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DbLogc::logc_get
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#include <db_cxx.h>
int
DbLogc::get(DbLsn *lsn, Dbt *data, u_int32_t flags);
Description
The DbLogc::logc_get method retrieve records from the log according to the
lsn and flags arguments.
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.
The flags value must be set to one of the following values:
- DB_CHECKPOINT
- The last record written with the DB_CHECKPOINT flag specified to the
DbEnv::log_put method is returned in the data argument. The
lsn argument is overwritten with the DbLsn of the record
returned. If no record has been previously written with the DB_CHECKPOINT
flag specified, the first record in the log is returned.
If the log is empty, the DbLogc::logc_get method will return DB_NOTFOUND.
- DB_FIRST
- The first record from any of the log files found in the log directory
is returned in the data argument.
The lsn argument is overwritten with the DbLsn of the
record returned.
If the log is empty, the DbLogc::logc_get method will return DB_NOTFOUND.
- DB_LAST
- The last record in the log is returned in the data argument.
The lsn argument is overwritten with the DbLsn of the
record returned.
If the log is empty, the DbLogc::logc_get method will return DB_NOTFOUND.
- DB_NEXT, DB_PREV
- The current log position is advanced to the next (previous) record in
the log, and that record is returned in the data argument. The
lsn argument is overwritten with the DbLsn of the record
returned.
If the pointer has not been initialized via DB_FIRST, DB_LAST, DB_SET,
DB_NEXT, or DB_PREV, DbLogc::logc_get will return the first (last) record
in the log. If the last (first) log record has already been returned
or the log is empty, the DbLogc::logc_get method will return DB_NOTFOUND.
If the log was opened with the DB_THREAD flag set, calls to
DbLogc::logc_get with the DB_NEXT (DB_PREV) flag set will return
EINVAL.
- DB_CURRENT
- Return the log record to which the log currently refers.
If the log pointer has not been initialized via DB_FIRST, DB_LAST,
DB_SET, DB_NEXT, or DB_PREV, or if the log was opened with the DB_THREAD
flag set, DbLogc::logc_get will return EINVAL.
- DB_SET
- Retrieve the record specified by the lsn argument. If the
specified DbLsn is invalid (for example, it does not appear in
the log) DbLogc::logc_get will return EINVAL.
Otherwise, the DbLogc::logc_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.
Errors
The DbLogc::logc_get method may fail and throw an exception or return a non-zero error for the following conditions:
- EINVAL
- An invalid flag value or parameter was specified.
The DB_CURRENT flag was set and the log pointer had not yet been
initialized.
The DB_SET flag was set and the specified log sequence number does not
exist.
The DbLogc::logc_get 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 DbLogc::logc_get method may fail and either
return DB_RUNRECOVERY or throw an exception encapsulating
DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail
in the same way.
Class
DbEnv
See Also
DbEnv::set_lg_bsize,
DbEnv::set_lg_dir,
DbEnv::set_lg_max,
DbEnv::set_lg_regionmax,
DbEnv::log_archive,
DbEnv::log_compare,
DbEnv::log_cursor,
DbEnv::log_file,
DbEnv::log_flush,
DbEnv::log_put,
DbEnv::log_register,
DbEnv::log_stat,
DbEnv::log_unregister,
DbLogc::logc_close
and
DbLogc::logc_get.
Copyright Sleepycat Software
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