MDEV-34447: Memory leakage is detected on running the test main.ps against the server 11.1
The memory leak happened on second execution of a prepared statement that runs UPDATE statement with correlated subquery in right hand side of the SET clause. In this case, invocation of the method table->stat_records() could return the zero value that results in going into the 'if' branch that handles impossible where condition. The issue is that this condition branch missed saving of leaf tables that has to be performed as first condition optimization activity. Later the PS statement memory root is marked as read only on finishing first time execution of the prepared statement. Next time the same statement is executed it hits the assertion on attempt to allocate a memory on the PS memory root marked as read only. This memory allocation takes place by the sequence of the following invocations: Prepared_statement::execute mysql_execute_command Sql_cmd_dml::execute Sql_cmd_update::execute_inner Sql_cmd_update::update_single_table st_select_lex::save_leaf_tables List<TABLE_LIST>::push_back To fix the issue, add the flag SELECT_LEX::leaf_tables_saved to control whether the method SELECT_LEX::save_leaf_tables() has to be called or it has been already invoked and no more invocation required. Similar issue could take place on running the DELETE statement with the LIMIT clause in PS/SP mode. The reason of memory leak is the same as for UPDATE case and be fixed in the same way.
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