Berkeley DB: DB->close
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->close |

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    #include <db.h>

    int
    DB->close(DB *db, u_int32_t flags);

# Description

The DB->close method flushes any cached database information to disk, closes any open cursors, frees any allocated resources, and closes any underlying files. Because key/data pairs are cached in memory, failing to sync the file with the DB->close or DB->sync method may result in inconsistent or lost information.

The flags value must be set to 0 or by bitwise inclusively OR'ing together one or more of the following values:

DB_NOSYNC
  Do not flush cached information to disk. The DB_NOSYNC flag is a dangerous option. It should be set only if the application is doing logging (with transactions) so that the database is recoverable after a system or application crash, or if the database is always generated from scratch after any system or application crash.

  It is important to understand that flushing cached information to disk only minimizes the window of opportunity for corrupted data. Although unlikely, it is possible for database corruption to happen if a system or application crash occurs while writing data to the database. To ensure that database corruption never occurs, applications must either: use transactions and logging with automatic recovery; use logging and application-specific recovery; or edit a copy of the database, and once all applications using the database have successfully called DB->close, atomically replace the original database with the updated copy.

When multiple threads are using the DB concurrently, only a single thread may call the DB->close method.

The DB handle may not be accessed again after DB->close is called, regardless of its return.

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

# Errors

The DB->close method may fail and return a non-zero error for the following conditions:

EINVAL
  An invalid flag value or parameter was specified.

The DB->close method may fail and return a non-zero error for errors specified for other Berkeley DB and C library or system functions. If a catastrophic error has occurred, the DB->close method may fail and return DB_RUNRECOVERY, 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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