The INNODB_LOCKS table contains
information about each lock that an InnoDB
transaction has requested but not yet acquired, and each lock that
a transaction holds that is blocking another transaction.
Table 20.4. INNODB_LOCKS Columns
| Column name | Description |
|---|---|
LOCK_ID | Unique lock ID number, internal to InnoDB. Should be
treated as an opaque string. Although
LOCK_ID currently contains
TRX_ID, the format of the data in
LOCK_ID is not guaranteed to remain the
same in future releases. You should not write programs that
parse the LOCK_ID value. |
LOCK_TRX_ID | ID of the transaction holding this lock. Details about the transaction
can be found by joining with INNODB_TRX on
TRX_ID. |
LOCK_MODE | Mode of the lock. One of S, X,
IS, IX,
S_GAP, X_GAP,
IS_GAP, IX_GAP, or
AUTO_INC for shared, exclusive, intention
shared, intention exclusive row locks, shared and exclusive
gap locks, intention shared and intension exclusive gap locks,
and auto-increment table level lock, respectively. Refer to
the sections Section 13.6.9.1, “InnoDB Lock Modes” and
Section 13.6.9, “The InnoDB Transaction Model and Locking” for information on
InnoDB locking. |
LOCK_TYPE | Type of the lock. One of RECORD or
TABLE for record (row) level or table level
locks, respectively. |
LOCK_TABLE | Name of the table that has been locked or contains locked records. |
LOCK_INDEX | Name of the index if LOCK_TYPE='RECORD', otherwise
NULL. |
LOCK_SPACE | Tablespace ID of the locked record if
LOCK_TYPE='RECORD', otherwise
NULL. |
LOCK_PAGE | Page number of the locked record if
LOCK_TYPE='RECORD', otherwise
NULL. |
LOCK_REC | Heap number of the locked record within the page if
LOCK_TYPE='RECORD', otherwise
NULL. |
LOCK_DATA | Primary key of the locked record if
LOCK_TYPE='RECORD', otherwise
NULL. This column contains the value(s) of
the primary key column(s) in the locked row, formatted as a
valid SQL string (ready to be copied to SQL commands). If
there is no primary key then the InnoDB
internal unique row ID number is used. When the page
containing the locked record is not in the buffer pool (in the
case that it was paged out to disk while the lock was held),
InnoDB does not fetch the page from disk,
to avoid unnecessary disk operations. Instead,
LOCK_DATA is set to
NULL. |
Notes:
Use this table to help diagnose performance problems that occur during times of heavy concurrent load. For usage information, see Section 13.7.6.2.4, “Using the Transaction Information Schema Tables”.