DBEnv¶

Read Oracle documentation for better understanding.

More info…

DBEnv Attributes¶

DBEnv(flags=0)¶: database home directory (read-only)

DBEnv Methods¶

DBEnv(flags=0): Constructor. More info…

set_rpc_server(host, cl_timeout=0, sv_timeout=0)¶: Establishes a connection for this dbenv to a RPC server. This function is not available if linked to Berkeley DB 4.8 or up. More info…

close(flags=0)¶: Close the database environment, freeing resources. More info…

open(homedir, flags=0, mode=0660)¶: Prepare the database environment for use. More info…

log_cursor()¶: Returns a created log cursor. More info…

memp_stat(flags=0)¶

Returns the memory pool (that is, the buffer cache) subsystem statistics.

The returning value is a tuple. The first element is a dictionary with the general stats. The second element is another dictionary, keyed by filename, and the values are the stats for each file.

The first dictionary contains these data:

gbytes Gigabytes of cache (total cache size is st_gbytes + st_bytes).

bytes Bytes of cache (total cache size is st_gbytes + st_bytes).

ncache Number of caches.

max_ncache Maximum number of caches, as configured with the DB_ENV->set_cache_max() method.

regsize Individual cache size, in bytes.

mmapsize Maximum memory-mapped file size.

maxopenfd Maximum open file descriptors.

maxwrite Maximum sequential buffer writes.

maxwrite_sleep Microseconds to pause after writing maximum sequential buffers.

map Requested pages mapped into the process’ address space (there is no available information about whether or not this request caused disk I/O, although examining the application page fault rate may be helpful).

cache_hit Requested pages found in the cache.

cache_miss Requested pages not found in the cache.

page_create Pages created in the cache.

page_in Pages read into the cache.

page_out Pages written from the cache to the backing file.

ro_evict Clean pages forced from the cache.

rw_evict Dirty pages forced from the cache.

page_trickle Dirty pages written using the DB_ENV->memp_trickle() method.

pages Pages in the cache.

page_clean Clean pages currently in the cache.

page_dirty Dirty pages currently in the cache.

hash_buckets Number of hash buckets in buffer hash table.

hash_searches Total number of buffer hash table lookups.

hash_longest Longest chain ever encountered in buffer hash table lookups.

hash_examined Total number of hash elements traversed during hash table lookups.

hash_nowait Number of times that a thread of control was able to obtain a hash bucket lock without waiting.

hash_wait Number of times that a thread of control was forced to wait before obtaining a hash bucket lock.

hash_max_nowait The number of times a thread of control was able to obtain the hash bucket lock without waiting on the bucket which had the maximum number of times that a thread of control needed to wait.

hash_max_wait Maximum number of times any hash bucket lock was waited for by a thread of control.

region_wait Number of times that a thread of control was forced to wait before obtaining a cache region mutex.

region_nowait Number of times that a thread of control was able to obtain a cache region mutex without waiting.

mvcc_frozen Number of buffers frozen.

mvcc_thawed Number of buffers thawed.

mvcc_freed Number of frozen buffers freed.

alloc Number of page allocations.

alloc_buckets Number of hash buckets checked during allocation.

alloc_max_buckets Maximum number of hash buckets checked during an allocation.

alloc_pages Number of pages checked during allocation.

alloc_max_pages Maximum number of pages checked during an allocation.

io_wait Number of operations blocked waiting for I/O to complete.

sync_interrupted Number of mpool sync operations interrupted.

The second dictionary contains these data:

pagesize Page size in bytes.

cache_hit Requested pages found in the cache.

cache_miss Requested pages not found in the cache.

map Requested pages mapped into the process’ address space.

page_create Pages created in the cache.

page_in Pages read into the cache.

page_out Pages written from the cache to the backing file.

More info…

memp_stat_print(flags=0)¶: Displays cache subsystem statistical information. More info…

memp_sync(lsn=None)¶: Flushes modified pages in the cache to their backing files. If provided, lsn is a tuple: (file, offset). More info…

memp_trickle(percent)¶: Ensures that a specified percent of the pages in the cache are clean, by writing dirty pages to their backing files. More info…

remove(homedir, flags=0)¶: Remove a database environment. More info…

dbremove(file, database=None, txn=None, flags=0)¶: Removes the database specified by the file and database parameters. If no database is specified, the underlying file represented by file is removed, incidentally removing all of the databases it contained. More info…

dbrename(file, database=None, newname, txn=None, flags=0)¶: Renames the database specified by the file and database parameters to newname. If no database is specified, the underlying file represented by file is renamed, incidentally renaming all of the databases it contained. More info…

fileid_reset(file, flags=0)¶: All databases contain an ID string used to identify the database in the database environment cache. If a physical database file is copied, and used in the same environment as another file with the same ID strings, corruption can occur. The DB_ENV->fileid_reset method creates new ID strings for all of the databases in the physical file. More info…

get_thread_count()¶: Returns the thread count as set by the DB_ENV->set_thread_count() method. More info…

set_thread_count(count)¶: Declare an approximate number of threads in the database environment. The DB_ENV->set_thread_count() method must be called prior to opening the database environment if the DB_ENV->failchk() method will be used. The DB_ENV->set_thread_count() method does not set the maximum number of threads but is used to determine memory sizing and the thread control block reclamation policy. More info…

set_encrypt(passwd, flags=0)¶: Set the password used by the Berkeley DB library to perform encryption and decryption. More info…

get_encrypt_flags()¶: Returns the encryption flags. More info…

get_intermediate_dir_mode()¶

Returns the intermediate directory permissions.

