从源码编译的mysql服务器，带debug信息，已安装gdb，便于学习和调试mysql功能及源码。
> wget https://raw.githubusercontent.com/leo18945/docker-mysql-debug/master/docker-compose.yml > docker-compose up -d > docker exec -it mysql-debug bash root@1d1e15b4c637:/work#root@1d1e15b4c637:/work# cat /etc/*release PRETTY_NAME="Debian GNU/Linux 10 (buster)" NAME="Debian GNU/Linux" VERSION_ID="10" VERSION="10 (buster)" VERSION_CODENAME=buster ID=debian HOME_URL="https://www.debian.org/" SUPPORT_URL="https://www.debian.org/support" BUG_REPORT_URL="https://bugs.debian.org/"wget https://cdn.mysql.com/archives/mysql-5.7/mysql-boost-5.7.29.tar.gzcmake \ -DCMAKE_INSTALL_PREFIX=/work/mysql \ -DMYSQL_DATADIR=/work/mysql/data \ -DMYSQL_UNIX_ADDR=/work/mysql/tmp/mysql.sock \ -DDEFAULT_CHARSET=utf8mb4 \ -DDEFAULT_COLLATION=utf8mb4_unicode_ci \ -DEXTRA_CHARSETS=all \ -DENABLED_LOCAL_INFILE=1 \ -DDOWNLOAD_BOOST=0 \ -DWITH_BOOST=/work/mysql-5.7.29/boost/boost_1_59_0 \ -DWITH_DEBUG=1 \ -DWITH_EMBEDDED_SERVER=0 \ -DWITH_EMBEDDED_SHARED_LIBRARY=0root@9d80e46284e8:/work# ps aux USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 1 0.0 0.0 996 4 ? Ss 19:45 0:00 /sbin/docker-init -- /work/docker-entrypoint.sh root 8 0.0 0.0 5488 3104 ? S 19:45 0:00 /bin/bash /work/docker-entrypoint.sh mysql 36 0.2 4.9 2186544 211876 ? Sl 19:45 0:00 mysqld --defaults-file=/work/my.cnf --debug --user=mysql root 64 0.0 0.0 5752 3640 pts/0 Ss 19:45 0:00 bash root 82 0.0 0.0 9392 3064 pts/0 R+ 19:49 0:00 ps auxroot@9d80e46284e8:/work# envs BASH_ALIAS=/etc/bash.bashrc; alias ll='ls -laFh'; alias lls='ll -S' BCVIEW_COMMAND=bcview table.ibd 16 94 200 BITNAMI_IMAGE_VERSION=mysql-version: 5.7.29 GDB_BREAKPOINT=gdb breakpoint handle_query do_select do_command JOIN::exec JOIN::get_end_select_func st_select_lex_unit::execute st_select_lex_unit::set_limit st_select_lex_unit::cleanup st_select_lex_unit::first_select Materialized_cursor::send_result_set_metadata JOIN::make_join_plan Optimize_table_order::choose_table_order Optimize_table_order::greedy_search GDB_COMMAND=gdb -p <mysqld-pid> -ex 'p dict_sys->row_id=281474976710656' -batch HOME=/ GDB_LOAD_BREAKPOINT=source /work/mysql-breakpoints.txt HOSTNAME=9d80e46284e8 INNBLOCK_COMMAND=innblock table.ibd scan 16 MYSQL_CHANGE_PASSWORD=set password = password('pass'); MYSQL_CONF_FILE=/etc/my.cnf MYSQL_DATA_DIR=/work/mysql/data MYSQL_GREP_ROOT_PASSWORD=grep 'temporary password' /work/mysql/log/mysqld.log MYSQL_HOME=/work/mysql MYSQL_SOURCE_DIR=/work/mysql-5.7.29 MYSQL_PAGE_COPY_COMMAND=dd if=table.ibd of=new.hex skip=4 bs=16k count=1 MYSQL_START_CLIENT=mysql -u root -p OS_ARCH=amd64 OS_FLAVOUR=debian-10 OS_NAME=linux PATH=/work/mysql/bin:/work:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin PWD=/work SHLVL=1 TERM=xterm _=/usr/bin/env> cat /etc/my.cnf [mysqld] # 不解析客户端主机名，这样就只能在mysql的授权表中对客户端IP授权，不能对主机名授权 skip_name_resolve= true bind_address= 0.0.0.0 port= 3306 max_allowed_packet= 16M explicit_defaults_for_timestamp= 1 # 1-表名等全转为小写存储，查询等也转为小写对比 lower_case_table_names= 1 ############################################################# # 设置mysql运行的各级目录 basedir= /work/mysql datadir= /work/mysql/data tmpdir= /work/mysql/tmp pid_file= /work/mysql/tmp/mysqld.pid