Berkeley DB: DbLogc::get
Description: Berkeley DB: An embedded database programmatic toolkit.
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### DbLogc::get |

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###

    #include <db_cxx.h>

    int
    DbLogc::get(DbLsn *lsn, Dbt *data, u_int32_t flags);

### Description: DbLogc::get

The DbLogc::get method returns records from the log.

Unless otherwise specified, the DbLogc::get 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

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 DbLsn of the record returned.

    The DbLogc::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 DbLsn of the record returned.

    The DbLogc::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 DbLsn of the record returned.

    If the cursor has not been initialized via DB_FIRST, DB_LAST, DB_SET, DB_NEXT, or DB_PREV, DbLogc::get will return the first record in the log.

    The DbLogc::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 DbLsn of the record returned.

    If the cursor has not been initialized via DB_FIRST, DB_LAST, DB_SET, DB_NEXT, or DB_PREV, DbLogc::get will return the last record in the log.

    The DbLogc::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.
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 DbLsn value of the record retrieved. When flag is set to DB_SET, the lsn parameter is the DbLsn value of the record to be retrieved.

### Errors

The DbLogc::get method may fail and throw DbException, encapsulating one of the following non-zero errors, or 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

DbEnv, DbLogc, DbLsn

### See Also

Logging Subsystem and Related Methods`

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