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本篇文章給大家分享的是有關 MySQL 中慢查詢記錄的原理是什么，丸趣 TV 小編覺得挺實用的，因此分享給大家學習，希望大家閱讀完這篇文章后可以有所收獲，話不多說，跟著丸趣 TV 小編一起來看看吧。
一、慢查詢中的時間
實際上慢查詢中的時間就是時鐘時間，是通過操作系統的命令獲得的時間，如下是 Linux 中獲取時間的方式
while (gettimeofday( t, NULL) != 0)
{}
newtime= (ulonglong)t.tv_sec * 1000000 + t.tv_usec; return newtime;實際上就是通過 OS 的 API gettimeofday 函數獲得的時間。
二、慢查詢記錄的依據
long_query_time：如果執行時間超過本參數設置記錄慢查詢。
log_queries_not_using_indexes：如果語句未使用索引記錄慢查詢。
log_slow_admin_statements：是否記錄管理語句。(如 ALTER TABLE,ANALYZE TABLE, CHECK TABLE, CREATE INDEX, DROP INDEX, OPTIMIZE TABLE, and REPAIR TABLE.)
本文主要討論 long_query_time 參數的含義。
三、long_query_time 參數的具體含義
如果我們將語句的執行時間定義為如下：
實際消耗時間 = 實際執行時間 + 鎖等待消耗時間那么 long_query_time 實際上界定的是實際執行時間，所以有些情況下雖然語句實際消耗的時間很長但是是因為鎖等待時間較長而引起的，那么實際上這種語句也不會記錄到慢查詢。
我們看一下 log_slow_applicable 函數的代碼片段：
res= cur_utime - thd- utime_after_lock; if (res thd- variables.long_query_time)
thd- server_status|= SERVER_QUERY_WAS_SLOW; else thd- server_status = ~SERVER_QUERY_WAS_SLOW;這里實際上清楚的說明了上面的觀點，是不是慢查詢就是通過這個函數進行的判斷的，非常重要。我可以清晰的看到如下公式：
res (實際執行時間) = cur_utime(實際消耗時間) – thd- utime_after_lock(鎖等待消耗時間)
實際上在慢查詢中記錄的正是
Query_time：實際執行時間
Lock_time：鎖等待消耗時間
但是是否是慢查詢其評判標準卻是實際執行時間及 Query_time – Lock_time
其中鎖等待消耗時間 (Lock_time) 我現在已經知道的包括：
MySQL 層 MDL LOCK 等待消耗的時間。(Waiting for table metadata lock)
MySQL 層 MyISAM 表鎖消耗的時間。(Waiting for table level lock)
InnoDB 層 行鎖消耗的時間。
四、MySQL 是如何記錄鎖時間
我們可以看到在公式中 utime_after_lock(鎖等待消耗時間 Lock_time)的記錄也就成了整個公式的關鍵，那么我們試著進行 debug。
1、MySQL 層 utime_after_lock 的記錄方式
不管是 MDL LOCK 等待消耗的時間還是 MyISAM 表鎖消耗的時間都是在 MySQL 層記錄的，實際上它只是記錄在函數 mysql_lock_tables 的末尾會調用的 THD::set_time_after_lock 進行的記錄時間而已如下：
void set_time_after_lock() { utime_after_lock= my_micro_time();
MYSQL_SET_STATEMENT_LOCK_TIME(m_statement_psi, (utime_after_lock - start_utime));
}那么這里可以解析為代碼運行到 mysql_lock_tables 函數的末尾之前的所有的時間都記錄到 utime_after_lock 時間中，實際上并不精確。但是實際上 MDL LOCK 的獲取和 MyISAM 表鎖的獲取都包含在里面。所以即便是 select 語句也會看到 Lock_time 并不為 0。下面是棧幀：
#0 THD::set_time_after_lock (this=0x7fff28012820) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_class.h:3414 #1 0x0000000001760d6d in mysql_lock_tables (thd=0x7fff28012820, tables=0x7fff28c16b58, count=1, flags=0) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/lock.cc:366 #2 0x000000000151dc1a in lock_tables (thd=0x7fff28012820, tables=0x7fff28c165b0, count=1, flags=0) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_base.cc:6700 #3 0x00000000017c4234 in Sql_cmd_delete::mysql_delete (this=0x7fff28c16b50, thd=0x7fff28012820, limit=18446744073709551615) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_delete.cc:136 #4 0x00000000017c84ba in Sql_cmd_delete::execute (this=0x7fff28c16b50, thd=0x7fff28012820) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_delete.cc:1389 #5 0x00000000015a7814 in mysql_execute_command (thd=0x7fff28012820, first_level=true) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_parse.cc:3729 #6 0x00000000015adcd6 in mysql_parse (thd=0x7fff28012820, parser_state=0x7ffff035b600) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_parse.cc:5836 #7 0x00000000015a1b95 in dispatch_command (thd=0x7fff28012820, com_data=0x7ffff035bd70, command=COM_QUERY) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_parse.cc:1447 #8 0x00000000015a09c6 in do_command (thd=0x7fff28012820) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_parse.cc:10102、InnoDB 層的行鎖的 utime_after_lock 記錄方式