Intermediate directories are directories needed for recovery. Normally, Berkeley DB does not create these directories and will do so only if the DB_ENV->set_intermediate_dir_mode() method is called.

More info…

set_intermediate_dir_mode(mode)¶

By default, Berkeley DB does not create intermediate directories needed for recovery, that is, if the file /a/b/c/mydatabase is being recovered, and the directory path b/c does not exist, recovery will fail. This default behavior is because Berkeley DB does not know what permissions are appropriate for intermediate directory creation, and creating the directory might result in a security problem.

The DB_ENV->set_intermediate_dir_mode() method causes Berkeley DB to create any intermediate directories needed during recovery, using the specified permissions.

More info…

get_timeout(flags)¶: Returns a timeout value, in microseconds. More info…

set_timeout(timeout, flags)¶: Sets timeout values for locks or transactions in the database environment. More info…

get_mp_max_openfd()¶: Returns the maximum number of file descriptors the library will open concurrently when flushing dirty pages from the cache. More info…

set_mp_max_openfd(max_open_fd)¶: Limits the number of file descriptors the library will open concurrently when flushing dirty pages from the cache. More info…

get_mp_max_write()¶: Returns a tuple with the current maximum number of sequential write operations and microseconds to pause that the library can schedule when flushing dirty pages from the cache. More info…

set_mp_max_write(maxwrite, maxwrite_sleep)¶: Limits the number of sequential write operations scheduled by the library when flushing dirty pages from the cache. More info…

set_shm_key(key)¶: Specify a base segment ID for Berkeley DB environment shared memory regions created in system memory on VxWorks or systems supporting X/Open-style shared memory interfaces; for example, UNIX systems supporting shmget(2) and related System V IPC interfaces. More info…

get_shm_key()¶: Returns the base segment ID. More info…

set_cache_max(gbytes, bytes)¶: Sets the maximum cache size, in bytes. The specified size is rounded to the nearest multiple of the cache region size, which is the initial cache size divided by the number of regions specified to the DB_ENV->set_cachesize() method. If no value is specified, it defaults to the initial cache size. More info…

get_cache_max()¶: Returns the maximum size of the cache as set using the DB_ENV->set_cache_max() method. More info…

set_cachesize(gbytes, bytes, ncache=0)¶: Set the size of the shared memory buffer pool. More info…

get_cachesize()¶: Returns a tuple with the current size and composition of the cache. More info…

set_data_dir(dir)¶: Set the environment data directory. You can call this function multiple times, adding new directories. More info…

get_data_dirs()¶: Return a tuple with the directories. More info…

get_flags()¶: Returns the configuration flags set for a DB_ENV handle. More info…

set_flags(flags, onoff)¶: Set additional flags for the DBEnv. The onoff parameter specifes if the flag is set or cleared. More info…

set_tmp_dir(dir)¶: Set the directory to be used for temporary files. More info…

get_tmp_dir()¶: Returns the database environment temporary file directory. More info…

set_get_returns_none(flag)¶

By default when DB.get or DBCursor.get, get_both, first, last, next or prev encounter a DB_NOTFOUND error they return None instead of raising DBNotFoundError. This behaviour emulates Python dictionaries and is convenient for looping.

You can use this method to toggle that behaviour for all of the aformentioned methods or extend it to also apply to the DBCursor.set, set_both, set_range, and set_recno methods. Supported values of flag:

0 all DB and DBCursor get and set methods will raise a DBNotFoundError rather than returning None.
1 Default in module version <4.2.4 The DB.get and DBCursor.get, get_both, first, last, next and prev methods return None.
2 Default in module version >=4.2.4 Extends the behaviour of 1 to the DBCursor set, set_both, set_range and set_recno methods.

The default of returning None makes it easy to do things like this without having to catch DBNotFoundError (KeyError):

data = mydb.get(key)
if data:
    doSomething(data)

or this:

rec = cursor.first()
while rec:
    print rec
    rec = cursor.next()

Making the cursor set methods return None is useful in order to do this:

rec = mydb.set()
while rec:
    key, val = rec
    doSomething(key, val)
    rec = mydb.next()

The downside to this it that it is inconsistent with the rest of the package and noticeably diverges from the Oracle Berkeley DB API. If you prefer to have the get and set methods raise an exception when a key is not found, use this method to tell them to do so.

