Обсуждение: checkpoint_segments

postgresql 8.1.0

Hi,

I have checkpoint_segments set to 18, yet I have 38 segmnet files in
pg_xlog.  Is there a reason for that?

Thanks in advance,
~DjK

# WRITE AHEAD LOG
#---------------------------------------------------------------------------

# - Settings -

#fsync = on                       # turns forced synchronization on or off
#wal_sync_method = fsync  # the default is the first option
                                        # supported by the operating system:
                                        #   open_datasync
                                        #   fdatasync
                                        #   fsync
                                        #   fsync_writethrough
                                        #   open_sync
#full_page_writes = on                  # recover from partial page writes
#wal_buffers = 8                        # min 4, 8KB each
wal_buffers = 16                        # min 4, 8KB each
#commit_delay = 0                       # range 0-100000, in microseconds
#commit_siblings = 5                    # range 1-1000

# - Checkpoints -

#checkpoint_segments = 3                # in logfile segments, min 1, 16MB
each
checkpoint_segments = 18                # in logfile segments, min 1, 16MB
each
#checkpoint_timeout = 300               # range 30-3600, in seconds
#checkpoint_warning = 30                # in seconds, 0 is off

"Mr. Dan" <bitsandbytes88@hotmail.com> writes:
> I have checkpoint_segments set to 18, yet I have 38 segmnet files in
> pg_xlog.  Is there a reason for that?

The normal steady state is about 2N segment files, because we keep the
last two checkpoints' worth of WAL data.

            regards, tom lane