InnoDB 引擎層調用通過 thd_set_lock_wait_time 調用 thd_storage_lock_wait 函數完成的棧幀如下：
#0 thd_storage_lock_wait (thd=0x7fff2c000bc0, value=9503561) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_class.cc:798 #1 0x00000000019a4b2a in thd_set_lock_wait_time (thd=0x7fff2c000bc0, value=9503561) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/handler/ha_innodb.cc:1784 #2 0x0000000001a4b50f in lock_wait_suspend_thread (thr=0x7fff2c088200) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/lock/lock0wait.cc:363 #3 0x0000000001b0ec9b in row_mysql_handle_errors (new_err=0x7ffff0317d54, trx=0x7ffff2f2e5d0, thr=0x7fff2c088200, savept=0x0) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/row/row0mysql.cc:772 #4 0x0000000001b4fe61 in row_search_mvcc (buf=0x7fff2c087640 \377 , mode=PAGE_CUR_G, prebuilt=0x7fff2c087ac0, match_mode=0, direction=0) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/row/row0sel.cc:5940 #5 0x00000000019b3051 in ha_innobase::index_read (this=0x7fff2c087100, buf=0x7fff2c087640 \377 , key_ptr=0x0, key_len=0, find_flag=HA_READ_AFTER_KEY) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/handler/ha_innodb.cc:9104 #6 0x00000000019b4374 in ha_innobase::index_first (this=0x7fff2c087100, buf=0x7fff2c087640 \377) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/handler/ha_innodb.cc:9551 #7 0x00000000019b462c in ha_innobase::rnd_next (this=0x7fff2c087100, buf=0x7fff2c087640 \377) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/handler/ha_innodb.cc:9656 #8 0x0000000000f66f1b in handler::ha_rnd_next (this=0x7fff2c087100, buf=0x7fff2c087640 \377) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/handler.cc:3099 #9 0x00000000014c61b6 in rr_sequential (info=0x7ffff03189e0) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/records.cc:520 #10 0x00000000017c56c3 in Sql_cmd_delete::mysql_delete (this=0x7fff2c006ae8, thd=0x7fff2c000bc0, limit=1) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_delete.cc:454 #11 0x00000000017c84ba in Sql_cmd_delete::execute (this=0x7fff2c006ae8, thd=0x7fff2c000bc0) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_delete.cc:1389函數本身還是很簡單自己看看就知道了就是相加而已如下：
void thd_storage_lock_wait(THD *thd, long long value) { thd- utime_after_lock+= value;}五、Percona 中的 log_slow_verbosity 參數
這是 Percona 的解釋：
Specifies how much information to include in your slow log. The value is a comma-delimited string, and can contain any combination of the following values:
microtime: Log queries with microsecond precision (mandatory).
query_plan: Log information about the query’s execution plan (optional).
innodb: Log InnoDB statistics (optional).
minimal: Equivalent to enabling just microtime.
standard: Equivalent to enabling microtime,innodb.
full: Equivalent to all other values OR’ed together.
