MySQL Update执行流程解读
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一、update跟踪执行配置
使用内部程序堆栈跟踪工具path_viewer，跟踪mysql update 一行数据的执行过程, 配置执行脚本：call_update.sh
DROP DATABASE IF EXISTS d1;
CREATE DATABASE d1;
use d1;
drop table if exists test;
CREATE TABLE test (c0 int NOT NULL AUTO_INCREMENT,c1 date DEFAULT NULL,c2 time DEFAULT NULL,
c3 datetime DEFAULT NULL,
c4 year DEFAULT NULL,
c5 int DEFAULT NULL,
c6 decimal(10,6) DEFAULT NULL,
c7 double DEFAULT NULL,
c8 float DEFAULT NULL,
c9 varchar(255) DEFAULT NULL,
PRIMARY KEY (c0)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;
INSERT INTO test VALUES ('1', '2021-04-26', '15:36:37', NULL, '2021', NULL, '6.000000', '7.1', '118.169', 'a8.168111');
INSERT INTO test VALUES ('2', '2021-04-28', '15:36:37', '2021-04-27 15:36:41', '2021', '6', '7877.126000', '8.1', '119.187', 'a9.16');
INSERT INTO test VALUES ('3', '2021-04-29', '15:36:37', '2021-04-27 15:36:41', '2021', '6', '7877.126890', '8.1', '119.187', 'a9.1682');
INSERT INTO test VALUES ('4', '2021-04-30', '15:36:37', '2021-04-27 15:36:41', '2021', '6', '7877.126890', '8.1', '119.187', 'a9.168333');
EOF
sleep 1
mysql -h127.0.0.1 -P3300 -uroot <<EOF
use d1;
\\! ./util/start_trace.sh
update test set c7=10.1 where c0=1;
\\! ./util/end_trace.sh
EOF
# analyse the data
./util/seperate.sh $TOPIC 10000 5
~执行后，生成执行结果：
path_viewer/call_update$ ls
362688_5.txt 362689.dat 362690.inf 362692_5.txt 362699.dat 362706.inf 362717_L.txt mark.txt
362688.dat 362689.inf 362691_5.txt 362692.dat 362699.inf 362717_5.txt 362717_M.txt TDATA.trc
362688.inf 362690_5.txt 362691.dat 362692.inf 362706_5.txt 362717.dat 362717_S.txt THREADS.inf
362689_5.txt 362690.dat 362691.inf 362699_5.txt 362706.dat 362717.inf FUNC_DEF查看SQL执行的函数调用过程362717_5.txt
> my_net_set_read_timeout(NET*, unsigned int)
> vio_timeout(Vio*, unsigned int, int)
> vio_socket_timeout(Vio*, unsigned int, bool)
< vio_socket_timeout(Vio*, unsigned int, bool)
< vio_timeout(Vio*, unsigned int, int)
< my_net_set_read_timeout(NET*, unsigned int)
> dispatch_command(THD*, COM_DATA const*, enum_server_command)
> PROFILING::start_new_query(char const*)
< PROFILING::start_new_query(char const*)
> inline_mysql_refine_statement(PSI_statement_locker*, unsigned int)
> pfs_refine_statement_v2(PSI_statement_locker*, unsigned int)
> find_statement_class(unsigned int)
< find_statement_class(unsigned int)
< pfs_refine_statement_v2(PSI_statement_locker*, unsigned int)
< inline_mysql_refine_statement(PSI_statement_locker*, unsigned int)
> THD::set_command(enum_server_command)
> pfs_set_thread_command_vc(int)
< pfs_set_thread_command_vc(int)
< THD::set_command(enum_server_command)
> THD::clear_slow_extended()
> inline_mysql_mutex_unlock(mysql_mutex_t*, char const*, unsigned int)
> my_mutex_unlock(my_mutex_t*)
> native_mutex_unlock(pthread_mutex_t*)
< native_mutex_unlock(pthread_mutex_t*)
< my_mutex_unlock(my_mutex_t*)
< inline_mysql_mutex_unlock(mysql_mutex_t*, char const*, unsigned int)
< THD::clear_slow_extended().................................
