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f429b5a834
Implementing cursor%ROWTYPE variables, according to the task description. This patch includes a refactoring in how sp_instr_cpush and sp_instr_copen work. This is needed to implement MDEV-10598 later easier, to allow variable declarations go after cursor declarations (which is currently not allowed). Before this patch, sp_instr_cpush worked as a Query_arena associated with the cursor. sp_instr_copen::execute() switched to the sp_instr_cpush's Query_arena when executing the cursor SELECT statement. Now the Query_arena associated with the cursor is stored inside an instance of a new class sp_lex_cursor (a LEX descendand) that contains the cursor SELECT statement. This simplifies the implementation, because: - It's easier to follow the code when everything related to execution of the cursor SELECT statement is stored inside the same sp_lex_cursor object (rather than distributed between LEX and sp_instr_cpush). - It's easier to link an sp_instr_cursor_copy_struct to sp_lex_cursor rather than to sp_instr_cpush. - Also, it allows to perform sp_instr_cursor_copy_struct::exec_core() without having a pointer to sp_instr_cpush, using a pointer to sp_lex_cursor instead. This will be important for MDEV-10598, because sp_instr_cpush will happen *after* sp_instr_cursor_copy_struct. After MDEV-10598 is done, this declaration: DECLARE CURSOR cur IS SELECT * FROM t1; rec cur%ROWTYPE; BEGIN OPEN cur; FETCH cur INTO rec; CLOSE cur; END; will generate about this code: +-----+--------------------------+ | Pos | Instruction | +-----+--------------------------+ | 0 | cursor_copy_struct rec@0 | Points to sp_cursor_lex through m_lex_keeper | 1 | set rec@0 NULL | | 2 | cpush cur@0 | Points to sp_cursor_lex through m_lex_keeper | 3 | copen cur@0 | Points to sp_cursor_lex through m_cursor | 4 | cfetch cur@0 rec@0 | | 5 | cclose cur@0 | | 6 | cpop 1 | +-----+--------------------------+ Notice, "cursor_copy_struct" and "set" will go before "cpush". Instructions at positions 0, 2, 3 point to the same sp_cursor_lex instance.