總之在 Percona 中可以修改這個參數獲得更加詳細的信息大概的格式如下：
# Time: 2018-05-30T09:30:12.039775Z # User@Host: root[root] @ localhost [] Id: 10 # Schema: test Last_errno: 1317 Killed: 0 # Query_time: 19.254508 Lock_time: 0.001043 Rows_sent: 0 Rows_examined: 0 Rows_affected: 0 # Bytes_sent: 44 Tmp_tables: 0 Tmp_disk_tables: 0 Tmp_table_sizes: 0 # InnoDB_trx_id: 0 # QC_Hit: No Full_scan: No Full_join: No Tmp_table: No Tmp_table_on_disk: No # Filesort: No Filesort_on_disk: No Merge_passes: 0 # InnoDB_IO_r_ops: 0 InnoDB_IO_r_bytes: 0 InnoDB_IO_r_wait: 0.000000 # InnoDB_rec_lock_wait: 0.000000 InnoDB_queue_wait: 0.000000 # InnoDB_pages_distinct: 0 SET timestamp=1527672612;
select count(*) from z1 limit 1;六、輸出的詳細解釋
本節將會進行詳細的解釋，全部的慢查詢的輸出都來自于函數 File_query_log::write_slow，有興趣的同學可以自己看看，我這里也會給出輸出的位置和含義，其中含義部分可能給出的是源碼中的注釋。
1、第一部分時間
# Time: 2018-05-30T09:30:12.039775Z對應的代碼：
my_snprintf(buff, sizeof buff, # Time: %s\n , my_timestamp);其中 my_timestamp 取值來自于
thd- current_utime();實際上就是：
while (gettimeofday( t, NULL) != 0)
{}
newtime= (ulonglong)t.tv_sec * 1000000 + t.tv_usec; return newtime;可以看到實際就是調用 gettimeofday 系統調用得到的系統當前時間。
注意：
對于 5.6 來講還有一句判斷
if (current_time != last_time)如果兩次打印的時間秒鐘一致則不會輸出時間，只有通過后面介紹的
SET timestamp=1527753496;來判斷時間，5.7.14 沒有看到這樣的代碼。
2、第二部分用戶信息
# User@Host: root[root] @ localhost [] Id: 10對應的代碼：
buff_len= my_snprintf(buff, 32, %5u , thd- thread_id()); if (my_b_printf( log_file, # User@Host: %s Id: %s\n , user_host, buff)
== (uint) -1) goto err;
}user_host 是一串字符串，參考代碼：
size_t user_host_len= (strxnmov(user_host_buff, MAX_USER_HOST_SIZE,
sctx- priv_user().str
? sctx- priv_user().str : , [ , sctx_user.length ? sctx_user.str :
(thd- slave_thread ? SQL_SLAVE : ), ] @ ,
sctx_host.length ? sctx_host.str : , [ ,
sctx_ip.length ? sctx_ip.str : , ] ,
NullS) - user_host_buff);解釋如下：
root: m_priv_user – The user privilege we are using. May be for anonymous user。
[root]: m_user – user of the client, set to NULL until the user has been read from the connection。
localhost: m_host – host of the client。
[]:client IP m_ip – client IP。
Id: 10 thd- thread_id()實際上就是 show processlist 出來的 id。
3、第三部分 schema 等信息
# Schema: test Last_errno: 1317 Killed: 0對應的代碼：
# Schema: %s Last_errno: %u Killed: %u\n (thd- db().str ? thd- db().str : ),
thd- last_errno, (uint) thd- killed,
Schema:
m_db Name of the current (default) database.If there is the current (default) database, db contains its name. If there is no current (default) database, db is NULL and db_length is 0. In other words, db , db_length must either be NULL, or contain a valid database name.
Last_errno:
Variable last_errno contains the last error/warning acquired during query execution.