Calling this method on a DBEnv object will set the default for all DB’s later created within that environment. Calling it on a DB object sets the behaviour for that DB only.

The previous setting is returned.

set_private(object)¶: Link an object to the DBEnv object. This allows to pass around an arbitrary object. For instance, for callback context.

get_private()¶: Give the object linked to the DBEnv.

get_open_flags()¶: Returns the current open method flags. That is, this method returns the flags that were specified when DB_ENV->open() was called. More info…

get_lg_filemode()¶: Returns the log file mode. More info…

set_lg_filemode(filemode)¶: Set the absolute file mode for created log files. More info…

get_lg_bsize()¶: Returns the size of the log buffer, in bytes. More info…

set_lg_bsize(size)¶: Set the size of the in-memory log buffer, in bytes. More info…

get_lg_dir()¶: Returns the log directory, which is the location for logging files. More info…

set_lg_dir(dir)¶: The path of a directory to be used as the location of logging files. Log files created by the Log Manager subsystem will be created in this directory. More info…

set_lg_max(size)¶: Set the maximum size of a single file in the log, in bytes. More info…

get_lg_max(size)¶: Returns the maximum log file size. More info…

get_lg_regionmax()¶: Returns the size of the underlying logging subsystem region. More info…

set_lg_regionmax(size)¶: Set the maximum size of a single region in the log, in bytes. More info…

get_lk_partitions()¶: Returns the number of lock table partitions used in the Berkeley DB environment. More info…

set_lk_partitions(partitions)¶: Set the number of lock table partitions in the Berkeley DB environment. More info…

get_lk_detect()¶: Returns the deadlock detector configuration. More info…

set_lk_detect(mode)¶: Set the automatic deadlock detection mode. More info…

set_lk_max(max)¶: Set the maximum number of locks. (This method is deprecated.) More info…

get_lk_max_locks()¶: Returns the maximum number of potential locks. More info…

set_lk_max_locks(max)¶: Set the maximum number of locks supported by the Berkeley DB lock subsystem. More info…

get_lk_max_lockers()¶: Returns the maximum number of potential lockers. More info…

set_lk_max_lockers(max)¶: Set the maximum number of simultaneous locking entities supported by the Berkeley DB lock subsystem. More info…

get_lk_max_objects()¶: Returns the maximum number of locked objects. More info…

set_lk_max_objects(max)¶: Set the maximum number of simultaneously locked objects supported by the Berkeley DB lock subsystem. More info…

get_mp_mmapsize()¶: Returns the the maximum file size, in bytes, for a file to be mapped into the process address space. More info…

set_mp_mmapsize(size)¶

Files that are opened read-only in the memory pool (and that satisfy a few other criteria) are, by default, mapped into the process address space instead of being copied into the local cache. This can result in better-than-usual performance, as available virtual memory is normally much larger than the local cache, and page faults are faster than page copying on many systems. However, in the presence of limited virtual memory it can cause resource starvation, and in the presence of large databases, it can result in immense process sizes.

This method sets the maximum file size, in bytes, for a file to be mapped into the process address space. If no value is specified, it defaults to 10MB. More info…

stat_print(flags=0)¶: Displays the default subsystem statistical information. More info…

log_file(lsn)¶: Maps lsn to filenames, returning the name of the file containing the named record. More info…

log_printf(string, txn=None)¶: Appends an informational message to the Berkeley DB database environment log files. More info…

log_archive(flags=0)¶: Returns a list of log or database file names. By default, log_archive returns the names of all of the log files that are no longer in use (e.g., no longer involved in active transactions), and that may safely be archived for catastrophic recovery and then removed from the system. More info…

log_flush()¶: Force log records to disk. Useful if the environment, database or transactions are used as ACI, instead of ACID. For example, if the environment is opened as DB_TXN_NOSYNC. More info…

log_get_config(which)¶: Returns whether the specified which parameter is currently set or not. You can manage this value using the DB_ENV->log_set_config() method. More info…

log_set_config(flags, onoff)¶: Configures the Berkeley DB logging subsystem. More info…

lock_detect(atype, flags=0)¶: Run one iteration of the deadlock detector, returns the number of transactions aborted. More info…

lock_get(locker, obj, lock_mode, flags=0)¶: Acquires a lock and returns a handle to it as a DBLock object. The locker parameter is an integer representing the entity doing the locking, and obj is an object representing the item to be locked. More info…

lock_id()¶: Acquires a locker id, guaranteed to be unique across all threads and processes that have the DBEnv open. More info…

lock_id_free(id)¶: Frees a locker ID allocated by the “dbenv.lock_id()” method. More info…

lock_put(lock)¶: Release the lock. More info…

lock_stat(flags=0)¶

Returns a dictionary of locking subsystem statistics with the following keys:

id Last allocated lock ID.

