MDEV-16507 SIGSEGV when use_stat_tables = preferably and

           optimizer_use_condition_selectivity = 4

It does not makes sense to try to read statistics for temporary tables
because it's not collected.

mysql-test/r/statistics.result

@@ -1659,3 +1659,23 @@ id
 set use_stat_tables=@save_use_stat_tables;
 set optimizer_use_condition_selectivity= @save_optimizer_use_condition_selectivity;
 drop table t1,t2;
+#
+# MDEV-16507: statistics for temporary tables should not be used
+#
+SET
+@save_optimizer_use_condition_selectivity= @@optimizer_use_condition_selectivity;
+SET @@use_stat_tables = preferably ;
+SET @@optimizer_use_condition_selectivity = 4;
+CREATE TABLE t1 (
+TIMESTAMP TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
+ON UPDATE CURRENT_TIMESTAMP
+);
+SET @had_t1_table= @@warning_count != 0;
+CREATE TEMPORARY TABLE tmp_t1 LIKE t1;
+INSERT INTO tmp_t1 VALUES (now());
+INSERT INTO t1 SELECT * FROM tmp_t1 WHERE @had_t1_table=0;
+DROP TABLE t1;
+SET
+use_stat_tables=@save_use_stat_tables;
+SET
+optimizer_use_condition_selectivity= @save_optimizer_use_condition_selectivity;

mysql-test/t/statistics.test

@@ -737,3 +737,27 @@ set use_stat_tables=@save_use_stat_tables;
 set optimizer_use_condition_selectivity= @save_optimizer_use_condition_selectivity;
 drop table t1,t2;
 
+--echo #
+--echo # MDEV-16507: statistics for temporary tables should not be used
+--echo #
+
+SET
+@save_optimizer_use_condition_selectivity= @@optimizer_use_condition_selectivity;
+SET @@use_stat_tables = preferably ;
+SET @@optimizer_use_condition_selectivity = 4;
+
+CREATE TABLE t1 (
+  TIMESTAMP TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
+  ON UPDATE CURRENT_TIMESTAMP
+);
+
+SET @had_t1_table= @@warning_count != 0;
+CREATE TEMPORARY TABLE tmp_t1 LIKE t1;
+INSERT INTO tmp_t1 VALUES (now());
+INSERT INTO t1 SELECT * FROM tmp_t1 WHERE @had_t1_table=0;
+DROP TABLE t1;
+
+SET
+use_stat_tables=@save_use_stat_tables;
+SET
+optimizer_use_condition_selectivity= @save_optimizer_use_condition_selectivity;

sql/sql_statistics.cc

@@ -2952,7 +2952,7 @@ bool statistics_for_tables_is_needed(THD *thd, TABLE_LIST *tables)
 
   for (TABLE_LIST *tl= tables; tl; tl= tl->next_global)
   {
-    if (!tl->is_view_or_derived() && tl->table)
+    if (!tl->is_view_or_derived() && !is_temporary_table(tl) && tl->table)
     {
       TABLE_SHARE *table_share= tl->table->s;
       if (table_share && 
@@ -2964,7 +2964,7 @@ bool statistics_for_tables_is_needed(THD *thd, TABLE_LIST *tables)
 
   for (TABLE_LIST *tl= tables; tl; tl= tl->next_global)
   {
-    if (!tl->is_view_or_derived() && tl->table)
+    if (!tl->is_view_or_derived() && !is_temporary_table(tl) && tl->table)
     {
       TABLE_SHARE *table_share= tl->table->s;
       if (table_share && 
@@ -3093,7 +3093,7 @@ int read_statistics_for_tables_if_needed(THD *thd, TABLE_LIST *tables)
 
   for (TABLE_LIST *tl= tables; tl; tl= tl->next_global)
   {
-    if (!tl->is_view_or_derived() && tl->table)
+    if (!tl->is_view_or_derived() && !is_temporary_table(tl) && tl->table)
     { 
       TABLE_SHARE *table_share= tl->table->s;
       if (table_share && 
@@ -3867,4 +3867,4 @@ bool is_stat_table(const char *db, const char *table)
     }
   }
   return false;
-}
+}
\ No newline at end of file