< MYSQLparse(THD*, Parse_tree_root**)
> LEX::make_sql_cmd(Parse_tree_root*)
> PT_update::make_cmd(THD*)
> Parse_context::Parse_context(THD*, Query_block*)
< Parse_context::Parse_context(THD*, Query_block*)
> bool (anonymous namespace)::contextualize_safe<Parse_context, PT_with_clause*>(Parse_context*, PT_with_clause*)
< bool (anonymous namespace)::contextualize_safe<Parse_context, PT_with_clause*>(Parse_context*, PT_with_clause*)
> PT_table_factor_table_ident::contextualize(Parse_context*)
> Query_block::add_table_to_list(THD*, Table_ident*, char const*, unsigned long, thr_lock_type, enum_mdl_type, List<Index_hint>*, List<String>*, MYSQL_LEX_STRING*, Parse_context*)
> check_table_name(char const*, unsigned long)
< check_table_name(char const*, unsigned long)
> memdup_root(MEM_ROOT*, void const*, unsigned long)
.................................
> Sql_cmd_dml::execute(THD*)
> is_timer_applicable_to_statement(THD*)
< is_timer_applicable_to_statement(THD*)
> THD::push_internal_handler(Internal_error_handler*)
< THD::push_internal_handler(Internal_error_handler*)
> Sql_cmd_dml::prepare(THD*)
> Sql_cmd_update::precheck(THD*)
> check_one_table_access(THD*, unsigned long, TABLE_LIST*)
> check_single_table_access(THD*, unsigned long, TABLE_LIST*, bool)
> check_access(THD*, unsigned long, char const*, unsigned long*, GRANT_INTERNAL_INFO*, bool, bool)
> get_cached_schema_access(GRANT_INTERNAL_INFO*, char const*)
> ACL_internal_schema_registry::lookup(char const*)
< ACL_internal_schema_registry::lookup(char const*).................................
< THD::is_dml_gtid_compatible(bool, bool, bool)
< THD::decide_logging_format(TABLE_LIST*)
< lock_tables(THD*, TABLE_LIST*, unsigned int, unsigned int)
> Sql_cmd_update::execute_inner(THD*)
> Sql_cmd_update::update_single_table(THD*)
> Query_expression::set_limit(THD*, Query_block*)
> Query_block::get_offset(THD*)
< Query_block::get_offset(THD*)
> Query_block::get_limit(THD*)
< Query_block::get_limit(THD*)
< Query_expression::set_limit(THD*, Query_block*)
> COPY_INFO::get_function_default_columns(TABLE*)
> allocate_column_bitmap(TABLE*, MY_BITMAP**)
> multi_alloc_root(MEM_ROOT*, ...)
< multi_alloc_root(MEM_ROOT*, ...)
< allocate_column_bitmap(TABLE*, MY_BITMAP**)
> bitmap_is_clear_all(MY_BITMAP const*)
< bitmap_is_clear_all(MY_BITMAP const*).................................
> handler::ha_fast_update(THD*, mem_root_deque<Item*>&, mem_root_deque<Item*>&, Item*)
< handler::ha_fast_update(THD*, mem_root_deque<Item*>&, mem_root_deque<Item*>&, Item*)
> IndexRangeScanIterator::Read()
> QUICK_RANGE_SELECT::get_next()
> handler::ha_multi_range_read_next(char**)
> ha_innobase::multi_range_read_next(char**)> DsMrr_impl::dsmrr_next(char**)
> handler::multi_range_read_next(char**)
> quick_range_seq_next(void*, KEY_MULTI_RANGE*)
< quick_range_seq_next(void*, KEY_MULTI_RANGE*)
> ha_innobase::read_range_first(key_range const*, key_range const*, bool, bool)
> handler::read_range_first(key_range const*, key_range const*, bool, bool).................................
