config.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: config.so,v 10.20 2006/08/30 10:08:16 bostic Exp $])

m4_ref_title(Logging Subsystem,
    Configuring logging, @logging configuration, log/intro, log/limits)

m4_p([dnl
The aspects of logging that may be configured are the size of the
logging subsystem's region, the size of the log files on disk and the
size of the log buffer in memory.  The m4_refT(dbenv_set_lg_regionmax)
specifies the size of the logging subsystem's region, in bytes.  The
logging subsystem's default size is approximately 60KB.  This value may
need to be increased if a large number of files are registered with the
m4_db log manager, for example, by opening a large number of m4_db
database files in a transactional application.])

m4_p([dnl
The m4_refT(dbenv_set_lg_max) specifies the individual log file size for
all the applications sharing the m4_db environment.  Setting the log
file size is largely a matter of convenience and a reflection of the
application's preferences in backup media and frequency.  However,
setting the log file size too low can potentially cause problems because
it would be possible to run out of log sequence numbers, which requires
a full archival and application restart to reset.  See
m4_link(M4RELDIR/ref/log/limits, [Log file limits]) for more
information.])

m4_p([dnl
The m4_refT(dbenv_set_lg_bsize) specifies the size of the in-memory log
buffer, in bytes.  Log information is stored in memory until the buffer
fills up or transaction commit forces the buffer to be written to disk.
Larger buffer sizes can significantly increase throughput in the
presence of long-running transactions, highly concurrent applications,
or transactions producing large amounts of data.  By default, the buffer
is approximately 32KB.])

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