DB_LOGC->get()

#include <db.h>

int
DB_LOGC->get(DB_LOGC *logc, DB_LSN *lsn, DBT *data, u_int32_t flags);  

The DB_LOGC->get() method returns records from the log.

Unless otherwise specified, the DB_LOGC->get() method returns a non-zero error value on failure and 0 on success.

Parameters

lsn

When the flag parameter is set to DB_CURRENT, DB_FIRST, DB_LAST, DB_NEXT or DB_PREV, the lsn parameter is overwritten with the DB_LSN value of the record retrieved. When flag is set to DB_SET, the lsn parameter is the DB_LSN value of the record to be retrieved.

data

The data field of the data structure is set to the record retrieved, and the size field indicates the number of bytes in the record. See DBT for a description of other fields in the data structure. The DB_DBT_MALLOC, DB_DBT_REALLOC and DB_DBT_USERMEM flags may be specified for any DBT used for data retrieval.

flags

The flags parameter must be set to one of the following values:

• DB_CURRENT

  Return the log record to which the log currently refers.

• DB_FIRST

  The first record from any of the log files found in the log directory is returned in the data parameter. The lsn parameter is overwritten with the DB_LSN of the record returned.

  The DB_LOGC->get() method will return DB_NOTFOUND if DB_FIRST is set and the log is empty.

• DB_LAST

  The last record in the log is returned in the data parameter. The lsn parameter is overwritten with the DB_LSN of the record returned.

  The DB_LOGC->get() method will return DB_NOTFOUND if DB_LAST is set and the log is empty.

• DB_NEXT

  The current log position is advanced to the next record in the log, and that record is returned in the data parameter. The lsn parameter is overwritten with the DB_LSN of the record returned.

  If the cursor has not been initialized via DB_FIRST, DB_LAST, DB_SET, DB_NEXT, or DB_PREV, DB_LOGC->get() will return the first record in the log.

  The DB_LOGC->get() method will return DB_NOTFOUND if DB_NEXT is set and the last log record has already been returned or the log is empty.

• DB_PREV

  The current log position is advanced to the previous record in the log, and that record is returned in the data parameter. The lsn parameter is overwritten with the DB_LSN of the record returned.

  If the cursor has not been initialized via DB_FIRST, DB_LAST, DB_SET, DB_NEXT, or DB_PREV, DB_LOGC->get() will return the last record in the log.

  The DB_LOGC->get() method will return DB_NOTFOUND if DB_PREV is set and the first log record has already been returned or the log is empty.

• DB_SET

  Retrieve the record specified by the lsn parameter.

Errors

The DB_LOGC->get() method may fail and return one of the following non-zero errors:

EINVAL

If the DB_CURRENT flag was set and the log cursor has not yet been initialized; the DB_CURRENT, DB_NEXT, or DB_PREV flags were set and the log was opened with the DB_THREAD flag set; the DB_SET flag was set and the specified log sequence number does not appear in the log; or if an invalid flag value or parameter was specified.

Class

DB_ENV, DB_LOGC, DB_LSN

See Also

Logging Subsystem and Related Methods