事務(wù)結(jié)構(gòu) struct trx_t

寫(xiě)在前面

InnoDB是MySQL的一個(gè)存儲(chǔ)引擎，支持事務(wù)，支持非堵塞的一致性讀，物理存儲(chǔ)結(jié)構(gòu)是Page，每個(gè)事務(wù)都有回滾日志，重做日志，事務(wù)還會(huì)有死鎖檢測(cè)，各種各樣不同的鎖等等等等

翻看innodb的源碼，發(fā)現(xiàn)數(shù)下來(lái)開(kāi)啟一個(gè)事務(wù)的時(shí)候，InnoDB需要處理63個(gè)變量，變量類(lèi)型紛繁復(fù)雜，結(jié)構(gòu)體，自定義的數(shù)據(jù)類(lèi)型等等。

這次整理，我翻看了不少同行們寫(xiě)的博客，包括InnoDB官方博客，有一個(gè)心得是不同人的翻譯不一樣，盡管是官方寫(xiě)的博客，也會(huì)因?yàn)橐恍┢鶈?wèn)題，減掉了一些細(xì)節(jié)的介紹。這次的整理，我特意保留了原來(lái)的英文備注，然后加上自己的理解進(jìn)去。

MySQL的源碼文件很多，InnoDB也不少，不過(guò)我覺(jué)得事務(wù)的結(jié)構(gòu)體代碼還是要理解透的，透了才能理解透事務(wù)的實(shí)現(xiàn)細(xì)節(jié)，更加深入認(rèn)識(shí)數(shù)據(jù)庫(kù)系統(tǒng)為了保證數(shù)據(jù)的一致性，做了多少事情....

文件地址

文件地址

storage/innobase/include/trx0trx.h

變量1 magic_n

變量類(lèi)型 ulint #define ulint unsigned long

變量2 mutex

變量類(lèi)型 ib_mutex_t

mutex的代碼備注

Mutex protecting the fields state and lock (except some fields of lock, which are protected by lock_sys->mutex) Mutex保護(hù)字段的狀態(tài)和鎖定（除了某些鎖定字段，由lock_sys-> mutex保護(hù)）

ib_mutex_t對(duì)應(yīng)的結(jié)構(gòu)體

/** InnoDB mutex */ struct ib_mutex_t {os_event_t event; /*!< Used by sync0arr.cc for the wait queue */volatile lock_word_t lock_word; /*!< lock_word is the targetof the atomic test-and-set instruction whenatomic operations are enabled. */

這里面又有另外一個(gè)結(jié)構(gòu)體 os_event_t

/** An asynchronous signal sent between threads */ struct os_event { #ifdef __WIN__HANDLE handle; /*!< kernel event object, slow,used on older Windows */ #endifos_fast_mutex_t os_mutex; /*!< this mutex protects the nextfields */ibool is_set; /*!< this is TRUE when the event isin the signaled state, i.e., a threaddoes not stop if it tries to wait forthis event */ib_int64_t signal_count; /*!< this is incremented each timethe event becomes signaled */os_cond_t cond_var; /*!< condition variable is used inwaiting for the event */UT_LIST_NODE_T(os_event_t) os_event_list;/*!< list of all created events */ };

變量3 state

變量類(lèi)型 trx_state_t 變量備注

事務(wù)狀態(tài)TRX_STATE_NOT_STARTED TRX_STATE_ACTIVE TRX_STATE_PREPARED TRX_STATE_COMMITTED_IN_MEMORY (alias below COMMITTED)

結(jié)構(gòu)體trx_state_t的源碼

/** Transaction states (trx_t::state) */ enum trx_state_t {TRX_STATE_NOT_STARTED,TRX_STATE_ACTIVE,TRX_STATE_PREPARED, /* Support for 2PC/XA */TRX_STATE_COMMITTED_IN_MEMORY };

