在数据库运维工作中，经常需要对大表进行表结构变更，或者跑批。长事务执行进度，一直是我们关注的问题。MySQL8.0之前的版本并不支持查看长事务的执行进度。下边我们来一起学习。
MySQL5.7
对某大表添加组合索引：
alter table test_order add index idx_uid_pstatus_fix(user_id,perform_status,fixed);
查看sys.session视图信息：
MySQL> select * from sys.session where conn_id != connection_id() and current_statement like 'alter%' \G
*************************** 1. row ***************************
thd_id: 11790367
conn_id: 11790331
user: dba@10.9.6.98
db: xxx_performance
command: Query
state: alter table (read PK and internal sort)
time: 27
current_statement: alter table test_order ... (user_id,perform_status,fixed)
statement_latency: 27.65 s
progress: NULL
lock_latency: 991.00 us
rows_examined: 0
rows_sent: 0
rows_affected: 0
tmp_tables: 0
tmp_disk_tables: 0
full_scan: NO
last_statement: NULL
last_statement_latency: NULL
current_memory: 0 bytes
last_wait: NULL
last_wait_latency: NULL
source: NULL
trx_latency: NULL
trx_state: NULL
trx_autocommit: NULL
pid: 15520
program_name: NULL
1 row in set (0.15 sec)
MySQL5.7版本虽然也有statement_latency和progress字段，但是只有statement_latency字段显示数据（执行时间），而progress字段并不返回结果。
MySQL8.0 添加索引：
alter table test_order add index idx_uid_pstatus_fix(user_id,perform_status,fixed);
查看sys.session：
mysql> select * from sys.session where conn_id != connection_id() and current_statement like 'alter%' \G
*************************** 1. row ***************************
thd_id: 187
conn_id: 31
user: root@10.8.0.8
db: test
command: Query
state: alter table (read PK and internal sort)
time: 13
current_statement: alter table test_order add ind ... (user_id,perform_status,fixed)
statement_latency: 13.65 s
progress: 17.84
lock_latency: 459.00 us
rows_examined: 0
rows_sent: 0
rows_affected: 0
tmp_tables: 0
tmp_disk_tables: 0
full_scan: NO
last_statement: NULL
last_statement_latency: NULL
current_memory: 10.08 MiB
last_wait: wait/io/file/innodb/innodb_temp_file
last_wait_latency: 625.90 us
source: os0file.ic:473
trx_latency: 13.64 s
trx_state: ACTIVE
trx_autocommit: NO
pid: 15520
program_name: NULL
1 row in set (0.31 sec)
可以看到： statement_latency为13.65 s，表示此事务已执行13.65 s progress为17.84，表示执行进度为17.84%