Killed: 這里代表的是終止的錯誤碼。源碼中如下：
enum killed_state
{
NOT_KILLED=0,
KILL_BAD_DATA=1,
KILL_CONNECTION=ER_SERVER_SHUTDOWN,
KILL_QUERY=ER_QUERY_INTERRUPTED,
KILL_TIMEOUT=ER_QUERY_TIMEOUT,
KILLED_NO_VALUE /* means neither of the states */
};
在錯誤碼中代表如下：
{ER_SERVER_SHUTDOWN , 1053, Server shutdown in progress},
{ER_QUERY_INTERRUPTED , 1317, Query execution was interrupted},
{ER_QUERY_TIMEOUT , 1886, Query execution was interrupted, max_statement_time exceeded},
4、第四部分執行信息
這部分可能是大家最關心的部分，很多信息也是默認輸出都會輸出的。
# Query_time: 19.254508 Lock_time: 0.001043 Rows_sent: 0 Rows_examined: 0 Rows_affected: 0 # Bytes_sent: 44 Tmp_tables: 0 Tmp_disk_tables: 0 Tmp_table_sizes: 0 # InnoDB_trx_id: 0對應代碼：
my_b_printf( log_file, # Schema: %s Last_errno: %u Killed: %u\n # Query_time: %s Lock_time: %s Rows_sent: %llu Rows_examined: %llu Rows_affected: %llu\n # Bytes_sent: %lu ,
(thd- db().str ? thd- db().str : ),
thd- last_errno, (uint) thd- killed,
query_time_buff, lock_time_buff,
(ulonglong) thd- get_sent_row_count(),
(ulonglong) thd- get_examined_row_count(),
(thd- get_row_count_func() 0)
? (ulonglong) thd- get_row_count_func() : 0,
(ulong) (thd- status_var.bytes_sent - thd- bytes_sent_old)
my_b_printf( log_file, Tmp_tables: %lu Tmp_disk_tables: %lu Tmp_table_sizes: %llu ,
thd- tmp_tables_used, thd- tmp_tables_disk_used,
thd- tmp_tables_size)
snprintf(buf, 20, %llX , thd- innodb_trx_id); 及 thd- innodb_trx_idQuery_time：語句執行的時間及實際消耗時間。
Lock_time：包含 MDL lock 和 InnoDB row lock 和 MyISAM 表鎖消耗時間的總和及鎖等待消耗時間。前面已經進行了描述(實際上也并不全是鎖等待的時間只是鎖等待包含在其中)。
我們來看看 Query_time 和 Lock_time 的源碼來源，它們來自于 Query_logger::slow_log_write 函數如下： query_utime= (current_utime thd- start_utime) ? (current_utime - thd- start_utime) : 0; lock_utime= (thd- utime_after_lock thd- start_utime) ? (thd- utime_after_lock - thd- start_utime) : 0; 下面是數據 current_utime 的來源，current_utime=thd- current_utime();實際上就是：獲取當前時間而已 對于 thd- utime_after_lock 的獲取我已經在前文進行了描述，不再解釋。while (gettimeofday( t, NULL) != 0) {} newtime= (ulonglong)t.tv_sec * 1000000 + t.tv_usec; return newtime;
Rows_sent：發送給 mysql 客戶端的行數，下面是源碼中的解釋
Number of rows we actually sent to the client
Rows_examined：InnoDB 引擎層掃描的行數, 下面是源碼中的解釋。(備注棧幀 1)
Number of rows read and/or evaluated for a statement. Used for slow log reporting.
An examined row is defined as a row that is read and/or evaluated
according to a statement condition, including increate_sort_index(). Rows may be counted more than once, e.g., a statement including ORDER BY could possibly evaluate the row in filesort() before reading it for e.g. update.
Rows_affected：涉及到修改的話 (比如 DML 語句) 這是受影響的行數。
for DML statements: to the number of affected rows;
for DDL statements: to 0.
Bytes_sent：發送給客戶端的實際數據的字節數，它來自于
(ulong) (thd- status_var.bytes_sent – thd- bytes_sent_old)
Tmp_tables：臨時表的個數。
Tmp_disk_tables：磁盤臨時表的個數。
Tmp_table_sizes：臨時表的大小。
以上三個指標來自于：
thd- tmp_tables_used
thd- tmp_tables_disk_used
thd- tmp_tables_size這三個指標增加的位置對應在 free_tmp_table 函數中如下：
thd- tmp_tables_used++; if (entry- file)
{ thd- tmp_tables_size += entry- file- stats.data_file_length; if (entry- file- ht- db_type != DB_TYPE_HEAP)
thd- tmp_tables_disk_used++;
}InnoDB_trx_id：事物 ID，也就是 trx- id，/*! transaction id */
5、第五部分優化器相關信息
# QC_Hit: No Full_scan: No Full_join: No Tmp_table: No Tmp_table_on_disk: No # Filesort: No Filesort_on_disk: No Merge_passes: 0這一行來自于如下代碼：
my_b_printf( log_file, # QC_Hit: %s Full_scan: %s Full_join: %s Tmp_table: %s Tmp_table_on_disk: %s\n \ # Filesort: %s Filesort_on_disk: %s Merge_passes: %lu\n ,
((thd- query_plan_flags QPLAN_QC) ? Yes : No ),
((thd- query_plan_flags QPLAN_FULL_SCAN) ? Yes : No ),