socket= /work/mysql/tmp/mysql.sock ############################################################# # 数据库默认字符集，utf8mb4符集支持表情符号（表情符号占4个字节） character_set_server= utf8mb4 collation_server= utf8mb4_unicode_ci # 是否允许客户端设置会话的字符集，此处允许 # skip-character-set-client-handshake = off character-set-client-handshake= on # init_connect = 'SET NAMES utf8mb4' ############################################################# # The locale to use for error messages. The default is en_US. # lc_messages_dir = /work/mysql/share lc_messages= en_US ############################################################# # 开启系统日志 log_error= /work/mysql/log/mysqld.log # 开启查询日志 general_log= on general_log_file= /work/mysql/log/general.log # 开启慢查询日志功能 # slow_query_log = on # slow_query_log_file = /work/mysql/log/slow_query.log # 查询超过多长时间的SQL才会记录到慢查询日志文件(默认时间为10秒) # long_query_time = 10 # log_queries_not_using_indexes = on ############################################################# # 用来限制LOAD DATA, SELECT ... OUTFILE, and LOAD_FILE()传到哪个指定目录的，或者system ls /可以访问哪个目录 secure_file_priv= / # 设置mysql服务器id，为了在使用binlog功能时区分不同的服务器 server-id= 1 # 开启binlog，并设置log_bin_index前缀为mysql-bin log_bin= mysql-bin # 是否信任创建存储过程的创建者，信任他们在创建存储过程时不会修改库中表的数据，否则容易导致主从复制时数据不一致，此处信任 log_bin_trust_function_creators= on [client] port= 3306 socket= /work/mysql/tmp/mysql.sock default_character_set= utf8mb4 [mysql] default-character-set= utf8mb4 socket= /work/mysql/tmp/mysql.sock # https://gist.github.com/rhtyd/d59078be4dc88123104e # https://fromdual.com/mysql-configuration-file-sampleroot@9d80e46284e8:/work# grep 'temporary password' /work/mysql/log/mysqld.log 2021-02-23T12:41:00.778375Z 1 [Note] A temporary password is generated for root@localhost: sfUr7ha2qg,5root@9d80e46284e8:/work# mysql -u root -p Enter password: sfUr7ha2qg,5 Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 2 Server version: 5.7.29-debug mysql> set password = password('pass'); mysql> create database test; mysql> use test; mysql> create table test1(name varchar(20)); mysql> insert into test1 values('AAA'); mysql> select * from test1; +------+ | name | +------+ | AAA | +------+ mysql> create table test2(name varchar(20)); mysql> insert into test2 values('BBB'); mysql> select * from test2; +------+ | name | +------+ | BBB | +------+mysql> system bcview /work/mysql/data/test/test1.ibd 16 94 100 current block:00000003--Offset:00094--cnt bytes:100--data is:010002001c696e66696d756d0002000b000073757072656d756d0300000010fff1000000000200000000000507a70000011b0110414141000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 # block:00000003字节码分析如下 rcd_header row_id trx_id ptr_id name 03 00 000010fff1 000000000200 000000000507 a70000011b0110 414141 mysql> select conv('200', 16, 10); +---------------------+ | conv('200', 16, 10) | +---------------------+ | 512 | +---------------------+ # 可以看出，rowid从512开始mysql> system bcview /work/mysql/data/test/test2.ibd 16 94 100 current block:00000003--Offset:00094--cnt bytes:100--data is:010002001c696e66696d756d0002000b000073757072656d756d0300000010fff100000000020100000000050cac000001200110424242000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 # block:00000003字节码分析如下 rcd_header row_id trx_id ptr_id name 03 00 