Berkeley DB: DB_ENV->txn_recover
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_ENV->txn_recover |

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###

    #include <db.h>

    int
    DB_ENV->txn_recover(DB_ENV *dbenv, DB_PREPLIST preplist[],
        long count, long *retp, u_int32_t flags);

### Description: DB_ENV->txn_recover

Database environment recovery restores transactions that were prepared, but not yet resolved at the time of the system shut down or crash, to their state prior to the shut down or crash, including any locks previously held. The DB_ENV->txn_recover method returns a list of those prepared transactions.

The DB_ENV->txn_recover method should only be called after the environment has been recovered.

Multiple threads of control may call DB_ENV->txn_recover, but only one thread of control may resolve each returned transaction, that is, only one thread of control may call DB_TXN->commit or DB_TXN->abort on each returned transaction. Callers of DB_ENV->txn_recover must call DB_TXN->discard to discard each transaction they do not resolve.

On return from DB_ENV->txn_recover, the preplist parameter will be filled in with a list of transactions that must be resolved by the application (committed, aborted or discarded). The preplist parameter is a structure of type DB_PREPLIST; the following DB_PREPLIST fields will be filled in:

DB_TXN * txn;
  The transaction handle for the transaction.
u_int8_t gid[DB_XIDDATASIZE];
  The global transaction ID for the transaction. The global transaction ID is the one specified when the transaction was prepared. The application is responsible for ensuring uniqueness among global transaction IDs.

The DB_ENV->txn_recover method returns a non-zero error value on failure and 0 on success.

### Parameters

count
  The count parameter specifies the number of available entries in the passed-in preplist array. The retp parameter returns the number of entries DB_ENV->txn_recover has filled in, in the array.
flags
  The flags parameter must be set to one of the following values:
  DB_FIRST
    Begin returning a list of prepared, but not yet resolved transactions. Specifying this flag begins a new pass over all prepared, but not yet completed transactions, regardless of whether they have already been returned in previous calls to DB_ENV->txn_recover. Calls to DB_ENV->txn_recover from different threads of control should not be intermixed in the same environment.
  DB_NEXT
    Continue returning a list of prepared, but not yet resolved transactions, starting where the last call to DB_ENV->txn_recover left off.
preplist
  The preplist parameter references memory into which the list of transactions to be resolved by the application is copied.

### Class

DB_ENV, DB_TXN

### See Also

Transaction Subsystem and Related Methods`

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