Berkeley DB: DbEnv::txn_stat
Description: Berkeley DB: An embedded database programmatic toolkit.
Keywords: embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++

### DbEnv::txn_stat |

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###

    #include <db_cxx.h>

    int
    DbEnv::txn_stat(DB_TXN_STAT **statp, u_int32_t flags);

    int
    DbEnv::txn_stat_print(u_int32_t flags);

### Description: DbEnv::txn_stat

The DbEnv::txn_stat method returns the transaction subsystem statistics.

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 location.

Statistical structures are stored 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 standard C library malloc(3) 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 individually freed.

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 function).
u_int32_t st_last_txnid;
  The last transaction ID allocated.
u_int32_t st_maxtxns;
  The maximum number of active transactions configured.
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.
roff_t st_regsize;
  The size of the region, in bytes.
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.
  u_int32_t xa_status;
    If the transaction is an XA transaction, the status of the transaction, otherwise 0.
  u_int8_t xid[DB_XIDDATASIZE];
    If the transaction is an XA transaction, the transaction's XA ID.

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.

### Parameters

flags
  The flags parameter must be set to 0 or the following value:
  DB_STAT_CLEAR
    Reset statistics after returning their values.
statp
  The statp parameter references memory into which a pointer to the allocated statistics structure is copied.

### Errors

The DbEnv::txn_stat method may fail and throw DbException, encapsulating one of the following non-zero errors, or return one of the following non-zero errors:

EINVAL
  An invalid flag value or parameter was specified.

### Description: DbEnv::txn_stat_print

The DbEnv::txn_stat_print method returns the transaction subsystem statistical information, as described for the DbEnv::txn_stat method. The information is printed to a specified output channel (see the DbEnv::set_msgfile method for more information), or passed to an application callback function (see the DbEnv::set_msgcall method for more information).

The DbEnv::txn_stat_print method may not be called before the DbEnv::open method has been called.

The DbEnv::txn_stat_print 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.

### Parameters

flags
  The flags parameter must be set to 0 or the following value:
  DB_STAT_ALL
    Display all available information.

### Class

DbEnv, DbTxn

### See Also

Transaction Subsystem and Related Methods`

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