cur_maxid The current maximum unused locker ID.

nmodes Number of lock modes.

maxlocks Maximum number of locks possible.

maxlockers Maximum number of lockers possible.

maxobjects Maximum number of objects possible.

nlocks Number of current locks.

maxnlocks Maximum number of locks at once.

nlockers Number of current lockers.

nobjects Number of current lock objects.

maxnobjects Maximum number of lock objects at once.

maxnlockers Maximum number of lockers at once.

nrequests Total number of locks requested.

nreleases Total number of locks released.

nupgrade Total number of locks upgraded.

ndowngrade Total number of locks downgraded.

lock_wait The number of lock requests not immediately available due to conflicts, for which the thread of control waited.

lock_nowait The number of lock requests not immediately available due to conflicts, for which the thread of control did not wait.

ndeadlocks Number of deadlocks.

locktimeout Lock timeout value.

nlocktimeouts The number of lock requests that have timed out.

txntimeout Transaction timeout value.

ntxntimeouts The number of transactions that have timed out. This value is also a component of ndeadlocks, the total number of deadlocks detected.

objs_wait The number of requests to allocate or deallocate an object for which the thread of control waited.

objs_nowait The number of requests to allocate or deallocate an object for which the thread of control did not wait.

lockers_wait The number of requests to allocate or deallocate a locker for which the thread of control waited.

lockers_nowait The number of requests to allocate or deallocate a locker for which the thread of control did not wait.

locks_wait The number of requests to allocate or deallocate a lock structure for which the thread of control waited.

locks_nowait The number of requests to allocate or deallocate a lock structure for which the thread of control did not wait.

hash_len Maximum length of a lock hash bucket.

regsize Size of the region.

region_wait Number of times a thread of control was forced to wait before obtaining the region lock.

region_nowait Number of times a thread of control was able to obtain the region lock without waiting.

More info…

lock_stat_print(flags=0)¶: Displays the locking subsystem statistical information. More info…

get_tx_max()¶: Returns the number of active transactions. More info…

set_tx_max(max)¶: Set the maximum number of active transactions. More info…

get_tx_timestamp()¶: Returns the recovery timestamp. More info…

set_tx_timestamp(timestamp)¶: Recover to the time specified by timestamp rather than to the most current possible date. More info…

txn_begin(parent=None, flags=0)¶: Creates and begins a new transaction. A DBTxn object is returned. More info…

txn_checkpoint(kbyte=0, min=0, flag=0)¶: Flushes the underlying memory pool, writes a checkpoint record to the log and then flushes the log. More info…

txn_stat(flags=0)¶

Return a dictionary of transaction statistics with the following keys:

last_ckp The LSN of the last checkpoint.

time_ckp Time the last completed checkpoint finished (as the number of seconds since the Epoch, returned by the IEEE/ANSI Std 1003.1 POSIX time interface).

last_txnid Last transaction ID allocated.

maxtxns Max number of active transactions possible.

nactive Number of transactions currently active.

maxnactive Max number of active transactions at once.

nsnapshot The number of transactions on the snapshot list. These are transactions which modified a database opened with DB_MULTIVERSION, and which have committed or aborted, but the copies of pages they created are still in the cache.

maxnsnapshot The maximum number of transactions on the snapshot list at any one time.

nbegins Number of transactions that have begun.

naborts Number of transactions that have aborted.

ncommits Number of transactions that have committed.

nrestores Number of transactions that have been restored.

regsize Size of the region.

region_wait Number of times that a thread of control was forced to wait before obtaining the region lock.

region_nowait Number of times that a thread of control was able to obtain the region lock without waiting.

More info…

txn_stat_print(flags=0)¶: Displays the transaction subsystem statistical information. More info…

lsn_reset(file=None, flags=0)¶: This method allows database files to be moved from one transactional database environment to another. More info…

log_stat(flags=0)¶

Returns a dictionary of logging subsystem statistics with the following keys:

magic The magic number that identifies a file as a log file.

version The version of the log file type.

mode The mode of any created log files.

lg_bsize The in-memory log record cache size.

lg_size The log file size.

record The number of records written to this log.

w_mbytes The number of megabytes written to this log.

w_bytes The number of bytes over and above w_mbytes written to this log.

wc_mbytes The number of megabytes written to this log since the last checkpoint.

wc_bytes The number of bytes over and above wc_mbytes written to this log since the last checkpoint.

wcount The number of times the log has been written to disk.

wcount_fill The number of times the log has been written to disk because the in-memory log record cache filled up.

rcount The number of times the log has been read from disk.

scount The number of times the log has been flushed to disk.

cur_file The current log file number.

cur_offset The byte offset in the current log file.

disk_file The log file number of the last record known to be on disk.

disk_offset The byte offset of the last record known to be on disk.

maxcommitperflush The maximum number of commits contained in a single log flush.

mincommitperflush The minimum number of commits contained in a single log flush that contained a commit.

regsize The size of the log region, in bytes.

region_wait The number of times that a thread of control was forced to wait before obtaining the log region mutex.

region_nowait The number of times that a thread of control was able to obtain the log region mutex without waiting.

