sync.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: sync.so,v 10.18 2003/10/18 19:15:53 bostic Exp $])

m4_ref_title(Access Methods, Flushing the database cache,
    flushing the database @cache, am/verify, am/close)

m4_p([dnl
The m4_refT(dbh_sync) flushes all modified records from the database
cache to disk.])

m4_p([dnl
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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