class BDB::Env
Berkeley DB environment is an encapsulation of one or more databases, log files and shared information about the database environment such as shared memory buffer cache pages.
The simplest way to administer a Berkeley DB application environment is to create a single home directory that stores the files for the applications that will share the environment. The environment home directory must be created before any Berkeley DB applications are run. Berkeley DB itself never creates the environment home directory. The environment can then be identified by the name of that directory.
Public Class Methods
same than open
# File env.rb, line 137 def create(home, flags = 0, mode = 0, options = {}) end
same than open
# File env.rb, line 140 def new(home, flags = 0, mode = 0, options = {}) end
open the Berkeley DB environment
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home If this argument is non-NULL, its value may be used as the database home, and files named relative to its path.
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mode mode for creation (see chmod(2))
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flags must be set to 0 or by OR'ing with
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BDB::INIT_CDB Initialize locking.
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BDB::INIT_LOCK Initialize the locking subsystem.
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BDB::INIT_LOG Initialize the logging subsystem.
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BDB::INIT_MPOOL Initialize the shared memory buffer pool subsystem.
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BDB::INIT_TXN Initialize the transaction subsystem.
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BDB::INIT_TRANSACTION Equivalent to DB_INIT_LOCK|DB_INIT_MPOOL|DB_INIT_TXN|DB_INIT_LOG
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BDB::RECOVER Run normal recovery on this environment before opening it for normal use. If this flag is set, the DB_CREATE flag must also be set since the regions will be removed and recreated.
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BDB::RECOVER_FATAL Run catastrophic recovery on this environment before opening it for normal use. If this flag is set, the DB_CREATE flag must also be set since the regions will be removed and recreated.
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BDB::USE_ENVIRON The Berkeley DB process' environment may be permitted to specify information to be used when naming files
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BDB::USE_ENVIRON_ROOT The Berkeley DB process' environment may be permitted to specify information to be used when naming files; if the DB_USE_ENVIRON_ROOT flag is set, environment information will be used for file naming only for users with appropriate permissions
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BDB::CREATE Cause Berkeley DB subsystems to create any underlying files, as necessary.
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BDB::LOCKDOWN Lock shared Berkeley DB environment files and memory mapped databases into memory.
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BDB::NOMMAP Always copy read-only database files in this environment into the local cache instead of potentially mapping them into process memory
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BDB::PRIVATE Specify that the environment will only be accessed by a single process
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BDB::SYSTEM_MEM Allocate memory from system shared memory instead of from memory backed by the filesystem.
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BDB::TXN_NOSYNC Do not synchronously flush the log on transaction commit or prepare. This means that transactions exhibit the ACI (atomicity, consistency and isolation) properties, but not D (durability), i.e., database integrity will be maintained but it is possible that some number of the most recently committed transactions may be undone during recovery instead of being redone.
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BDB::CDB_ALLDB For Berkeley DB Concurrent Data Store applications, perform locking on an environment-wide basis rather than per-database.
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options Hash, Possible options are (see the documentation of Berkeley DB for more informations)
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set_app_dispatch : configure application recovery interface (DB >= 4.1)
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set_cachesize : set the database cache size
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set_data_dir : set the environment data directory (DB >= 3)
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set_encrypt : set the environment cryptographic key (DB >= 4.1)
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set_feedback : set feedback callback (DB >= 3)
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set_flags : environment configuration (DB >= 3.2)
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set_lg_bsize : set log buffer size (DB >= 3)
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set_lg_dir : set the environment logging directory (DB >= 3)
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set_lg_max : set log file size
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set_lg_regionmax : set logging region size (DB >= 3)
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set_lk_conflicts : set lock conflicts matrix (DB >= 3)
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set_lk_detect : set automatic deadlock detection
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set_lk_max_lockers : set maximum number of lockers
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set_lk_max_locks : set maximum number of locks
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set_lk_max_objects : set maximum number of lock objects
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set_rep_transport : configure replication transport (DB >= 4)
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set_rep_limit : limit data sent in response to a single message (DB >= 4.1)
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set_rep_nsites : configure replication group site count (DB >= 4.5)
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set_rep_priority : configure replication site priority (DB >= 4.5)
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set_rep_config : configure the replication subsystem (DB >= 4.5)
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set_rep_timeout : configure replication timeouts (DB >= 4.5)
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set_rpc_server : establish an RPC server connection (DB >= 3.1)
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set_tas_spins : set the number of test-and-set spins (DB >= 3)
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set_tmp_dir : set the environment temporary file directory (DB >= 3)
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set_timeout : set lock and transaction timeout (DB >= 4)
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set_tx_max : set maximum number of transactions (DB >= 3)
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set_tx_timestamp : set recovery timestamp (DB >= 3.1)
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set_verbose : set verbose messages
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set_verb_chkpoint :display checkpoint location information when searching the log for checkpoints. (DB >= 3)
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set_verb_deadlock : display additional information when doing deadlock detection. (DB >= 3)
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set_verb_recovery : display additional information when performing recovery. (DB >= 3)
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set_verb_replication : display additional information when processing replication messages. (DB >= 4)
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set_verb_waitsfor : display the waits-for table when doing deadlock detection. (DB >= 3)
Proc given to set_feedback, set_app_dispatch and set_rep_transport can be also specified as a method (replace the prefix set_ with bdb_)
For bdb_rep_transport the constant ENVID must be defined
The constant BDB::ENCRYPT can be used to replace set_encrypt
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# File env.rb, line 134 def open(home, flags = 0, mode = 0, options = {}) end
remove the environnement
# File env.rb, line 145 def remove() end
same than remove
# File env.rb, line 148 def unlink() end
Public Instance Methods
begin a transaction (the transaction manager must be enabled). flags can have the value DBD::TXN_COMMIT, in this case the transaction will be commited at end.