More info…

log_stat_print(flags=0)¶: Displays the logging subsystem statistical information. More info…

txn_recover()¶

Returns a list of tuples (GID, TXN) of transactions prepared but still unresolved. This is used while doing environment recovery in an application using distributed transactions.

This method must be called only from a single thread at a time. It should be called after DBEnv recovery. More info…

set_verbose(which, onoff)¶: Turns specific additional informational and debugging messages in the Berkeley DB message output on and off. To see the additional messages, verbose messages must also be configured for the application. More info…

get_verbose(which)¶: Returns whether the specified which parameter is currently set or not. More info…

set_event_notify(eventFunc)¶: Configures a callback function which is called to notify the process of specific Berkeley DB events. More info…

mutex_stat(flags=0)¶

Returns a dictionary of mutex subsystem statistics with the following keys:

mutex_align The mutex alignment, in bytes.

mutex_tas_spins The number of times test-and-set mutexes will spin without blocking.

mutex_cnt The total number of mutexes configured.

mutex_free The number of mutexes currently available.

mutex_inuse The number of mutexes currently in use.

mutex_inuse_max The maximum number of mutexes ever in use.

regsize The size of the mutex region, in bytes.

region_wait The number of times that a thread of control was forced to wait before obtaining the mutex region mutex.

region_nowait The number of times that a thread of control was able to obtain the mutex region mutex without waiting.

More info…

mutex_stat_print(flags=0)¶: Displays the mutex subsystem statistical information. More info…

mutex_set_max(value)¶: Configure the total number of mutexes to allocate. More info…

mutex_get_max()¶: Returns the total number of mutexes allocated. More info…

mutex_set_increment(value)¶: Configure the number of additional mutexes to allocate. More info…

mutex_get_increment()¶: Returns the number of additional mutexes to allocate. More info…

mutex_set_align(align)¶: Set the mutex alignment, in bytes. More info…

mutex_get_align()¶: Returns the mutex alignment, in bytes. More info…

mutex_set_tas_spins(tas_spins)¶: Specify that test-and-set mutexes should spin tas_spins times without blocking. Check the default values in the Oracle webpage. More info…

mutex_get_tas_spins()¶: Returns the test-and-set spin count. More info…

DBEnv Replication Manager Methods¶

This module automates many of the tasks needed to provide replication abilities in a Berkeley DB system. The module is fairly limited, but enough in many cases. Users more demanding must use the full Base Replication API.

This module requires pthread support (in Unix), so you must compile Berkeley DB with it if you want to be able to use the Replication Manager.

repmgr_start(nthreads, flags)¶: Starts the replication manager. More info…

repmgr_site(host, port)¶: Returns a DB_SITE handle that defines a site’s host/port network address. You use the DB_SITE handle to configure and manage replication sites. More info…

repmgr_site_by_eid(eid)¶: Returns a DB_SITE handle based on the site’s Environment ID value. You use the DB_SITE handle to configure and manage replication sites. More info…

repmgr_set_ack_policy(ack_policy)¶: Specifies how master and client sites will handle acknowledgment of replication messages which are necessary for “permanent” records. More info…

repmgr_get_ack_policy()¶: Returns the replication manager’s client acknowledgment policy. More info…

repmgr_site_list()¶

Returns a dictionary with the status of the sites currently known by the replication manager.

The keys are the Environment ID assigned by the replication manager. This is the same value that is passed to the application’s event notification function for the DB_EVENT_REP_NEWMASTER event.

The values are tuples containing the hostname, the TCP/IP port number and the link status.

More info…

repmgr_stat(flags=0)¶

Returns a dictionary with the replication manager statistics. Keys are:

perm_failed	The number of times a message critical for maintaining database integrity (for example, a transaction commit), originating at this site, did not receive sufficient acknowledgement from clients, according to the configured acknowledgement policy and acknowledgement timeout.
msgs_queued	The number of outgoing messages which could not be transmitted immediately, due to a full network buffer, and had to be queued for later delivery.
msgs_dropped	The number of outgoing messages that were completely dropped, because the outgoing message queue was full. (Berkeley DB replication is tolerant of dropped messages, and will automatically request retransmission of any missing messages as needed.)
connection_drop	The number of times an existing TCP/IP connection failed.
connect_fail	The number of times an attempt to open a new TCP/IP connection failed.

More info…

repmgr_stat_print(flags=0)¶: Displays the replication manager statistical information. More info…

DBEnv Replication Methods¶

This section provides the raw methods for replication. If possible, it is recommended to use the Replication Manager.

rep_elect(nsites, nvotes)¶: Holds an election for the master of a replication group. More info…

rep_set_transport(envid, transportFunc)¶: Initializes the communication infrastructure for a database environment participating in a replicated application. More info…

rep_process_messsage(control, rec, envid)¶

Processes an incoming replication message sent by a member of the replication group to the local database environment.