((thd- query_plan_flags QPLAN_FULL_JOIN) ? Yes : No ),
((thd- query_plan_flags QPLAN_TMP_TABLE) ? Yes : No ),
((thd- query_plan_flags QPLAN_TMP_DISK) ? Yes : No ),
((thd- query_plan_flags QPLAN_FILESORT) ? Yes : No ),
((thd- query_plan_flags QPLAN_FILESORT_DISK) ? Yes : No ),這里注意一個處理的技巧，這里 query_plan_flags 中每一位都代表一個含義，這樣存儲既能存儲足夠多的信息同時存儲空間也很小，是 C /C++ 中常用的方式。
QC_Hit: No：是否 query cache 命中。
Full_scan: 此處相當于 Select_scan 的含義，是否進行了全掃描包括 using index。
Full_join: 此處相當于 Select_full_join 的含義，是否被驅動表使用到了索引，如果沒有使用到索引則為 YES。
考慮如下的執行計劃
mysql desc select *,sleep(1) from testuin a,testuin1 b where a.id1=b.id1;
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+----------------------------------------------------+ | id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+----------------------------------------------------+
| 1 | SIMPLE | a | NULL | ALL | NULL | NULL | NULL | NULL | 5 | 100.00 | NULL | | 1 | SIMPLE | b | NULL | ALL | NULL | NULL | NULL | NULL | 5 | 20.00 | Using where; Using join buffer (Block Nested Loop) |
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+----------------------------------------------------+
2 rows in set, 1 warning (0.00 sec)如此輸出如下：
# QC_Hit: No Full_scan: Yes Full_join: YesTmp_table: 是否使用了臨時表，在函數 create_tmp_table 中設置。
Tmp_table_on_disk: 是否使用了磁盤臨時表，如果時候 innodb 引擎則在 create_innodb_tmp_table 函數中設置。
Filesort: 是否進行了排序，在函數 filesort 中設置。
Filesort_on_disk: 是否使用了磁盤排序，同樣在函數 filesort 中設置，但是設置之前會進行是否需要磁盤排序文件的判斷。
Merge_passes: 進行多路歸并排序，歸并的次數。
Variable query_plan_fsort_passes collects information about file sort passes
acquired during query execution.
6、第六部分 InnoDB 相關信息
# InnoDB_IO_r_ops: 0 InnoDB_IO_r_bytes: 0 InnoDB_IO_r_wait: 0.000000 # InnoDB_rec_lock_wait: 0.000000 InnoDB_queue_wait: 0.000000 # InnoDB_pages_distinct: 0這一行來自于如下代碼：
char buf[3][20];
snprintf(buf[0], 20, %.6f , thd- innodb_io_reads_wait_timer / 1000000.0);
snprintf(buf[1], 20, %.6f , thd- innodb_lock_que_wait_timer / 1000000.0);
snprintf(buf[2], 20, %.6f , thd- innodb_innodb_que_wait_timer / 1000000.0); if (my_b_printf( log_file, # InnoDB_IO_r_ops: %lu InnoDB_IO_r_bytes: %llu InnoDB_IO_r_wait: %s\n # InnoDB_rec_lock_wait: %s InnoDB_queue_wait: %s\n # InnoDB_pages_distinct: %lu\n ,
thd- innodb_io_reads, thd- innodb_io_read,
buf[0], buf[1], buf[2], thd- innodb_page_access)
== (uint) -1)InnoDB_IO_r_ops: 物理 IO 讀取次數。
InnoDB_IO_r_bytes: 物理 IO 讀取的總字節數。
InnoDB_IO_r_wait: 物理 IO 讀取等待的時間。innodb 使用 BUF_IO_READ 標記為物理 io 讀取繁忙，參考函數 buf_wait_for_read。
InnoDB_rec_lock_wait: 等待行鎖消耗的時間。在函數 que_thr_end_lock_wait 中設置。
InnoDB_queue_wait: 等待進入 innodb 引擎消耗的時間，在函數 srv_conc_enter_innodb_with_atomics 中設置。(參考 http://blog.itpub.net/7728585/viewspace-2140446/)
InnoDB_pages_distinct: innodb 訪問的頁數，包含物理和邏輯 IO，在函數 buf_page_get_gen 的末尾通過_increment_page_get_statistics 函數設置。
7、第七部分 set timestamp
SET timestamp=1527753496;這一句來自源碼，注意源碼注釋解釋就是獲取的服務器的當前的時間(current_utime)。
/*
This info used to show up randomly, depending on whether the query
checked the query start time or not. now we always write current
timestamp to the slow log
*/ end= my_stpcpy(end, ,timestamp=
end= int10_to_str((long) (current_utime / 1000000), end, 10); if (end != buff)
{
*end++=
*end= \n if (my_b_write( log_file, (uchar*) SET , 4) ||
my_b_write(log_file, (uchar*) buff + 1, (uint) (end-buff))) goto err;
}
七、總結
本文通過查詢源碼解釋了一些關于 MySQL 慢查詢的相關的知識，主要解釋了慢查詢是基于什么標準進行記錄的，同時輸出中各個指標的含義，當然這僅僅是我自己得出的結果，如果有不同意見可以一起討論。
備注棧幀 1：
本棧幀主要跟蹤 Rows_examined 的變化及 join- examined_rows++; 的變化
(gdb) info b
Num Type Disp Enb Address What
1 breakpoint keep y 0x0000000000ebd5f3 in main(int, char**) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/main.cc:25
