replay purpose
+--echo #
+create table t1 (a int primary key, b int not null, c varchar(10));
+insert into t1 select seq, seq%5, concat('a-', seq) from seq_1_to_10;
+
+set optimizer_record_context=1;
+
+explain
+select count(a), count(b), count(c) from t1;
+select context into dumpfile "../../tmp/dump1.sql"
+from information_schema.optimizer_context;
+set optimizer_record_context=0;
+drop table t1;
+--disable_query_log
+--disable_result_log
+--source "$MYSQLTEST_VARDIR/tmp/dump1.sql"
+--enable_query_log
+--enable_result_log
+set optimizer_replay_context='opt_context';
+--echo # Same query as above, must have same explain:
+explain
+select count(a), count(b), count(c) from t1;
 
+set optimizer_replay_context='';
+drop table t1;
+--remove_file "$MYSQLTEST_VARDIR/tmp/dump1.sql"
+
+create table t1 (a int primary key, b int not null, c varchar(10));
+insert into t1 select seq, seq%5, concat('a-', seq) from seq_1_to_10;
+
+set optimizer_record_context=1;
+explain
+select count(c) from t1 where b = (select count(b) from t1) or a = (select count(a) from t1);
+select context into dumpfile "../../tmp/dump1.sql"
+from information_schema.optimizer_context;
+set optimizer_record_context=0;
+drop table t1;
+--disable_query_log
+--disable_result_log
+--source "$MYSQLTEST_VARDIR/tmp/dump1.sql"
+--enable_query_log
+--enable_result_log
+set optimizer_replay_context='opt_context';
+--echo # Same query as above, must have same explain:
+explain
+select count(c) from t1 where b = (select count(b) from t1) or a = (select count(a) from t1);
+
+set optimizer_replay_context='';
+--remove_file "$MYSQLTEST_VARDIR/tmp/dump1.sql"
+drop table t1;
 drop database db1;
diff --git a/sql/opt_context_store_replay.cc b/sql/opt_context_store_replay.cc
@@ -308,9 +308,9 @@ void dump_records_in_range_calls(List<records_in_range_call_record> *rir_list,
   }
 }
 
-static
-void dump_recorded_table_calls(THD *thd, uchar *tbl_name, size_t tbl_name_len,
-                               Json_writer *ctx_writer)
+static void dump_recorded_table_calls(THD *thd, uchar *tbl_name,
+                                      size_t tbl_name_len,
+                                      Json_writer *ctx_writer)
 {
   table_context_for_store *table_context=
       thd->opt_ctx_recorder->search(tbl_name, tbl_name_len);
@@ -1679,10 +1679,10 @@ bool Optimizer_context_replay::infuse_index_read_cost(const TABLE *tbl,
     }
   }
 
-  String warn_msg;
+  String warn_msg(256);
   warn_msg.append(tbl_name);
   warn_msg.append(STRING_WITH_LEN(" with key_number:"));
-  warn_msg.append(keynr);
+  warn_msg.q_append(keynr);
   warn_msg.append(STRING_WITH_LEN(", records:"));
   warn_msg.q_append_int64(records);
   warn_msg.append(STRING_WITH_LEN(", eq_ref:"));
@@ -1801,10 +1801,10 @@ bool Optimizer_context_replay::infuse_records_in_range(
     }
   }
 
-  String warn_msg;
+  String warn_msg(256);
   warn_msg.append(tbl_name);
   warn_msg.append(STRING_WITH_LEN(" with key_number:"));
-  warn_msg.append(keynr);
+  warn_msg.q_append(keynr);
   warn_msg.append(STRING_WITH_LEN(" with min_key:"));
   warn_msg.append(min_key);
   warn_msg.append(STRING_WITH_LEN(" with max_key:"));

diff --git a/sql/opt_context_store_replay.h b/sql/opt_context_store_replay.h
@@ -148,8 +148,6 @@ class Optimizer_context_replay
                                const key_range *max_range, ha_rows *records);
 
 private:
-  bool infuse_table_rows(const TABLE *tbl, ha_rows *rows);
-
   THD *thd;
   /*
     Statistics that tables had before we've replaced them with values from

diff --git a/sql/opt_sum.cc b/sql/opt_sum.cc
@@ -78,13 +78,17 @@ static int maxmin_in_range(bool max_fl, Field* field, COND *cond);
     #			Multiplication of number of rows in all tables
 */
 
-static ulonglong get_exact_record_count(List<TABLE_LIST> &tables)
+static ulonglong get_exact_record_count(THD *thd, List<TABLE_LIST> &tables)
 {
   ulonglong count= 1;
   TABLE_LIST *tl;
   List_iterator<TABLE_LIST> ti(tables);
   while ((tl= ti++))
   {
+    if (thd->opt_ctx_replay)
+    {
+      thd->opt_ctx_replay->infuse_table_rows(tl->table);
+    }
     ha_rows tmp= tl->table->file->records();
     if (tmp == HA_POS_ERROR)
       return ULONGLONG_MAX;
@@ -366,7 +370,7 @@ int opt_sum_query(THD *thd,
         {
           if (!is_exact_count)
           {
-            if ((count= get_exact_record_count(tables)) == ULONGLONG_MAX)
+            if ((count= get_exact_record_count(thd, tables)) == ULONGLONG_MAX)
             {
               /* Error from handler in counting rows. Don't optimize count() */
               const_result= 0;