#include <db_cxx.h> int Db::put(DbTxn *txnid, Dbt *key, Dbt *data, u_int32_t flags);
The Db::put() method stores key/data
pairs in the database. The default behavior of the
Db::put() function is to enter the new
key/data pair, replacing any previously existing key if duplicates
are disallowed, or adding a duplicate data item if duplicates are
allowed. If the database supports duplicates, the
Db::put() method adds the new data value
at the end of the duplicate set. If the database supports sorted
duplicates, the new data value is inserted at the correct sorted
location.
Unless otherwise specified, the
Db::put()
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.
If the operation is part of an application-specified transaction, the txnid parameter is a transaction handle returned from DbEnv::txn_begin() ; if the operation is part of a Berkeley DB Concurrent Data Store group, the txnid parameter is a handle returned from DbEnv::cdsgroup_begin() ; otherwise NULL. If no transaction handle is specified, but the operation occurs in a transactional database, the operation will be implicitly transaction protected.
The key Dbt operated on.
If creating a new record in a Heap database, the
key Dbt
must be empty. The put
method will return the new record's
Record ID (RID)
in the key Dbt.
The data Dbt operated on.
The flags parameter must be set to 0 or one of the following values:
Append the key/data pair to the end of the database. For the DB_APPEND flag to be specified, the underlying database must be a Heap, Queue or Recno database. The record number allocated to the record is returned in the specified key.
There is a minor behavioral difference between the Recno
and Queue access methods for the DB_APPEND flag. If a
transaction enclosing a
Db::put() operation with the
DB_APPEND flag aborts, the record number may be
reallocated in a subsequent DB_APPEND
operation if you are using the Recno access method, but it
will not be reallocated if you are using the Queue access
method.
For a Heap database, if the put operation results in the creation of a new record, then this flag is required.
In the case of the Btree and Hash access methods, enter the new key/data pair only if it does not already appear in the database.
The DB_NODUPDATA flag may only be specified if the underlying database has been configured to support sorted duplicates. The DB_NODUPDATA flag may not be specified to the Queue or Recno access methods.
The Db::put() method will return
DB_KEYEXIST
if DB_NODUPDATA is set and the key/data pair already appears in the
database.
Enter the new key/data pair only if the key does
not already appear in the database. The
Db::put() method call
with the DB_NOOVERWRITE flag set will fail if the
key already exists in the database, even if the
database supports duplicates.
The Db::put() method will return
DB_KEYEXIST
if DB_NOOVERWRITE is set and the key already appears in the database.
This enforcement of uniqueness of keys applies only to the primary key. The behavior of insertions into secondary databases is not affected by the DB_NOOVERWRITE flag. In particular, the insertion of a record that would result in the creation of a duplicate key in a secondary database that allows duplicates would not be prevented by the use of this flag.
Put multiple data items using keys from the buffer to which the key parameter refers and data values from the buffer to which the data parameter refers.
To put records in bulk with the btree or hash access methods, construct bulk buffers in the key and data Dbt using DbMultipleDataBuilder. To put records in bulk with the recno or queue access methods, construct bulk buffers in the data Dbt as before, but construct the key Dbt using DbMultipleRecnoDataBuilder with a data size of zero.
A successful bulk operation is logically equivalent to a loop through each key/data pair, performing a Db::put() for each one.
See DBT and Bulk Operations for more information on working with bulk updates.
The DB_MULTIPLE flag may only be
used alone, or with the
DB_OVERWRITE_DUP option.
Put multiple data items using keys and data from the buffer to which the key parameter refers.
To put records in bulk with the btree or hash access methods, construct a bulk buffer in the key Dbt using DbMultipleKeyDataBuilder. To put records in bulk with the recno or queue access methods, construct a bulk buffer in the key Dbt using DbMultipleRecnoDataBuilder.
See DBT and Bulk Operations for more information on working with bulk updates.
The DB_MULTIPLE_KEY flag may
only be used alone, or with the
DB_OVERWRITE_DUP option.
Ignore duplicate records when overwriting records in a database configured for sorted duplicates.
Normally, if a database is configured for sorted duplicates, an attempt to put a record that compares identically to a record already existing in the database will fail. Using this flag causes the put to silently proceed, without failure.
This flag is extremely useful when performing bulk
puts (using the DB_MULTIPLE or
DB_MULTIPLE_KEY flags).
Depending on the number of records you are writing
to the database with a bulk put, you may not want
the operation to fail in the event that a
duplicate record is encountered. Using this flag
along with the DB_MULTIPLE or
DB_MULTIPLE_KEY flags allows
the bulk put to complete, even if a duplicate
record is encountered.
This flag is also useful if you are using a custom comparison function that compares only part of the data portion of a record. In this case, two records can compare equally when, in fact, they are not equal. This flag allows the put to complete, even if your custom comparison routine claims the two records are equal.
The Db::put()
method may fail and throw a DbException
exception, encapsulating one of the following non-zero errors, or return one
of the following non-zero errors:
A foreign key constraint violation has occurred. This can be caused by one of two things:
An attempt was made to add a record to a constrained database, and the key used for that record does not exist in the foreign key database.
DB_FOREIGN_ABORT was declared for a foreign key database, and then subsequently a record was deleted from the foreign key database without first removing it from the constrained secondary database.
An attempt was made to add or update a record in a Heap database. However, the size of the database was constrained using the Db::set_heapsize() method, and that limit has been reached.
A transactional database environment operation was selected to resolve a deadlock.
DbDeadlockException is thrown if
your Berkeley DB API is configured to throw exceptions.
Otherwise, DB_LOCK_DEADLOCK is returned.
A Berkeley DB Concurrent Data Store database environment configured for lock timeouts was unable to grant a lock in the allowed time.
You attempted to open a database handle that is configured for no waiting exclusive locking, but the exclusive lock could not be immediately obtained. See Db::set_lk_exclusive() for more information.
DbLockNotGrantedException is thrown if
your Berkeley DB API is configured to throw exceptions.
Otherwise, DB_LOCK_NOTGRANTED is returned.
When a client synchronizes with the master, it is possible for committed
transactions to be rolled back. This invalidates all the database and cursor
handles opened in the replication environment. Once this occurs, an attempt to use
such a handle will
throw a DbRepHandleDeadException (if
your application is configured to throw exceptions), or
return DB_REP_HANDLE_DEAD.
The application will need to discard the handle and open a new one in order to
continue processing.
The operation was blocked by client/master synchronization.
DbDeadlockException is thrown if
your Berkeley DB API is configured to throw exceptions.
Otherwise, DB_REP_LOCKOUT is returned.
If a record number of 0 was specified; an attempt was made to add a record to a fixed-length database that was too large to fit; an attempt was made to do a partial put on a database not configured for it (such as a database configured for duplicate records); an attempt was made to add a record to a secondary index; or if an invalid flag value or parameter was specified.