變量4 lock

變量類(lèi)型 trx_lock_t

變量備注

Information about the transaction locks and state. Protected by trx->mutex or lock_sys->mutex or both 事務(wù)鎖和狀態(tài)有關(guān)的信息。 受trx-> mutex或lock_sys-> mutex或兩者保護(hù)

trx_lock_t的結(jié)構(gòu)體定義

struct trx_lock_t {ulint n_active_thrs; /*!< number of active query threads */trx_que_t que_state; /*!< valid when trx->state== TRX_STATE_ACTIVE: TRX_QUE_RUNNING,TRX_QUE_LOCK_WAIT, ... */lock_t* wait_lock; /*!< if trx execution state isTRX_QUE_LOCK_WAIT, this points tothe lock request, otherwise this isNULL; set to non-NULL when holdingboth trx->mutex and lock_sys->mutex;set to NULL when holdinglock_sys->mutex; readers shouldhold lock_sys->mutex, except whenthey are holding trx->mutex andwait_lock==NULL */ib_uint64_t deadlock_mark; /*!< A mark field that is initializedto and checked against lock_mark_counterby lock_deadlock_recursive(). */ibool was_chosen_as_deadlock_victim;/*!< when the transaction decides towait for a lock, it sets this to FALSE;if another transaction chooses thistransaction as a victim in deadlockresolution, it sets this to TRUE.Protected by trx->mutex. */time_t wait_started; /*!< lock wait started at this time,protected only by lock_sys->mutex */que_thr_t* wait_thr; /*!< query thread belonging to thistrx that is in QUE_THR_LOCK_WAITstate. For threads suspended in alock wait, this is protected bylock_sys->mutex. Otherwise, this mayonly be modified by the thread that isserving the running transaction. */mem_heap_t* lock_heap; /*!< memory heap for trx_locks;protected by lock_sys->mutex */UT_LIST_BASE_NODE_T(lock_t)trx_locks; /*!< locks requestedby the transaction;insertions are protected by trx->mutexand lock_sys->mutex; removals areprotected by lock_sys->mutex */ib_vector_t* table_locks; /*!< All table locks requested by thistransaction, including AUTOINC locks */ibool cancel; /*!< TRUE if the transaction is beingrolled back either via deadlockdetection or due to lock timeout. Thecaller has to acquire the trx_t::mutexin order to cancel the locks. Inlock_trx_table_locks_remove() wecheck for this cancel of a transaction'slocks and avoid reacquiring the trxmutex to prevent recursive deadlocks.Protected by both the lock sys mutexand the trx_t::mutex. */ };

變量5 is_recovered

變量類(lèi)型 ulint 變量備注

0=normal transaction, 1=recovered, must be rolled back, protected by trx_sys->mutex when trx->in_rw_trx_list holds 0 =正常事務(wù)，1 =恢復(fù)，必須回滾，當(dāng)trx-> in_rw_trx_list保持時(shí)由trx_sys-> mutex保護(hù)

變量6 op_info

變量類(lèi)型 const char*

變量7 isolation_level

變量類(lèi)型 ulint 變量備注 READ UNCOMMITTED,READ COMMITTED,REPEATABLE READ,SERIALIZABLE

變量8 is_registered:1

變量類(lèi)型 unsigned 變量備注

MySQL has a transaction coordinator to coordinate two phase commit between multiple storage engines and the binary log. When an engine participates in a transaction, it's responsible for registering itself using the trans_register_ha() API. This flag is set to 1 after the transaction has been registered with the coordinator using the XA API, and is set to 0 after commit or rollback

MySQL有一個(gè)事務(wù)協(xié)調(diào)器來(lái)協(xié)調(diào)多個(gè)存儲(chǔ)引擎和二進(jìn)制日志之間的兩階段提交,它負(fù)責(zé)使用trans_register_ha（）API注冊(cè)自己.

在事務(wù)已使用XA API向協(xié)調(diào)器注冊(cè)后，此標(biāo)志設(shè)置為1，并在提交或回滾后設(shè)置為0

變量9 check_unique_secondary

變量類(lèi)型 ulint

變量備注

通常為T(mén)RUE，但是如果用戶(hù)想要通過(guò)抑制對(duì)二級(jí)索引的唯一鍵檢查來(lái)加快插入，當(dāng)我們決定是否可以為它們使用插入緩沖區(qū)時(shí)，我們?cè)O(shè)置這個(gè)FALSE

變量10 support_xa

變量類(lèi)型 ulint

變量備注 normally we do the XA two-phase commit steps, but by setting this to FALSE, one can save CPU time and about 150 bytes in the undo log size as then we skip XA steps

通常我們做XA兩階段提交步驟,但通過(guò)設(shè)置為FALSE,可以節(jié)省CPU時(shí)間和大約150字節(jié)的undo日志大小，然后我們跳過(guò)XA步驟

變量11 flush_log_later

變量類(lèi)型 ulint

變量備注

In 2PC, we hold the prepare_commit mutex across both phases. In that case, we defer flush of the logs to disk until after we release the mutex