000010fff1 000000000201 00000000050c ac000001200110 424242 mysql> select conv('201', 16, 10); +---------------------+ | conv('201', 16, 10) | +---------------------+ | 513 | +---------------------+ # 可以看出，rowid从513开始 # 多个表共用一个dict_sys.row_id变量值# 查看使用gdb修改mysql rowid的命令 mysql> system echo $GDB_COMMAND gdb -p <mysqld-pid> -ex 'p dict_sys->row_id=281474976710656' -batch # 使用ps查看mysqld的进程ID mysql> system ps aux | grep 3306 mysql 297 0.1 5.1 2186352 221700 pts/0 Sl 13:07 0:01 /work/mysql/bin/mysqld --basedir=/work/mysql --datadir=/work/mysql/data --plugin-dir=/work/mysql/lib/plugin --user=mysql --log-error=/work/mysql/log/mysqld.log --pid-file=/work/mysql/data/cb76697ed1bf.pid --socket=/work/mysql/tmp/mysql.sock --port=3306 root 371 0.0 0.0 2388 692 pts/0 S+ 13:22 0:00 sh -c ps aux | grep 3306 root 373 0.0 0.0 3084 888 pts/0 S+ 13:22 0:00 grep 3306 # 执行gdb命令修改mysql dict_sys->row_id 的值为10000 # 即没主键的表插入数据时从dict_sys->row_id处取值 mysql> system gdb -p 297 -ex 'p dict_sys->row_id=10000' -batch [New LWP 298] ... [New LWP 346] [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". 0x00007f4b561e2819 in __GI___poll (fds=0x556d880cabd0, nfds=2, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:29 29../sysdeps/unix/sysv/linux/poll.c: No such file or directory. $1 = 10000 [Inferior 1 (process 297) detached]# 再向test1表中插入数据，看新的rowid是多少 mysql> insert into test1 values('CCC'); Query OK, 1 row affected (0.00 sec) mysql> insert into test2 values('DDD'); Query OK, 1 row affected (0.00 sec) # 读取test1表中page3的字节码分析 mysql> system bcview /work/mysql/data/test/test1.ibd 16 94 100 current block:00000003--Offset:00094--cnt bytes:100--data is:010002001c696e66696d756d0003000b000073757072656d756d0300000010001d000000000200000000000507a70000011b01104141410300000018ffd400000000271000000000050dad00000121011043434300000000000000000000000000000000 # block:00000003字节码分析如下 rcd_header row_id trx_id ptr_id name 03 00 000010001d 000000000200 000000000507 a70000011b0110 414141 03 00 000018ffd4 000000002710 00000000050d ad000001210110 434343 mysql> select conv('2710', 16, 10); +----------------------+ | conv('2710', 16, 10) | +----------------------+ | 10000 | +----------------------+ # test1 表已使用新的 rowid mysql> system bcview /work/mysql/data/test/test2.ibd 16 94 100 current block:00000003--Offset:00094--cnt bytes:100--data is:010002001c696e66696d756d0003000b000073757072656d756d0300000010001d00000000020100000000050cac0000012001104242420300000018ffd4000000002711000000000512b000000124011044444400000000000000000000000000000000 # block:00000003字节码分析如下 rcd_header row_id trx_id ptr_id name 03 00 000010001d 000000000201 00000000050c ac000001200110 424242 03 00 000018ffd4 000000002711 000000000512 b0000001240110 444444 mysql> select conv('2711', 16, 10); +----------------------+ | conv('2711', 16, 10) | +----------------------+ | 10001 | +----------------------+ # test2 表已使用新的 rowidCREATE TABLE emp ( empno decimal(4,0) NOT NULL, ename varchar(10), job varchar(9), mgr decimal(4,0), hiredate date, sal decimal(7,2), comm decimal(7,2), deptno decimal(2,0) ); CREATE TABLE dept ( deptno decimal(2,0), dname varchar(14), loc varchar(13) ); INSERT INTO emp VALUES ('7369','SMITH','CLERK','7902','1980-12-17','800.00',NULL,'20'), ('7499','ALLEN','SALESMAN','7698','1981-02-20','1600.00','300.00','30'), ('7521','WARD','SALESMAN','7698','1981-02-22','1250.00','500.00','30'), ('7566','JONES','MANAGER','7839','1981-04-02','2975.00',NULL,'20'), ('7654','MARTIN','SALESMAN','7698','1981-09-28','1250.00','1400.00','30'), ('7698','BLAKE','MANAGER','7839','1981-05-01','2850.00',NULL,'30'), ('7782','CLARK','MANAGER','7839','1981-06-09','2450.00',NULL,'10'), ('7788','SCOTT','ANALYST','7566','1982-12-09','3000.00',NULL,'20'), ('7839','KING','PRESIDENT',NULL,'1981-11-17','5000.00',NULL,'10'), ('7844','TURNER','SALESMAN','7698','1981-09-08','1500.00','0.00','30'), ('7876','ADAMS','CLERK','7788','1983-01-12','1100.00',NULL,'20'), ('7900','JAMES','CLERK','7698','1981-12-03','950.00',NULL,'30'), ('7902','FORD','ANALYST','7566','1981-12-03','3000.00',NULL,'20'), ('7934','MILLER','CLERK','7782','1982-01-23','1300.00',NULL,'10'); INSERT INTO dept VALUES ('10','ACCOUNTING','NEW YORK'), ('20','RESEARCH','DALLAS'), ('30','SALES','CHICAGO'), ('40','OPERATIONS','BOSTON'); # 启动 gdb root@1d1e15b4c637:/work/mysql# gdb GNU gdb (Debian 8.2.1-2+b3) 8.2.1 Type "apropos word" to search for commands related to "word". # attch 进 mysqld 进程 (gdb) attach 1400 Attaching to process 1400 [New LWP 1401] ... [New LWP 1430] [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". 0x00007eff45352819 in __GI___poll (fds=0x55582c637fe0, nfds=2, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:29 29 ../sysdeps/unix/sysv/linux/poll.c: No such file or directory.(gdb) source /work/mysql-breakpoints.txt Breakpoint 1 at 0x564cacb3121f: file /work/mysql-5.7.29/sql/sql_select.cc, line 107. Breakpoint 2 at 0x564caca9be4b: file /work/mysql-5.7.29/sql/sql_executor.cc, line 885. Breakpoint 3 at 0x564cacadca77: file /work/mysql-5.7.29/sql/sql_parse.cc, line 907. Breakpoint 4 at 0x564caca99b6b: file /work/mysql-5.7.29/sql/sql_executor.cc, line 106. Breakpoint 5 at 0x564cacac7045: file /work/mysql-5.7.29/sql/sql_optimizer.cc, line 5021. Breakpoint 6 at 0x564cacb007bb: file /work/mysql-5.7.29/sql/sql_planner.cc, line 1832. Breakpoint 7 at 0x564cacb0133b: file /work/mysql-5.7.29/sql/sql_planner.cc, line 2216.(gdb) info b Num Type Disp Enb Address What 1 breakpoint keep y 0x0000564cacb3121f in handle_query(THD*, LEX*, Query_result*, unsigned long long, unsigned long long) at /work/mysql-5.7.29/sql/sql_select.cc:107 2 breakpoint keep y 0x0000564caca9be4b in do_select(JOIN*) at /work/mysql-5.7.29/sql/sql_executor.cc:885 3 breakpoint keep y 0x0000564cacadca77 in do_command(THD*) at /work/mysql-5.7.29/sql/sql_parse.cc:907 4 breakpoint keep y 0x0000564caca99b6b in JOIN::exec() at /work/mysql-5.7.29/sql/sql_executor.cc:106 5 breakpoint keep y 0x0000564cacac7045 in JOIN::make_join_plan() at /work/mysql-5.7.29/sql/sql_optimizer.cc:5021 6 breakpoint keep y 0x0000564cacb007bb in Optimize_table_order::choose_table_order() at /work/mysql-5.7.29/sql/sql_planner.cc:1832 7 breakpoint keep y 0x0000564cacb0133b in Optimize_table_order::greedy_search(unsigned long long) at /work/mysql-5.7.29/sql/sql_planner.cc:2216(gdb) b handle_query Breakpoint 1 at 0x564cacb3121f: file /work/mysql-5.7.29/sql/sql_select.cc, line 107. (gdb) b do_select Breakpoint 2 at 0x564caca9be4b: file /work/mysql-5.7.29/sql/sql_executor.cc, line 885. (gdb) b do_command Breakpoint 3 at 0x564cacadca77: file /work/mysql-5.7.29/sql/sql_parse.cc, line 907. (gdb) b JOIN::exec Breakpoint 4 at 0x564caca99b6b: file /work/mysql-5.7.29/sql/sql_executor.cc, line 106. (gdb) b JOIN::make_join_plan Breakpoint 5 at 0x564cacac7045: file /work/mysql-5.7.29/sql/sql_optimizer.cc, line 5021. (gdb) b Optimize_table_order::choose_table_order Breakpoint 6 at 0x564cacb007bb: file /work/mysql-5.7.29/sql/sql_planner.cc, line 1832. (gdb) b Optimize_table_order::greedy_search Breakpoint 7 at 0x564cacb0133b: file /work/mysql-5.7.29/sql/sql_planner.cc, line 2216.(gdb) save breakpoints /work/mysql-breakpoints.txt Saved to file '/work/mysql-breakpoints.txt'.mysql> select a.empno, a.ename, b.dname, a.job, a.mgr, a.hiredate, a.sal, a.comm from emp a join dept b on b.deptno = a.deptno; # 此处查询挂起，等待gdb执行(gdb) c Continuing. Thread 28 "mysqld" hit Breakpoint 1, handle_query (thd=0x7fac3c000dd0, lex=0x7fac3c0030f0, result=0x7fac3c958248, added_options=0, removed_options=0) at /work/mysql-5.7.29/sql/sql_select.cc:107 107 DBUG_ENTER("handle_query"); (gdb) c Continuing. Thread 28 "mysqld" hit Breakpoint 5, JOIN::make_join_plan (this=0x7fac3c958fe0) at /work/mysql-5.7.29/sql/sql_optimizer.cc:5021 5021 DBUG_ENTER("JOIN::make_join_plan"); (gdb) c Continuing. Thread 28 "mysqld" hit Breakpoint 6, Optimize_table_order::choose_table_order (this=0x7facb0040f70) at /work/mysql-5.7.29/sql/sql_planner.cc:1832 1832 DBUG_ENTER("Optimize_table_order::choose_table_order"); (gdb) c Continuing. Thread 28 "mysqld" hit Breakpoint 7, Optimize_table_order::greedy_search (this=0x7facb0040f70, remaining_tables=3) at /work/mysql-5.7.29/sql/sql_planner.cc:2216 2216 uint idx= join->const_tables; // index into 'join->best_ref' # 打印调用栈 (gdb) bt #0 Optimize_table_order::greedy_search (this=0x7facb0040f70, remaining_tables=3) at /work/mysql-5.7.29/sql/sql_planner.cc:2216 #1 0x0000564cacb00c69 in Optimize_table_order::choose_table_order (this=0x7facb0040f70) at /work/mysql-5.7.29/sql/sql_planner.cc:1910 #2 0x0000564cacac7431 in JOIN::make_join_plan (this=0x7fac3c958fe0) at /work/mysql-5.7.29/sql/sql_optimizer.cc:5091 #3 0x0000564cacabbe29 in JOIN::optimize (this=0x7fac3c958fe0) at /work/mysql-5.7.29/sql/sql_optimizer.cc:375 #4 0x0000564cacb32d70 in st_select_lex::optimize (this=0x7fac3c005be0, thd=0x7fac3c000dd0) at /work/mysql-5.7.29/sql/sql_select.cc:1016 #5 0x0000564cacb314f6 in handle_query (thd=0x7fac3c000dd0, lex=0x7fac3c0030f0, result=0x7fac3c958248, added_options=0, removed_options=0) at /work/mysql-5.7.29/sql/sql_select.cc:171 #6 0x0000564cacae791b in execute_sqlcom_select (thd=0x7fac3c000dd0, all_tables=0x7fac3c956bf0) at /work/mysql-5.7.29/sql/sql_parse.cc:5155 #7 0x0000564cacae10f1 in mysql_execute_command (thd=0x7fac3c000dd0, first_level=true) at /work/mysql-5.7.29/sql/sql_parse.cc:2826 #8 0x0000564cacae8829 in mysql_parse (thd=0x7fac3c000dd0, parser_state=0x7facb0042650) at /work/mysql-5.7.29/sql/sql_parse.cc:5584 #9 0x0000564cacade006 in dispatch_command (thd=0x7fac3c000dd0, com_data=0x7facb0042df0, command=COM_QUERY) at /work/mysql-5.7.29/sql/sql_parse.cc:1491 #10 0x0000564cacadcf22 in do_command (thd=0x7fac3c000dd0) at /work/mysql-5.7.29/sql/sql_parse.cc:1032 #11 0x0000564cacc0c241 in handle_connection (arg=0x564caf501a00) at /work/mysql-5.7.29/sql/conn_handler/connection_handler_per_thread.cc:313 #12 0x0000564cad28e598 in pfs_spawn_thread (arg=0x564caf2c4d50) at /work/mysql-5.7.29/storage/perfschema/pfs.cc:2197 #13 0x00007facbd318fa3 in start_thread (arg=<optimized out>) at pthread_create.c:486 #14 0x00007facbcb584cf in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 # 查看源码 (gdb) list 2211 @return false if successful, true if error 2212*/ 2213 2214 bool Optimize_table_order::greedy_search(table_map remaining_tables) 2215 { 2216 uint idx= join->const_tables; // index into 'join->best_ref' 2217 uint best_idx; 2218 POSITION best_pos; 2219 JOIN_TAB *best_table; // the next plan node to be added to the curr QEP 2220 DBUG_ENTER("Optimize_table_order::greedy_search"); (gdb) c Continuing. Thread 28 "mysqld" hit Breakpoint 4, JOIN::exec (this=0x7fac3c958fe0) at /work/mysql-5.7.29/sql/sql_executor.cc:106 106 Opt_trace_context * const trace= &thd->opt_trace; (gdb) c Continuing. Thread 28 "mysqld" hit Breakpoint 2, do_select (join=0x7fac3c958fe0) at /work/mysql-5.7.29/sql/sql_executor.cc:885 885 int rc= 0; (gdb) c Continuing. Thread 28 "mysqld" hit Breakpoint 3, do_command (thd=0x7fac3c000dd0) at /work/mysql-5.7.29/sql/sql_parse.cc:907 907 (thd->get_protocol()->type() == Protocol::PROTOCOL_TEXT || (gdb) c Continuing.mysql> select a.empno, a.ename, b.dname, a.job, a.mgr, a.hiredate, a.sal, a.comm from emp a join dept b on b.deptno = a.deptno; +-------+--------+------------+-----------+------+------------+---------+---------+ | empno | ename | dname | job | mgr | hiredate | sal | comm | +-------+--------+------------+-----------+------+------------+---------+---------+ | 7369 | SMITH | RESEARCH | CLERK | 7902 | 1980-12-17 | 800.00 | NULL | | 7499 | ALLEN | SALES | SALESMAN | 7698 | 1981-02-20 | 1600.00 | 300.00 | | 7521 | WARD | SALES | SALESMAN | 7698 | 1981-02-22 | 1250.00 | 500.00 | | 7566 | JONES | RESEARCH | MANAGER | 7839 | 1981-04-02 | 2975.00 | NULL | | 7654 | MARTIN | SALES | SALESMAN | 7698 | 1981-09-28 | 1250.00 | 1400.00 | | 7698 | BLAKE | SALES | MANAGER | 7839 | 1981-05-01 | 2850.00 | NULL | | 7782 | CLARK | ACCOUNTING | MANAGER | 7839 | 1981-06-09 | 2450.00 | NULL | | 7788 | SCOTT | RESEARCH | ANALYST | 7566 | 1982-12-09 | 3000.00 | NULL | | 7839 | KING | ACCOUNTING | PRESIDENT | NULL | 1981-11-17 | 5000.00 | NULL | | 7844 | TURNER | SALES | SALESMAN | 7698 | 1981-09-08 | 1500.00 | 0.00 | | 7876 | ADAMS | RESEARCH | CLERK | 7788 | 1983-01-12 | 1100.00 | NULL | | 7900 | JAMES | SALES | CLERK | 7698 | 1981-12-03 | 950.00 | NULL | | 7902 | FORD | RESEARCH | ANALYST | 7566 | 1981-12-03 | 3000.00 | NULL | | 7934 | MILLER | ACCOUNTING | CLERK | 7782 | 1982-01-23 | 1300.00 | NULL | +-------+--------+------------+-----------+------+------------+---------+---------+ 14 rows in set (9 min 44.61 sec)Mysql优化器源码
https://blog.csdn.net/huoyuanshen/article/details/50420315
MySQL确定JOIN表顺序
https://zhuanlan.zhihu.com/p/102655586