> handler::ha_update_row(unsigned char const*, unsigned char*)
> handler::mark_trx_read_write()
< handler::mark_trx_read_write()
> pfs_start_table_io_wait_v1(PSI_table_locker_state*, PSI_table*, PSI_table_io_operation, unsigned int, char const*, unsigned int)
< pfs_start_table_io_wait_v1(PSI_table_locker_state*, PSI_table*, PSI_table_io_operation, unsigned int, char const*, unsigned int)
> ha_innobase::update_row(unsigned char const*, unsigned char*)
> handler::ha_statistic_increment(unsigned long long System_status_var::*) const
< handler::ha_statistic_increment(unsigned long long System_status_var::*) const
> row_get_prebuilt_update_vector(row_prebuilt_t*)
> row_create_update_node_for_mysql(dict_table_t*, mem_block_info_t*)
> upd_node_create(mem_block_info_t*)
> mem_heap_zalloc(mem_block_info_t*, unsigned long)
> mem_heap_alloc(mem_block_info_t*, unsigned long)
> mem_block_get_len(mem_block_info_t*)
< mem_block_get_len(mem_block_info_t*)
> mem_block_get_free(mem_block_info_t*)
< mem_block_get_free(mem_block_info_t*)
> mem_block_get_free(mem_block_info_t*)
< mem_block_get_free(mem_block_info_t*)
> mem_block_set_free(mem_block_info_t*, unsigned long)
< mem_block_set_free(mem_block_info_t*, unsigned long)
< mem_heap_alloc(mem_block_info_t*, unsigned long)
< mem_heap_zalloc(mem_block_info_t*, unsigned long)
> mem_heap_create_func(unsigned long, unsigned long).................................
> __gnu_cxx::__exchange_and_add(int volatile*, int)
< __gnu_cxx::__exchange_and_add(int volatile*, int)
< __gnu_cxx::__exchange_and_add_dispatch(int*, int)
< QUICK_RANGE_SELECT::~QUICK_RANGE_SELECT()
< QUICK_RANGE_SELECT::~QUICK_RANGE_SELECT()
< QEP_shared_owner::qs_cleanup()
< QEP_TAB::cleanup()
< Sql_cmd_update::update_single_table(THD*)
< Sql_cmd_update::execute_inner(THD*)
> THD::pop_internal_handler()
< THD::pop_internal_handler()
> Query_expression::cleanup(THD*, bool)
> Query_block::cleanup(THD*, bool)
< Query_block::cleanup(THD*, bool)
< Query_expression::cleanup(THD*, bool)二、执行分析
主要过程函数
do_command(THD*) --从连接中读取命令
dispatch_sql_command --分发命令
THD::sql_parser() --SQL引擎层，词法语法分析
parse_sql --SQL转换为AST语句
LEX::make_sql_cmd(Parse_tree_root*) --解析树翻译成AST语法树
PT_update::make_cmd(THD*) --生成命令对象，包含上下文处理
mysql_execute_command --命令执行
Sql_cmd_dml::execute
Sql_cmd_dml::prepare(THD*) --引用消解
Sql_cmd_update::precheck(THD*) --更新语句实际执行的引用消解
Sql_cmd_update::execute_inner(THD*) --SQL引擎层，调用存储引擎接口执行
Sql_cmd_update::update_single_table(THD*)
optimize_cond --执行优化器优化路径
handler::ha_fast_update
ha_innobase::update_row --innodb更新buffer pool 中table 的row
trans_commit_stmt(THD*, bool)innoDB关键更新执行过程
ha_innobase::update_row：
row_get_prebuilt_update_vector
calc_row_difference
row_update_for_mysql
row_upd_step
row_upd --执行更新
btr_pcur_t::restore_position
rec_get_offsets_func
btr_cur_update_in_place
btr_cur_upd_lock_and_undo
trx_undo_report_row_operation
trx_undo_create
trx_undo_seg_create
_fil_io
Fil_shard::do_io
pfs_os_aio_func
mtr_t::Command::execute
log_buffer_reserve
mtr_t::Command::add_dirty_blocks_to_flush_list ---脏数据快准备刷入磁盘
trx_undo_page_report_modify
row_upd_rec_sys_fields
row_upd_rec_in_place
btr_cur_update_in_place_log更新过程描述:
InnoDB 存储引擎，当更新一条数据时，会先更新 buffer pool 中的数据，Master Thread 刷新缓冲池中的脏页数据到磁盘中；更新一条记录前，会先生成一条undolog，记录更新操作，再生成redolog；事务提交时，将事务生成的redolog刷入磁盘。
三、执行总结
update执行流程
1.执行语句连接数据库
2.分析器通过词法、语法分析知道这是一条更新语句
3.优化器确定执行路径
4.执行器具体执行，找到这一行，更新数据，然后通过Inodb存储具体更新操作
5.InnoDB 存储引擎更新内存数据后写入磁盘，过程中会更新各个日志文件binlog、undolog、redolog
Enjoy GreatSQL :)
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