在兩階段提交，我們持有兩個(gè)階段的prepare_commit互斥體。 在這種情況下，我們推遲刷新日志到磁盤(pán)，直到我們釋放互斥體。

變量12 must_flush_log_later

變量類(lèi)型 ulint

變量備注

this flag is set to TRUE in trx_commit() if flush_log_later was TRUE, and there were modifications by the transaction; in that case we must flush the log in trx_commit_complete_for_mysql()

此標(biāo)志在trx_commit（）中設(shè)置為T(mén)RUE，如果flush_log_later為T(mén)RUE，并且事務(wù)進(jìn)行了修改； 在這種情況下，我們必須通過(guò)trx_commit_complete_for_mysql（）刷新日志

變量13 duplicates

變量類(lèi)型 ulint

變量備注 TRX_DUP_IGNORE | TRX_DUP_REPLACE

變量14 has_search_latch

變量類(lèi)型 ulint

變量備注

TRUE if this trx has latched the search system latch in S-mode 如果此trx已在S模式下鎖定搜索系統(tǒng)鎖存器，則為T(mén)RUE

變量15 search_latch_timeout

變量類(lèi)型 ulint

變量備注

If we notice that someone is waiting for our S-lock on the search latch to be released, we wait in?row0sel.cc?for BTR_SEA_TIMEOUT new searches until we try to keep the search latch again over calls from MySQL; this is intended to reduce contention on the search latch

如果我們注意到有事務(wù)在等待我們的S鎖鎖定被釋放，我們?cè)趓ow0sel.cc中等待BTR_SEA_TIMEOUT新的搜索，直到我們嘗試保持搜索鎖定再次超過(guò)來(lái)自MySQL的調(diào)用; 這旨在減少對(duì)搜索鎖存器的爭(zhēng)用

變量16 dict_operation

變量類(lèi)型 trx_dict_op_t

變量備注

主要是三種狀態(tài) 沒(méi)有修改表結(jié)構(gòu)=0 改表=1 修改索引=2

/** Type of data dictionary operation */ enum trx_dict_op_t {/** The transaction is not modifying the data dictionary. */TRX_DICT_OP_NONE = 0,/** The transaction is creating a table or an index, ordropping a table. The table must be dropped in crashrecovery. This and TRX_DICT_OP_NONE are the only possibleoperation modes in crash recovery. */TRX_DICT_OP_TABLE = 1,/** The transaction is creating or dropping an index in anexisting table. In crash recovery, the data dictionarymust be locked, but the table must not be dropped. */TRX_DICT_OP_INDEX = 2 };

變量17 declared_to_be_inside_innodb

變量 ulint

備注

this is TRUE if we have declared this transaction in srv_conc_enter_innodb to be inside the InnoDB engine 如果我們已經(jīng)在srv_conc_enter_innodb中聲明這個(gè)事務(wù)在InnoDB引擎中，那么這是TRUE

變量18 n_tickets_to_enter_innodb

變量類(lèi)型 ulint

變量備注

< this can be > 0 only when declared_to_... is TRUE; when we come to srv_conc_innodb_enter, if the value here is > 0, we decrement this by 1

<這可以> 0只有當(dāng)declared_to_be_inside_innodb _…為T(mén)RUE 當(dāng)我們來(lái)到srv_conc_innodb_enter，如果這里的值> 0，我們將其減1

變量19 dict_operation_lock_mode

變量類(lèi)型 ulint

變量備注

0, RW_S_LATCH, or RW_X_LATCH: the latch mode trx currently holds on dict_operation_lock. Protected by dict_operation_lock 0，RW_S_LATCH或RW_X_LATCH：鎖存模式trx當(dāng)前持有dict_operation_lock。 受dict_operation_lock保護(hù)

變量20 no

變量類(lèi)型 trx_id_t

storage/innobase/include/univ.i typedef ib_uint64_t ib_id_t;storage/innobase/include/trx0types.h /** Transaction identifier (DB_TRX_ID, DATA_TRX_ID) */ typedef ib_id_t trx_id_t;

變量備注

transaction serialization number: max trx id shortly before the transaction is moved to COMMITTED_IN_MEMORY state. Protected by trx_sys_t::mutex when trx->in_rw_trx_list. Initially set to TRX_ID_MAX

事務(wù)序列號(hào)：事務(wù)被移動(dòng)到COMMITTED_IN_MEMORY狀態(tài)之前不久的max trx id。 當(dāng)trx-> in_rw_trx_list時(shí)，由trx_sys_t :: mutex保護(hù)。 最初設(shè)置為T(mén)RX_ID_MAX

