代码版本：mysql 8.0.22

编程语言：c++ && c++11 && c++14 && c++17

上一篇文章：mysql 8.0 一条insert语句的具体执行流程分析(二)_一缕阳光的博客-CSDN博客

主要介绍了存储引擎部分，这个章节主要介绍insert一条语句时有二级索引时需要调用哪些接口，调用接口的顺序如下：

下面的接口基本上看源码就能理解，不再重述。

下面以聚集索引和二级索引为例，聚集索引调用接口如下：

| > row_ins_clust_index_entry
| | > row_ins_clust_index_entry_low
| | | > btr_cur_optimistic_insert
| | | | > btr_cur_ins_lock_and_undo
| | | | | > trx_undo_report_row_operation
| | | | | | > trx_undo_page_report_insert
| | | | | | | > trx_undo_page_set_next_prev_and_add
| | | | | | | | > trx_undof_page_add_undo_rec_log| | | | > page_cur_tuple_insert
| | | | | > rec_convert_dtuple_to_rec> rec_convert_dtuple_to_rec_new> rec_convert_dtuple_to_rec_old> rec_convert_dtuple_to_rec_comp| | | | | > page_cur_insert_rec_low> page_cur_insert_rec_write_log

(12)、row_ins_clust_index_entry : 插入entry到一个聚集索引，会调用13中的接口
(13)、row_ins_clust_index_entry_low : 尝试将entry插入到聚集索引中，忽略外键约束。
(14)、btr_cur_optimistic_insert : 插入一个page到一个索引tree
(15)、btr_cur_ins_lock_and_undo : 检查lock和写undo log
(16)、page_cur_tuple_insert : 将一条record追加到当前page，需要与17中的函数完成
(17)、page_cur_insert_rec_low : 将一条record追加到当前page，以非压缩方式写入

二级索引调用接口如下：

| > row_ins_sec_index_entry
| | > row_ins_sec_index_entry_low
| | | > btr_cur_search_to_nth_level> ibuf_should_try
| | | > row_ins_scan_sec_index_for_duplicate

(18)、row_ins_sec_index_entry : 在二级索引中插入entry
(19)、row_ins_sec_index_entry_low : 尝试将entry插入二级索引。如果找到一个字段完全相同的记录，则必须将另一个记录标记为已删除，然后再插入到二级索引中
(20)、btr_cur_search_to_nth_level : 在索引tree中给定的level上找到当前位置
(21)、row_ins_scan_sec_index_for_duplicate : 扫描给定索引项处的唯一非聚集索引，以确定该项的键值是否发生唯一性冲突。对可能重复的记录设置共享锁

最后，所有断点都被执行之后，使用bt命令将堆栈信息打印出来，由于断点太多了，打印了主要的一些函数，如下：

(gdb) bt
#0  btr_cur_optimistic_insert (flags=0, cursor=0x7fffe83d4ae0, offsets=0x7fffe83d4a78, heap=0x7fffe83d4a70, entry=0x7fff300cb370, rec=0x7fffe83d4a80, big_rec=0x7fffe83d4a68, thr=0x7fff3029c6f8, mtr=0x7fffe83d50a0)at /storage/innobase/btr/btr0cur.cc:2833
#1  0x000055555a4c7571 in row_ins_clust_index_entry_low (flags=0, mode=2, index=0x7fff3028a640, n_uniq=1, entry=0x7fff300cb370, thr=0x7fff3029c6f8, dup_chk_only=false)at storage/innobase/row/row0ins.cc:2518
#2  0x000055555a4c945c in row_ins_clust_index_entry (index=0x7fff3028a640, entry=0x7fff300cb370, thr=0x7fff3029c6f8, dup_chk_only=false)at /storage/innobase/row/row0ins.cc:3097
#3  0x000055555a4c9c14 in row_ins_index_entry (index=0x7fff3028a640, entry=0x7fff300cb370, multi_val_pos=@0x7fff3029c3f8: 0, thr=0x7fff3029c6f8)at /storage/innobase/row/row0ins.cc:3289
#4  0x000055555a4ca26f in row_ins_index_entry_step (node=0x7fff3029c338, thr=0x7fff3029c6f8)at /storage/innobase/row/row0ins.cc:3425
#5  0x000055555a4ca616 in row_ins (node=0x7fff3029c338, thr=0x7fff3029c6f8)at /storage/innobase/row/row0ins.cc:3544
#6  0x000055555a4caa92 in row_ins_step (thr=0x7fff3029c6f8)at /storage/innobase/row/row0ins.cc:3668
#7  0x000055555a4ea804 in row_insert_for_mysql_using_ins_graph (mysql_rec=0x7fff302892c8 "\376\005", prebuilt=0x7fff3029b830) at /storage/innobase/row/row0mysql.cc:1581
#8  0x000055555a4eae9a in row_insert_for_mysql (mysql_rec=0x7fff302892c8 "\376\005", prebuilt=0x7fff3029b830) at /storage/innobase/row/row0mysql.cc:1711
#9  0x000055555a2a9ad9 in ha_innobase::write_row (this=0x7fff30287bf8, record=0x7fff302892c8 "\376\005")at /storage/innobase/handler/ha_innodb.cc:8629
#10 0x0000555558d4ace2 in handler::ha_write_row (this=0x7fff30287bf8, buf=0x7fff302892c8 "\376\005")at /sql/handler.cc:7831
#11 0x00005555590a14a7 in write_record (thd=0x7fff30001040, table=0x7fff30287270, info=0x7fffe83d64f0, update=0x7fffe83d6570) at /sql/sql_insert.cc:2148
#12 0x000055555909cb7e in Sql_cmd_insert_values::execute_inner (this=0x7fff302becc8, thd=0x7fff30001040)at /sql/sql_insert.cc:633
#13 0x00005555589ff8fc in Sql_cmd_dml::execute (this=0x7fff302becc8, thd=0x7fff30001040)at /sql/sql_select.cc:612
#14 0x000055555897bd6e in mysql_execute_command (thd=0x7fff30001040, first_level=true)at /sql/sql_parse.cc:3420
#15 0x00005555589810b9 in dispatch_sql_command (thd=0x7fff30001040, parser_state=0x7fffe83d7b90)at /sql/sql_parse.cc:4988
#16 0x0000555558977226 in dispatch_command (thd=0x7fff30001040, com_data=0x7fffe83d8b80, command=COM_QUERY) at /sql/sql_parse.cc:1836
#17 0x00005555589756df in do_command (thd=0x7fff30001040)at /sql/sql_parse.cc:1320
#18 0x0000555558b6ee3d in handle_connection (arg=0x55556006bbe0)at /sql/conn_handler/connection_handler_per_thread.cc:301
#19 0x000055555aa337b6 in pfs_spawn_thread (arg=0x55555fee7ae0)at /storage/perfschema/pfs.cc:2900
--Type <RET> for more, q to quit, c to continue without paging--
#20 0x00007ffff7f95609 in start_thread (arg=<optimized out>) at pthread_create.c:477
#21 0x00007ffff76e0293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

到此为止，在MySQL中insert一条record的基本过程已经梳理完毕，流程还是比较清晰的，有数据库初级经验的基本都能理清楚。

接下来几篇文章主要讲述MySQL中redo.log中的mtr。