db_stat
db_stat -d file [-fN] [-h home] [-P password] [-s database]
db_stat [-acEelmNrtVxZ] [-C Aclop] [-h home] [-L A] [-M Ah] [-R A]
[-X A] [-P password] The db_stat utility displays statistics for Berkeley DB environments.
The options are as follows:
-a
Display the shared-region allocation lists in addition to the requested statistics. This option only has an effect in combination with one of the uppercase subsystem options (which imply "display all information"); given on its own it is an error. The output is voluminous and is intended for debugging the library's region allocator.
-C
Display detailed information about the locking subsystem.
A
Display all information.
c
Display lock conflict matrix.
l
Display lockers within hash chains.
o
Display lock objects within hash chains.
p
Display locking subsystem parameters.
-c
Display locking subsystem statistics, as described in the DB_ENV->lock_stat() method.
-d
Display database statistics for the specified file, as described in the DB->stat() method.
If the database contains multiple databases and the -s flag is not specified, the statistics are for the internal database that describes the other databases the file contains, and not for the file as a whole.
-E
Display detailed information about the database environment.
-e
Display information about the database environment, including all configured subsystems of the database environment.
-f
Display only those database statistics that can be acquired without traversing the database.
-h
Specify a home directory for the database environment; by default, the current working directory is used.
-l
Display logging subsystem statistics, as described in the DB_ENV->log_stat() method.
-L
Display all logging subsystem statistics.
A
Display all information.
-M
Display detailed information about the cache.
A
Display all information.
h
Display buffers within hash chains.
-m
Display cache statistics, as described in the DB_ENV->memp_stat() method.
-N
Do not acquire shared region mutexes while running. Other problems, such as potentially fatal errors in Berkeley DB, will be ignored as well. This option is intended only for debugging errors, and should not be used under any other circumstances.
-P
Specify an environment password. Although Berkeley DB utilities overwrite password strings as soon as possible, be aware there may be a window of vulnerability on systems where unprivileged users can see command-line arguments or where utilities are not able to overwrite the memory containing the command-line arguments.
-R
Display detailed information about the replication subsystem.
A
Display all information.
-r
Display replication statistics, as described in in the DB_ENV->rep_stat() method.
-s
Display statistics for the specified database contained in the file specified with the -d flag.
-t
Display transaction subsystem statistics, as described in the DB_ENV->txn_stat() method.
-V
Write the library version number to the standard output, and exit.
-x
Display mutex subsystem statistics, as described in the DB_ENV->mutex_stat() method.
-X
Display detailed information about the mutex subsystem.
A
Display all information.
-Z
Reset the statistics after reporting them; valid only with the -C, -c, -E, -e, -L, -l, -M, -m, -R, -r, and -t options.
Values normally displayed in quantities of bytes are displayed as a combination of gigabytes (GB), megabytes (MB), kilobytes (KB), and bytes (B). Otherwise, values smaller than 10 million are displayed without any special notation, and values larger than 10 million are displayed as a number followed by "M".
Deployment health lines
The -c (locking), -t (transaction), and -x (mutex) outputs each end with a Deployment health (alarm on these): block. These are the lines to monitor for shared-region resource exhaustion — a failure that otherwise surfaces only as a bare ENOMEM from a later, unrelated operation:
$ db_stat -h ENV -c | tail -5
Deployment health (alarm on these):
194/4000 Locker slots in use (4% utilized)
11/4000 Lock object slots in use (0% utilized)
194/4000 Lock slots in use (4% utilized)
194/300 SSI committed-reader SIREAD markers live (64% utilized)
$ db_stat -h ENV -t | grep -A3 'Deployment health'
Deployment health (alarm on these):
0/2000 Active transaction slots in use (0% utilized)
213/2000 Snapshot txn details retained (MVCC/SSI) (10% utilized)
$ db_stat -h ENV -x | grep -A2 'Deployment health'
Deployment health (alarm on these):
845/10000 Mutex slots in use (8% utilized)Each line reports in-use/maximum followed by the utilization percentage. A resource for which no maximum has been configured reports <n>/unlimited ... (no maximum configured): it will grow until the region itself is exhausted, so no meaningful ratio exists. Configuring the maxima is a prerequisite for alarming on these numbers.
The same values are available programmatically, without parsing this output, through DB_ENV->lock_stat(), DB_ENV->txn_stat(), and DB_ENV->mutex_stat(). Note that -Z (DB_STAT_CLEAR) resets the high-water marks these alarms rely on; monitoring should not use it.
For the recommended thresholds, what each signal means, and the remedy for each, see the Deployment health: what to alarm on section of the Berkeley DB Programmer's Reference Guide.
The db_stat utility may be used with a Berkeley DB environment (as described for the -h option, the environment variable DB_HOME, or because the utility was run in a directory containing a Berkeley DB environment). In order to avoid environment corruption when using a Berkeley DB environment, db_stat should always be given the chance to detach from the environment and exit gracefully. To cause db_stat to release all environment resources and exit cleanly, send it an interrupt signal (SIGINT).
The db_stat utility exits 0 on success, and >0 if an error occurs.
For information on the statistics feature for Berkeley DB SQL interface, see Command Line Features Unique to dbsql.
Environment Variables
DB_HOME
If the -h option is not specified and the environment variable DB_HOME is set, it is used as the path of the database home, as described in the DB_ENV->open() method.