Returns a two element tuple.

More info…

rep_start(flags, cdata=None)¶

Configures the database environment as a client or master in a group of replicated database environments.

The DB_ENV->rep_start method is not called by most replication applications. It should only be called by applications implementing their own network transport layer, explicitly holding replication group elections and handling replication messages outside of the replication manager framework.

More info…

rep_sync()¶: Forces master synchronization to begin for this client. This method is the other half of setting the DB_REP_CONF_DELAYCLIENT flag via the DB_ENV->rep_set_config method. More info…

rep_set_config(which, onoff)¶: Configures the Berkeley DB replication subsystem. More info…

rep_get_config(which)¶: Returns whether the specified which parameter is currently set or not. More info…

rep_set_limit(bytes)¶: Sets a byte-count limit on the amount of data that will be transmitted from a site in response to a single message processed by the DB_ENV->rep_process_message method. The limit is not a hard limit, and the record that exceeds the limit is the last record to be sent. More info…

rep_get_limit()¶: Gets a byte-count limit on the amount of data that will be transmitted from a site in response to a single message processed by the DB_ENV->rep_process_message method. The limit is not a hard limit, and the record that exceeds the limit is the last record to be sent. More info…

rep_set_request(minimum, maximum)¶: Sets a threshold for the minimum and maximum time that a client waits before requesting retransmission of a missing message. Specifically, if the client detects a gap in the sequence of incoming log records or database pages, Berkeley DB will wait for at least min microseconds before requesting retransmission of the missing record. Berkeley DB will double that amount before requesting the same missing record again, and so on, up to a maximum threshold of max microseconds. More info…

rep_get_request()¶: Returns a tuple with the minimum and maximum number of microseconds a client waits before requesting retransmission. More info…

rep_set_nsites(nsites)¶: Specifies the total number of sites in a replication group. More info…

rep_get_nsites()¶: Returns the total number of sites in the replication group. More info…

rep_set_priority(priority)¶: Specifies the database environment’s priority in replication group elections. The priority must be a positive integer, or 0 if this environment cannot be a replication group master. More info…

rep_get_priority()¶: Returns the database environment priority. More info…

rep_set_timeout(which, timeout)¶: Specifies a variety of replication timeout values. More info…

rep_get_timeout(which)¶: Returns the timeout value for the specified which parameter. More info…

rep_set_clockskew(fast, slow)¶: Sets the clock skew ratio among replication group members based on the fastest and slowest measurements among the group for use with master leases. More info…

rep_get_clockskew()¶: Returns a tuple with the current clock skew values. More info…

rep_stat(flags=0)¶

Returns a dictionary with the replication subsystem statistics. Keys are:

st_bulk_fills	The number of times the bulk buffer filled up, forcing the buffer content to be sent.
bulk_overflows	The number of times a record was bigger than the entire bulk buffer, and therefore had to be sent as a singleton.
bulk_records	The number of records added to a bulk buffer.
bulk_transfers	The number of bulk buffers transferred (via a call to the application’s send function).
client_rerequests	The number of times this client site received a “re-request” message, indicating that a request it previously sent to another client could not be serviced by that client. (Compare to client_svc_miss.)
client_svc_miss	The number of “request” type messages received by this client that could not be processed, forcing the originating requester to try sending the request to the master (or another client).
client_svc_req	The number of “request” type messages received by this client. (“Request” messages are usually sent from a client to the master, but a message marked with the DB_REP_ANYWHERE flag in the invocation of the application’s send function may be sent to another client instead.)
dupmasters	The number of duplicate master conditions originally detected at this site.
egen	The current election generation number.
election_cur_winner	The election winner.
election_gen	The election generation number.
election_lsn	The maximum LSN of election winner.
election_nsites	The number sites responding to this site during the last election.
election_nvotes	The number of votes required in the last election.
election_priority	The election priority.
election_sec	The number of seconds the last election took (the total election time is election_sec plus election_usec).
election_status	The current election phase (0 if no election is in progress).
election_tiebreaker	The election tiebreaker value.
election_usec	The number of microseconds the last election took (the total election time is election_sec plus election_usec).
election_votes	The number of votes received in the last election.
elections	The number of elections held.
elections_won	The number of elections won.
env_id	The current environment ID.
env_priority	The current environment priority.
gen	The current generation number.
log_duplicated	The number of duplicate log records received.
log_queued	The number of log records currently queued.
log_queued_max	The maximum number of log records ever queued at once.
log_queued_total	The total number of log records queued.
log_records	The number of log records received and appended to the log.
log_requested	The number of times log records were missed and requested.
master	The current master environment ID.
master_changes	The number of times the master has changed.
max_lease_sec	The number of seconds of the longest lease (the total lease time is max_lease_sec plus max_lease_usec).
max_lease_usec	The number of microseconds of the longest lease (the total lease time is max_lease_sec plus max_lease_usec).
max_perm_lsn	The LSN of the maximum permanent log record, or 0 if there are no permanent log records.
msgs_badgen	The number of messages received with a bad generation number.
msgs_processed	The number of messages received and processed.
msgs_recover	The number of messages ignored due to pending recovery.
msgs_send_failures	The number of failed message sends.
msgs_sent	The number of messages sent.
newsites	The number of new site messages received.
next_lsn	In replication environments configured as masters, the next LSN expected. In replication environments configured as clients, the next LSN to be used.
next_pg	The next page number we expect to receive.
nsites	The number of sites used in the last election.
nthrottles	Transmission limited. This indicates the number of times that data transmission was stopped to limit the amount of data sent in response to a single call to DB_ENV->rep_process_message.
outdated	The number of outdated conditions detected.
pg_duplicated	The number of duplicate pages received.
pg_records	The number of pages received and stored.
pg_requested	The number of pages missed and requested from the master.
startsync_delayed	The number of times the client had to delay the start of a cache flush operation (initiated by the master for an impending checkpoint) because it was missing some previous log record(s).
startup_complete	The client site has completed its startup procedures and is now handling live records from the master.
status	The current replication mode. Set to DB_REP_MASTER if the environment is a replication master, DB_REP_CLIENT if the environment is a replication client, or 0 if replication is not configured.
txns_applied	The number of transactions applied.
waiting_lsn	The LSN of the first log record we have after missing log records being waited for, or 0 if no log records are currently missing.
waiting_pg	The page number of the first page we have after missing pages being waited for, or 0 if no pages are currently missing.