breakpoint already hit 1 time
4 breakpoint keep y 0x000000000155b94f in do_select(JOIN*) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_executor.cc:872
breakpoint already hit 5 times 5 breakpoint keep y 0x000000000155ca39 in evaluate_join_record(JOIN*, QEP_TAB*) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_executor.cc:1473
breakpoint already hit 20 times 6 breakpoint keep y 0x00000000019b4313 in ha_innobase::index_first(uchar*)
at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/handler/ha_innodb.cc:9547
breakpoint already hit 4 times 7 breakpoint keep y 0x00000000019b45cd in ha_innobase::rnd_next(uchar*)
at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/handler/ha_innodb.cc:9651
8 breakpoint keep y 0x00000000019b2ba6 in ha_innobase::index_read(uchar*, uchar const*, uint, ha_rkey_function)
at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/handler/ha_innodb.cc:9004
breakpoint already hit 3 times 9 breakpoint keep y 0x00000000019b4233 in ha_innobase::index_next(uchar*)
at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/handler/ha_innodb.cc:9501
breakpoint already hit 5 times #0 ha_innobase::index_next (this=0x7fff2cbc6b40, buf=0x7fff2cbc7080 \375\n) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/handler/ha_innodb.cc:9501 #1 0x0000000000f680d8 in handler::ha_index_next (this=0x7fff2cbc6b40, buf=0x7fff2cbc7080 \375\n) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/handler.cc:3269 #2 0x000000000155fa02 in join_read_next (info=0x7fff2c007750) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_executor.cc:2660 #3 0x000000000155c397 in sub_select (join=0x7fff2c007020, qep_tab=0x7fff2c007700, end_of_records=false) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_executor.cc:1274 #4 0x000000000155bd06 in do_select (join=0x7fff2c007020) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_executor.cc:944 #5 0x0000000001559bdc in JOIN::exec (this=0x7fff2c007020) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_executor.cc:199 #6 0x00000000015f9ea6 in handle_query (thd=0x7fff2c000b70, lex=0x7fff2c003150, result=0x7fff2c006cd0, added_options=0, removed_options=0) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_select.cc:184 #7 0x00000000015acd05 in execute_sqlcom_select (thd=0x7fff2c000b70, all_tables=0x7fff2c006688) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_parse.cc:5391 #8 0x00000000015a5320 in mysql_execute_command (thd=0x7fff2c000b70, first_level=true) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_parse.cc:2889 #9 0x00000000015adcd6 in mysql_parse (thd=0x7fff2c000b70, parser_state=0x7ffff035b600) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_parse.cc:5836 #10 0x00000000015a1b95 in dispatch_command (thd=0x7fff2c000b70, com_data=0x7ffff035bd70, command=COM_QUERY) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_parse.cc:1447 #11 0x00000000015a09c6 in do_command (thd=0x7fff2c000b70) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_parse.cc:1010 #12 0x00000000016e29d0 in handle_connection (arg=0x3859ae0) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/conn_handler/connection_handler_per_thread.cc:312 #13 0x0000000001d7bfdc in pfs_spawn_thread (arg=0x38607b0) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/perfschema/pfs.cc:2188 #14 0x0000003f74807aa1 in start_thread () from /lib64/libpthread.so.0 #15 0x0000003f740e8bcd in clone () from /lib64/libc.so.6以上就是 MySQL 中慢查詢記錄的原理是什么，丸趣 TV 小編相信有部分知識點可能是我們日常工作會見到或用到的。希望你能通過這篇文章學到更多知識。更多詳情敬請關注丸趣 TV 行業資訊頻道。
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