DbEnv::txn_stat(DB_TXN_STAT **statp, u_int32_t flags);
The DbEnv::txn_stat method returns the transaction subsystem statistics.
The flags value must be set to 0 or
the following value:
- Reset statistics after returning their values.
The DbEnv::txn_stat method creates a statistical structure of type
DB_TXN_STAT and copies a pointer to it into a user-specified memory
Statistical structures are created in allocated memory. If application-specific allocation
routines have been declared (see DbEnv::set_alloc for more
information), they are used to allocate the memory; otherwise, the
library malloc(3) interface is used. The caller is
responsible for deallocating the memory. To deallocate the memory, free
the memory reference; references inside the returned memory need not be
The following DB_TXN_STAT fields will be filled in:
- DbLsn st_last_ckp;
- The LSN of the last checkpoint.
- time_t st_time_ckp;
- The time the last completed checkpoint finished (as the number of seconds
since the Epoch, returned by the IEEE/ANSI Std 1003.1 (POSIX) time interface).
- u_int32_t st_last_txnid;
- The last transaction ID allocated.
- u_int32_t st_maxtxns;
- The maximum number of active transactions possible.
- u_int32_t st_nactive;
- The number of transactions that are currently active.
- u_int32_t st_maxnactive;
- The maximum number of active transactions at any one time.
- u_int32_t st_nbegins;
- The number of transactions that have begun.
- u_int32_t st_naborts;
- The number of transactions that have aborted.
- u_int32_t st_ncommits;
- The number of transactions that have committed.
- u_int32_t st_nrestores;
- The number of transactions that have been restored.
- u_int32_t st_regsize;
- The size of the region.
- u_int32_t st_region_wait;
- The number of times that a thread of control was forced to wait before
obtaining the region lock.
- u_int32_t st_region_nowait;
- The number of times that a thread of control was able to obtain
the region lock without waiting.
- DB_TXN_ACTIVE *st_txnarray;
- A pointer to an array of st_nactive DB_TXN_ACTIVE structures,
describing the currently active transactions. The following fields of
the DB_TXN_ACTIVE structure will be filled in:
- u_int32_t txnid;
- The transaction ID of the transaction.
- u_int32_t parentid;
- The transaction ID of the parent transaction (or 0, if no parent).
- DbLsn lsn;
- The current log sequence number when the transaction was begun.
The DbEnv::txn_stat method either returns a non-zero error value or throws an exception that
encapsulates a non-zero error value on failure, and returns 0 on success.
The DbEnv::txn_stat method may fail and throw an exception or return a non-zero error for errors specified for other Berkeley DB and C library or system methods.
If a catastrophic error has occurred, the DbEnv::txn_stat method may fail and
either return DB_RUNRECOVERY or throw a
in which case all subsequent Berkeley DB calls will fail in the same way.
Transaction Subsystem and Related Methods
Copyright Sleepycat Software