More info…

rep_stat_print(flags=0)¶: Displays the replication subsystem statistical information. More info…

DBEnv¶

DBEnv Attributes¶

DBEnv Methods¶

DBEnv Replication Manager Methods¶

DBEnv Replication Methods¶

Table Of Contents

Related Topics

gbytes	Gigabytes of cache (total cache size is st_gbytes + st_bytes).
bytes	Bytes of cache (total cache size is st_gbytes + st_bytes).
ncache	Number of caches.
max_ncache	Maximum number of caches, as configured with the DB_ENV->set_cache_max() method.
regsize	Individual cache size, in bytes.
mmapsize	Maximum memory-mapped file size.
maxopenfd	Maximum open file descriptors.
maxwrite	Maximum sequential buffer writes.
maxwrite_sleep	Microseconds to pause after writing maximum sequential buffers.
map	Requested pages mapped into the process’ address space (there is no available information about whether or not this request caused disk I/O, although examining the application page fault rate may be helpful).
cache_hit	Requested pages found in the cache.
cache_miss	Requested pages not found in the cache.
page_create	Pages created in the cache.
page_in	Pages read into the cache.
page_out	Pages written from the cache to the backing file.
ro_evict	Clean pages forced from the cache.
rw_evict	Dirty pages forced from the cache.
page_trickle	Dirty pages written using the DB_ENV->memp_trickle() method.
pages	Pages in the cache.
page_clean	Clean pages currently in the cache.
page_dirty	Dirty pages currently in the cache.
hash_buckets	Number of hash buckets in buffer hash table.
hash_searches	Total number of buffer hash table lookups.
hash_longest	Longest chain ever encountered in buffer hash table lookups.
hash_examined	Total number of hash elements traversed during hash table lookups.
hash_nowait	Number of times that a thread of control was able to obtain a hash bucket lock without waiting.
hash_wait	Number of times that a thread of control was forced to wait before obtaining a hash bucket lock.
hash_max_nowait	The number of times a thread of control was able to obtain the hash bucket lock without waiting on the bucket which had the maximum number of times that a thread of control needed to wait.
hash_max_wait	Maximum number of times any hash bucket lock was waited for by a thread of control.
region_wait	Number of times that a thread of control was forced to wait before obtaining a cache region mutex.
region_nowait	Number of times that a thread of control was able to obtain a cache region mutex without waiting.
mvcc_frozen	Number of buffers frozen.
mvcc_thawed	Number of buffers thawed.
mvcc_freed	Number of frozen buffers freed.
alloc	Number of page allocations.
alloc_buckets	Number of hash buckets checked during allocation.
alloc_max_buckets	Maximum number of hash buckets checked during an allocation.
alloc_pages	Number of pages checked during allocation.
alloc_max_pages	Maximum number of pages checked during an allocation.
io_wait	Number of operations blocked waiting for I/O to complete.
sync_interrupted	Number of mpool sync operations interrupted.

pagesize	Page size in bytes.
cache_hit	Requested pages found in the cache.
cache_miss	Requested pages not found in the cache.
map	Requested pages mapped into the process’ address space.
page_create	Pages created in the cache.
page_in	Pages read into the cache.
page_out	Pages written from the cache to the backing file.