變量21 start_time

變量類(lèi)型 time_t

變量備注 time the trx state last time became TRX_STATE_ACTIVE

trx狀態(tài)變?yōu)門(mén)RX_STATE_ACTIVE的上一次時(shí)間（開(kāi)始時(shí)間）

變量22 id

變量類(lèi)型 trx_id_t

變量備注 transaction id 事務(wù)id

變量23 XID

變量類(lèi)型 XID

sql/handler.h typedef struct xid_t XID;

xid_t是一個(gè)結(jié)構(gòu)體，代碼太多，這里就不貼了

變量備注 X/Open XA transaction identification to identify a transaction branch 打開(kāi)分布式事務(wù)的標(biāo)識(shí)，以便區(qū)分事務(wù)分支

變量24 commit_lsn

變量類(lèi)型

/* Type used for all log sequence number storage and arithmetics */ typedef ib_uint64_t lsn_t;

變量備注

lsn at the time of the commit lsn提交的時(shí)間

變量25 table_id

變量類(lèi)型 table_id_t

變量備注 Table to drop iff dict_operation == TRX_DICT_OP_TABLE, or 0

變量26 mysql_thd

變量類(lèi)型 THD* 這是一個(gè)超級(jí)大的結(jié)構(gòu)體，詳情需要看代碼

變量備注

MySQL thread handle corresponding to this trx, or NULL 對(duì)應(yīng)這個(gè)trx的MySQL線(xiàn)程句柄，或NULL

變量27 mysql_log_file_name

變量類(lèi)型 const char*

變量備注

if MySQL binlog is used, this field contains a pointer to the latest file name; this is NULL if binlog is not used

如果使用MySQL binlog，此字段包含指向最新文件名的指針; 如果不使用binlog，則為NULL

變量28 mysql_log_offset

變量類(lèi)型 ib_int64_t

變量備注

if MySQL binlog is used, this field contains the end offset of the binlog entry

如果使用MySQL binlog，則此字段包含binlog條目的結(jié)束偏移量

變量29 n_mysql_tables_in_use

變量類(lèi)型 ulint

變量備注 number of Innobase tables used in the processing of the current SQL statement in MySQL

MySQL中處理當(dāng)前SQL語(yǔ)句時(shí)使用的Innobase表的數(shù)量

變量30 mysql_n_tables_locked

變量類(lèi)型 ulint

變量備注

how many tables the current SQL statement uses, except those in consistent read

變量31 trx_list

變量類(lèi)型 UT_LIST_NODE_T(trx_t)

#define UT_LIST_NODE_T(TYPE) \ struct { \TYPE* prev; /*!< pointer to the previous node, \NULL if start of list */ \TYPE* next; /*!< pointer to next node, NULL if end of list */\ }

變量備注

list of transactions; protected by trx_sys->mutex. The same node is used for both trx_sys_t::ro_trx_list and trx_sys_t::rw_trx_list

事務(wù)列表：受trx_sys->mutex保護(hù)。 同樣的節(jié)點(diǎn)用于trx_sys_t :: ro_trx_list和trx_sys_t :: rw_trx_list

變量32 mysql_trx_list

變量類(lèi)型 UT_LIST_NODE_T(trx_t)

變量備注

list of transactions created for MySQL; protected by trx_sys->mutex

變量33 error_state

變量類(lèi)型 dberr_t

變量備注

0 if no error, otherwise error number; NOTE That ONLY the thread doing the transaction is allowed to set this field: this is NOT protected by any mutex

錯(cuò)誤碼 注意只有執(zhí)行事務(wù)的線(xiàn)程才允許設(shè)置此字段 這不受任何互斥保護(hù)

變量34 dict_index_t*error_info

變量類(lèi)型 const

變量備注

if the error number indicates a duplicate key error, a pointer to the problematic index is stored here 如果錯(cuò)誤號(hào)表示重復(fù)鍵錯(cuò)誤，則在此存儲(chǔ)指向有問(wèn)題索引的指針

變量35 error_key_num

變量類(lèi)型 ulint

變量備注

if the index creation fails to a duplicate key error, a mysql key number of that index is stored here

