Berkeley DB: Db::put
Description: Berkeley DB: An embedded database programmatic toolkit.
Keywords: embedded,database,programmatic,toolkit,b+tree,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,java,C,C++

# Db::put |

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    #include <db_cxx.h>

    int
    Db::put(DbTxn *txnid, Dbt *key, Dbt *data, u_int32_t flags);

# Description

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.

If the operation is to be transaction-protected (other than by specifying the DB_AUTO_COMMIT flag), the txnid parameter is a transaction handle returned from DbEnv::txn_begin; otherwise, NULL.

The flags value must be set to 0 or one of the following values:

DB_APPEND
  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 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 decremented (and later reallocated by a subsequent DB_APPEND operation) by the Recno access method, but will not be decremented or reallocated by the Queue access method.

DB_NODUPDATA
  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. If the key/data pair already appears in the database, DB_KEYEXIST is returned. 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.

DB_NOOVERWRITE
  Enter the new key/data pair only if the key does not already appear in the database. If the key already appears in the database, DB_KEYEXIST is returned. Even if the database allows duplicates, a call to Db::put with the DB_NOOVERWRITE flag set will fail if the key already exists in the database.

In addition, the following flag may be set by bitwise inclusively OR'ing it into the flags parameter:

DB_AUTO_COMMIT
  Enclose the Db::put call within a transaction. If the call succeeds, changes made by the operation will be recoverable. If the call fails, the operation will have made no changes.

Otherwise, 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.

# Errors

The Db::put method may fail and throw an exception or return a non-zero error for the following conditions:

EACCES
  An attempt was made to modify a read-only database.

EINVAL
  An invalid flag value or parameter was specified.

  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.

  An attempt was made to add a record to a secondary index.

ENOSPC
  A btree exceeded the maximum btree depth (255).

If the operation was selected to resolve a deadlock, the Db::put method will fail and and either return DB_LOCK_DEADLOCK or throw a DbDeadlockException exception.

The Db::put 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 Db::put method may fail and either return DB_RUNRECOVERY or throw a DbRunRecoveryException, in which case all subsequent Berkeley DB calls will fail in the same way.

# Class

Db

# See Also

Databases and Related Methods`

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