id	Last allocated lock ID.
cur_maxid	The current maximum unused locker ID.
nmodes	Number of lock modes.
maxlocks	Maximum number of locks possible.
maxlockers	Maximum number of lockers possible.
maxobjects	Maximum number of objects possible.
nlocks	Number of current locks.
maxnlocks	Maximum number of locks at once.
nlockers	Number of current lockers.
nobjects	Number of current lock objects.
maxnobjects	Maximum number of lock objects at once.
maxnlockers	Maximum number of lockers at once.
nrequests	Total number of locks requested.
nreleases	Total number of locks released.
nupgrade	Total number of locks upgraded.
ndowngrade	Total number of locks downgraded.
lock_wait	The number of lock requests not immediately available due to conflicts, for which the thread of control waited.
lock_nowait	The number of lock requests not immediately available due to conflicts, for which the thread of control did not wait.
ndeadlocks	Number of deadlocks.
locktimeout	Lock timeout value.
nlocktimeouts	The number of lock requests that have timed out.
txntimeout	Transaction timeout value.
ntxntimeouts	The number of transactions that have timed out. This value is also a component of ndeadlocks, the total number of deadlocks detected.
objs_wait	The number of requests to allocate or deallocate an object for which the thread of control waited.
objs_nowait	The number of requests to allocate or deallocate an object for which the thread of control did not wait.
lockers_wait	The number of requests to allocate or deallocate a locker for which the thread of control waited.
lockers_nowait	The number of requests to allocate or deallocate a locker for which the thread of control did not wait.
locks_wait	The number of requests to allocate or deallocate a lock structure for which the thread of control waited.
locks_nowait	The number of requests to allocate or deallocate a lock structure for which the thread of control did not wait.
hash_len	Maximum length of a lock hash bucket.
regsize	Size of the region.
region_wait	Number of times a thread of control was forced to wait before obtaining the region lock.
region_nowait	Number of times a thread of control was able to obtain the region lock without waiting.

last_ckp	The LSN of the last checkpoint.
time_ckp	Time the last completed checkpoint finished (as the number of seconds since the Epoch, returned by the IEEE/ANSI Std 1003.1 POSIX time interface).
last_txnid	Last transaction ID allocated.
maxtxns	Max number of active transactions possible.
nactive	Number of transactions currently active.
maxnactive	Max number of active transactions at once.
nsnapshot	The number of transactions on the snapshot list. These are transactions which modified a database opened with DB_MULTIVERSION, and which have committed or aborted, but the copies of pages they created are still in the cache.
maxnsnapshot	The maximum number of transactions on the snapshot list at any one time.
nbegins	Number of transactions that have begun.
naborts	Number of transactions that have aborted.
ncommits	Number of transactions that have committed.
nrestores	Number of transactions that have been restored.
regsize	Size of the region.
region_wait	Number of times that a thread of control was forced to wait before obtaining the region lock.
region_nowait	Number of times that a thread of control was able to obtain the region lock without waiting.

magic	The magic number that identifies a file as a log file.
version	The version of the log file type.
mode	The mode of any created log files.
lg_bsize	The in-memory log record cache size.
lg_size	The log file size.
record	The number of records written to this log.
w_mbytes	The number of megabytes written to this log.
w_bytes	The number of bytes over and above w_mbytes written to this log.
wc_mbytes	The number of megabytes written to this log since the last checkpoint.
wc_bytes	The number of bytes over and above wc_mbytes written to this log since the last checkpoint.
wcount	The number of times the log has been written to disk.
wcount_fill	The number of times the log has been written to disk because the in-memory log record cache filled up.
rcount	The number of times the log has been read from disk.
scount	The number of times the log has been flushed to disk.
cur_file	The current log file number.
cur_offset	The byte offset in the current log file.
disk_file	The log file number of the last record known to be on disk.
disk_offset	The byte offset of the last record known to be on disk.
maxcommitperflush	The maximum number of commits contained in a single log flush.
mincommitperflush	The minimum number of commits contained in a single log flush that contained a commit.
regsize	The size of the log region, in bytes.
region_wait	The number of times that a thread of control was forced to wait before obtaining the log region mutex.
region_nowait	The number of times that a thread of control was able to obtain the log region mutex without waiting.

mutex_align	The mutex alignment, in bytes.
mutex_tas_spins	The number of times test-and-set mutexes will spin without blocking.
mutex_cnt	The total number of mutexes configured.
mutex_free	The number of mutexes currently available.
mutex_inuse	The number of mutexes currently in use.
mutex_inuse_max	The maximum number of mutexes ever in use.
regsize	The size of the mutex region, in bytes.
region_wait	The number of times that a thread of control was forced to wait before obtaining the mutex region mutex.
region_nowait	The number of times that a thread of control was able to obtain the mutex region mutex without waiting.