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The dbrepack utility allows to repack a database to reclaim disk space
occupied by deleted records. Without repacking, deleted records are
re-used but the disk space is not freed for use by other data sets or
databases.
The dbrepack utility is an "offline utility" that directly accesses the
database server volume files and may only be used when the database
server is not active (or in online-backup mode when dbrepack
is used in read-only mode).
dbrepack [options] database [set ...]
options:
-help - show usage (this list)
-u user - set user name
-p pswd - set password
-c cfg - server configuration file
-b size - Buffer cache size (MB)
-v - verbose output
-w - enable write mode
-m mb - max. amount of memory to postpone FTS data processing
-P pct - skip set unless at least pct% of disk space reclaimable
-S mb - skip set unless at least mb MB disk space reclaimable
-M - use master key
By default dbrepack runs in read-only mode and analyzes the specified
database unless the -w option is specified.
The option -v enables additional progress messages.
The -c option is used to specify the eloqdb.cfg file for the server instance.
It defaults to the eloqdb.cfg file in the Eloquence config directory.
The -m option is used to specify the size of a scratch memory pool that
is used to collect moved record numbers that have keyword indexes. This
is subsequently used to update the FTS index. As this may cause some I/O
(but noticeably less than re-building the FTS index) it is done in batches.
The default value is zero. It indicates to use the value configured in the
server
config [config] RestructMemLimit value (defaults to 100 MB).
Otherwise, it specifies the size of the memory pool size in MB and must be
between 1 and 2047.
The -M option indicates to request the master key to support encrypted
databases. When the -M command line option is present, the EQ_MKEYID
and EQ_MKEYFILE environment variables are used to obtain the master
key(s) to access encrypted data (requires interactive entry of the pass-phrase).
The dbrepack utility operates in two phases. In the first phase it scans
the table to create a region map of gaps and used records. This map is
used in phase two to move records from the end (highest record number) to
the front until any gaps are filled. This requires updating any chains and
indexes.
- dbrepack accesses the database volume files.
Consequently, the database server may not be active.
The dbrepack read-only mode may be used while the server is in online
backup mode.
- dbrepack in write mode modifies the database volume files and will
most likely leave the database in a corrupted state upon failure.
Please make sure you have a current backup.
- Running dbrepack in write mode will invalidate replication and
forward recovery.
The example below shows running dbrepack to analyze a database.
$ dbrepack -c eloqdb.cfg -v toydb
Running in Read-Only mode
PRODUCTS : 2.4 MB reclaimable (96.8%), 1 records repackable (9.1%)
CUSTOMERS : no space reclaimable
ORDER-MASTER : 0.1 MB reclaimable (45.0%), no records repackable
INVOICES : no space reclaimable
ORDERS : 8.4 MB reclaimable (17.2%), 4934 records repackable (12.5%)
ORDER-DETAILS : no space reclaimable
Total : 10.9 MB reclaimable (21.1%)
The reclaimable disk space indicates the disk space that could be reclaimed by
repacking a data set. The number of repackable records depends on the number
of gaps found in the data set.
Reclaiming the disk space for deleted records is possible but not
recommended unless there is a good cause. Typically deleted records
will be re-used in the course of the year and disk space is no
longer as limited as it used to be. So one needs to weight the
potential efficiency gains by packing the database against the
procedure effort.
To use dbrepack with B.08.20, please make sure you have the dbrepack
patch PE82-1502090 installed (or superseding). This patch is part of
the B.08.20 patch bundle.
The most recent dbrepack patch is PE82-1609260 at this time which is
_significantly_ faster (and better).
Please keep in mind that
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Any disk space reclaimed by dbrepack does not shrink the database
volume files but is made available in the volume file for other use.
If shrinking the volume files is a requirement then the procedure is
to repack the databases first, store them in an archive (dbstore),
create a new set of volume files and then restore them (dbctl
dbrestore).
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A backup is mandatory when using dbrepack. One backup needs to be
taken before using dbrepack. If dbrepack encounters a problem the
database is corrupted and can't be repaired.
Once dbrepack is completed, another backup is necessary as dbrepack
does _not_ update the forward log files and the previous backup and
forward log files will no longer apply.
dbrepack utility (B.08.20
release notes)
dbrepack patch PE82-1609260 (beta)
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