Berkeley DB: DB_SEQUENCE->get
Description: Berkeley DB: An embedded database programmatic toolkit.
Keywords: embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++

### DB_SEQUENCE->get |

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###

    #include <db.h>

    int
    DB_SEQUENCE->get(DB_SEQUENCE *seq,
        DB_TXN *txnid, int32_t delta, db_seq_t *retp, u_int32_t flags);

### Description: DB_SEQUENCE->get

The DB_SEQUENCE->get method returns the next available element in the sequence and changes the sequence value by delta. The value of delta must be greater than zero. If there are enough cached values in the sequence handle then they will be returned. Otherwise the next value will be fetched from the database and incremented (decremented) by enough to cover the delta and the next batch of cached values.

If the underlying database handle was opened in a transaction then either the txnid parameter must be a valid transaction handle or DB_AUTO_COMMIT must be specified. The txnid handle must be NULL if the sequence handle was opened with a non-zero cache size.

For maximum concurrency a non-zero cache size should be specified prior to opening the sequence handle and DB_AUTO_COMMIT | DB_TXN_NOSYNC should be specified each DB_SEQUENCE->get method call.

The DB_SEQUENCE->get method will return EINVAL if the record in the database is not a valid sequence record, or the sequences have overflowed is range.

### Parameters

delta
  Specifies the amount to increment or decrement the sequence.
flags
  The flags parameter must be set to 0 or by bitwise inclusively OR'ing together one or more of the following values:
  DB_AUTO_COMMIT
    If the database must be updated the update will be enclosed in a transaction and will be recoverable.
  DB_TXN_NOSYNC
    If a DB_AUTO_COMMIT triggers a transaction, do not synchronously flush the log.
retp
  retp points to the memory to hold the return value from the sequence.
txnid
  If the operation is to be transaction-protected, the txnid parameter is a transaction handle returned from DB_ENV->txn_begin; otherwise, NULL.

### Class

DB_SEQUENCE

### See Also

Sequences and Related Methods`

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