nosync.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: nosync.so,v 1.7 2004/09/28 14:13:09 bostic Exp $])

m4_ref_title(Upgrading m4_db Applications,
    Release 4.2: Client replication environments,,
    upgrade.4.2/repinit, upgrade.4.2/tcl)

m4_p([dnl
In previous m4_db releases, replication clients always behaved as if
m4_ref(DB_TXN_NOSYNC) behavior was configured, that is, clients would
not write or synchronously flush their log when receiving a transaction
commit or prepare message.  However, applications needing a high level
of transactional guarantee may need a write and synchronous flush on
the client.  By default in the m4_db 4.2 release, client database
environments write and synchronously flush their logs when receiving a
transaction commit or prepare message.  Applications not needing such
a high level of transactional guarantee should use the environment's
m4_ref(DB_TXN_NOSYNC) flag to configure their client database
environments to not do the write or flush on transaction commit, as this
will increase their performance.  Regardless of the setting of the
m4_ref(DB_TXN_NOSYNC) flag, clients will always write and flush on
transaction prepare.])

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