close.so

berkeley db 4.6.21的源码。berkeley db是一个简单的数据库管理系统

m4_comment([$Id: close.so,v 10.18 2003/10/18 19:15:51 bostic Exp $])

m4_ref_title(Access Methods,
    Database close, @closing a database, am/sync, am/second)

m4_p([dnl
The m4_refT(dbh_close) closes the m4_ref(Db) database handle.  By
default, m4_ref(dbh_close) also flushes all modified records from the
database cache to disk.])

m4_p([dnl
There is one flag that you can set to customize m4_ref(dbh_close):])

m4_tagbegin
m4_tag([m4_ref(DB_NOSYNC)], [Do not flush cached information to disk.])
m4_tagend

m4_bold([It is important to understand that flushing cached information
to disk only minimizes the window of opportunity for corrupted data, it
does not eliminate the possibility.])

m4_p([dnl
While 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:])

m4_bulletbegin
m4_bullet([Use transactions and logging with automatic recovery.])
m4_bullet([Use logging and application-specific recovery.])
m4_bullet([Edit a copy of the database, and, once all applications
using the database have successfully called m4_ref(dbh_close), use
system operations (for example, the POSIX rename system call) to
atomically replace the original database with the updated copy.])
m4_bulletend

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