如果索引創(chuàng)建失敗，重復(fù)的鍵錯(cuò)誤，該索引的mysql鍵號(hào)存儲(chǔ)在這里

變量36 sess

變量類(lèi)型 sess_t*

/* The session handle. This data structure is only used by purge and is not really necessary. We should get rid of it. */ struct sess_t{ulint state; /*!< state of the session */trx_t* trx; /*!< transaction object permanentlyassigned for the session: thetransaction instance designated by thetrx id changes, but the memorystructure is preserved */UT_LIST_BASE_NODE_T(que_t)graphs; /*!< query graphs belonging to thissession */ };

變量備注

session of the trx, NULL if none

變量37 graph

變量類(lèi)型que_t*

變量備注

query currently run in the session, or NULL if none; NOTE that the query belongs to the session, and it can survive over a transaction commit, if it is a stored procedure with a COMMIT WORK statement, for instance

查詢(xún)當(dāng)前在運(yùn)行中的會(huì)話(huà)，如果沒(méi)有則為NULL 注意，查詢(xún)屬于會(huì)話(huà)，并且它可以通過(guò)事務(wù)提交存活，如果它是具有COMMIT WORK語(yǔ)句的存儲(chǔ)過(guò)程，例如

變量38 global_read_view_heap

變量類(lèi)型 mem_heap_t*

/* A memory heap is a nonempty linear list of memory blocks */ typedef mem_block_t mem_heap_t;/* A block of a memory heap consists of the info structure followed by an area of memory */ typedef struct mem_block_info_t mem_block_t;mem_block_info_t又是一個(gè)復(fù)雜的結(jié)構(gòu)體

變量備注

memory heap for the global read view 內(nèi)存堆的全局讀取視圖

變量39 global_read_view

變量類(lèi)型 read_view_t* 又是一個(gè)比較復(fù)雜的結(jié)構(gòu)體

一致的讀取視圖關(guān)聯(lián)到事務(wù)或NULL

變量40 read_view

變量類(lèi)型 read_view_t* 變量備注

consistent read view used in the transaction or NULL, this read view if defined can be normal read view associated to a transaction (i.e. same as global_read_view) or read view associated to a cursor

一致的讀取視圖用于事務(wù)或NULL，此讀取視圖如果定義可以是與事務(wù)相關(guān)聯(lián)的正常讀取視圖（即與global_read_view相同）或與光標(biāo)相關(guān)聯(lián)的讀取視圖

變量41 trx_savepoints

變量類(lèi)型 UT_LIST_BASE_NODE_T(trx_named_savept_t)

變量備注 savepoints set with SAVEPOINT ..., oldest first 使用SAVEPOINT設(shè)置保存點(diǎn)的列表 ...，最舊的放在最前面

變量42 undo_mutex

變量類(lèi)型 ib_mutex_t

變量備注 mutex protecting the fields in this section (down to undo_no_arr), EXCEPT last_sql_stat_start, which can be accessed only when we know that there cannot be any activity in the undo logs!

互斥體保護(hù)此部分中的字段（向下到undo_no_arr），除了 last_sql_stat_start，只有當(dāng)我們知道在撤銷(xiāo)日志中不能有任何活動(dòng)時(shí)才可以訪(fǎng)問(wèn)它們！

變量43 undo_no

變量類(lèi)型undo_no_t

/** Undo number */ typedef ib_id_t undo_no_t;

變量備注

next undo log record number to assign; since the undo log is private for a transaction, this is a simple ascending sequence with no gaps; thus it represents the number of modified/inserted rows in a transaction

分配下一個(gè)撤銷(xiāo)日志記錄號(hào); 因?yàn)槌蜂N(xiāo)日志對(duì)于事務(wù)是私有的，這是一個(gè)沒(méi)有間隙的簡(jiǎn)單升序序列; 因此它表示事務(wù)中修改/插入行的數(shù)量。

變量44 last_sql_stat_start

變量類(lèi)型 trx_savept_t

變量備注 undo_no when the last sql statement was started: in case of an error, trx is rolled back down to this undo number; see note at undo_mutex

當(dāng)最后一個(gè)sql語(yǔ)句啟動(dòng)時(shí)，分配undo_no：在出現(xiàn)錯(cuò)誤的情況下，trx被回滾到這個(gè)撤銷(xiāo)號(hào); 請(qǐng)參見(jiàn)undo_mutex中的注釋

變量45 rseg

變量類(lèi)型 trx_rseg_t* 這又是一個(gè)比較復(fù)雜的結(jié)構(gòu)體，但segement其實(shí)是和Page綁定在一起的， 變量備注

rollback segment assigned to the transaction, or NULL if not assigned yet

回滾段分配給事務(wù)，如果尚未分配，則為NULL

變量46 insert_undo

變量類(lèi)型 trx_undo_t*

變量備注

pointer to the insert undo log, or NULL if no inserts performed yet

指向插入undo日志的指針，如果尚未執(zhí)行插入，則為NULL

變量47 update_undo

變量類(lèi)型 trx_undo_t*

變量備注 pointer to the update undo log, or NULL if no update performed yet

變量48 roll_limit

變量類(lèi)型 undo_no_t

變量備注 least undo number to undo during a rollback

事務(wù)回滾的時(shí)候，最小的回滾數(shù)

變量49 pages_undone

變量類(lèi)型 ulint

變量備注 number of undo log pages undone since the last undo log truncation

自上次撤消日志截?cái)嘁詠?lái)撤銷(xiāo)日志頁(yè)面的數(shù)量

變量50 undo_no_arr

變量類(lèi)型 trx_undo_arr_t*

變量備注 array of undo numbers of undo log records which are currently processed by a rollback operation

撤消日志記錄的撤銷(xiāo)編號(hào)數(shù)組，這些撤消日志記錄當(dāng)前由回滾操作處理

變量51 n_autoinc_rows

變量類(lèi)型ulint

變量備注 no. of AUTO-INC rows required for an SQL statement. This is useful for multi-row INSERTs

SQL語(yǔ)句所需的AUTO-INC行的數(shù)量。 這對(duì)于多行INSERT非常有用

變量52 autoinc_locks

變量類(lèi)型 ib_vector_t*

變量備注

AUTOINC locks held by this transaction. Note that these are also in the lock list trx_locks. This vector needs to be freed explicitly when the trx instance is destroyed. Protected by lock_sys->mutex

此事務(wù)持有的AUTOINC鎖。 注意，這些也在鎖定列表trx_locks中。 當(dāng)trx實(shí)例被銷(xiāo)毀時(shí)，這個(gè)向量需要被明確地釋放。 受lock_sys-> mutex保護(hù)

變量53 read_only

變量類(lèi)型 ibool

變量備注 TRUE if transaction is flagged as a READ-ONLY transaction. if !auto_commit || will_lock > 0 then it will added to the list trx_sys_t::ro_trx_list. A read only transaction will not be assigned an UNDO log. Non-locking auto-commit read-only transaction will not be on either list

如果事務(wù)標(biāo)記為READ-ONLY事務(wù)，則為T(mén)RUE。 if！auto_commit || will_lock> 0，那么它將被添加到列表trx_sys_t :: ro_trx_list。 只讀事務(wù)將不會(huì)被分配UNDO日志。 非鎖定自動(dòng)提交只讀事務(wù)將不在任一列表上

變量54 auto_commit

變量類(lèi)型 ibool

變量備注 TRUE if it is an autocommit

變量55 will_lock

變量類(lèi)型 ulint

變量備注

Will acquire some locks. Increment each time we determine that a lock will be acquired by the MySQL layer

標(biāo)記會(huì)獲得一些鎖。 每次我們確定需要獲取鎖的時(shí)候，將被MySQL層獲取時(shí)遞增

變量56 ddl

變量類(lèi)型 bool

變量備注 true if it is a transaction that is being started for a DDL operation

如果它是為DDL操作啟動(dòng)的事務(wù)，則為true

變量57 fts_trx

變量類(lèi)型 fts_trx_t*

變量類(lèi)型 FTS information, or NULL if transaction hasn't modified tables with FTS indexes (yet)

FTS信息，如果事務(wù)尚未修改具有FTS索引的表（尚未），則為NULL;

變量58 fts_next_doc_id

變量類(lèi)型 doc_id_t

變量備注

The document id used for updates 用于更新的文檔ID

變量59 flush_tables

變量類(lèi)型 ulint

變量備注 if "covering" the FLUSH TABLES",count of tables being flushed

如果“覆蓋”FLUSH TABLES“，則表的計(jì)數(shù)被刷新

變量60 api_trx

變量類(lèi)型 bool

變量備注 trx started by InnoDB API

變量61 api_auto_commit

變量類(lèi)型 bool

變量備注 automatic commit

變量62 read_write

變量類(lèi)型 bool

變量備注 if read and write operation

變量63 detailed_error[256]

變量類(lèi)型char

變量備注 detailed error message for last error, or empty

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