# File env.rb, line 325 def begin(flags = 0) end
The txn_checkpoint
function flushes the underlying memory pool, writes a checkpoint record to the log and then flushes the log.
If either kbyte or min is non-zero, the checkpoint is only done if more than min minutes have passed since the last checkpoint, or if more than kbyte kilobytes of log data have been written since the last checkpoint.
# File env.rb, line 339 def checkpoint(kbyte, min = 0) end
close the environnement
# File env.rb, line 154 def close() end
only with BDB::VERSION_MAJOR == 4 && BDB::VERSION_MINOR >= 1
remove the database specified by file and database. If no database is nil, the underlying file represented by file is removed, incidentally removing all databases that it contained.
The flags value must be set to 0 or BDB::AUTO_COMMIT
# File env.rb, line 166 def dbremove(file, database = nil, flags = 0) end
only with BDB::VERSION_MAJOR == 4 && BDB::VERSION_MINOR >= 1
rename the database specified by file and database to newname. If database is nil, the underlying file represented by file is renamed, incidentally renaming all databases that it contained.
The flags value must be set to 0 or BDB::AUTO_COMMIT
# File env.rb, line 178 def dbrename(file, database, newname, flags = 0) end
Only for DB >= 4
Holds an election for the master of a replication group, returning the new master's ID
Raise BDB::RepUnavail if the timeout expires
# File env.rb, line 361 def elect(sites, priority, timeout) end
Only for DB >= 4.4
The method checks for threads of control (either a true thread or a process) that have exited while manipulating Berkeley DB library data structures
flag is actually unused and must be set to 0
# File env.rb, line 467 def failcheck(flag = 0) end
monitor the progress of some operations
# File env.rb, line 183 def feedback=(proc) end
Only for DB >= 4.4
Reset database file ID
The Env#fileid_reset
method allows database files to be copied, and then the copy used in the same database environment as the original.
fileThe name of the physical file in which new file IDs are to be created. flags must be set to 0 or BDB::ENCRYPT
# File env.rb, line 413 def fileid_reset(file, flags = 0) end
return the name of the directory
# File env.rb, line 188 def home() end
Only for DB >= 4.4
Declare a proc that returns if a thread of control (either a true thread or a process) is still running.
The proc will be called with 2 arguments (pid, tid)
# File env.rb, line 456 def is_alive=(call_proc) end
Acquire a locker ID
# File env.rb, line 193 def lock() end
The lock_detect
function runs one iteration of the deadlock detector. The deadlock detector traverses the lock table, and for each deadlock it finds, marks one of the participating transactions for abort.
type can have one the value BDB::LOCK_OLDEST, BDB::LOCK_RANDOM or BDB::LOCK_YOUNGUEST
flags can have the value BDB::LOCK_CONFLICT, in this case the deadlock detector is run only if a lock conflict has occurred since the last time that the deadlock detector was run.
return the number of transactions aborted by the lock_detect
function if BDB::VERSION_MAJOR >= 3 or zero
# File env.rb, line 214 def lock_detect(type, flags = 0) end
same than lock
# File env.rb, line 196 def lock_id() end
Return lock subsystem statistics
# File env.rb, line 220 def lock_stat() end
The log_archive
function return an array of log or database file names.
flags value must be set to 0 or the value BDB::ARCH_DATA, BDB::ARCH_ABS, BDB::ARCH_LOG
# File env.rb, line 228 def log_archive(flags = 0) end
same as log_put(string, BDB::CHECKPOINT)
# File env.rb, line 234 def log_checkpoint(string) end
same as log_put(string, BDB::CURLSN)
# File env.rb, line 240 def log_curlsn(string) end
Implement an iterator inside of the log
# File env.rb, line 246 def log_each yield string, lsn end
same as log_put(string, BDB::FLUSH)
Without argument, garantee that all records are written to the disk
# File env.rb, line 255 def log_flush(string = nil) end
The log_get return an array [String, BDB::Lsn] according to the flag value.
flag can has the value BDB::CHECKPOINT, BDB::FIRST, BDB::LAST, BDB::NEXT, BDB::PREV, BDB::CURRENT
# File env.rb, line 265 def log_get(flag) end
The log_put function appends records to the log. It return an object BDB::Lsn
flag can have the value BDB::CHECKPOINT, BDB::CURLSN, BDB::FLUSH
# File env.rb, line 275 def log_put(string, flag = 0) end
Implement an iterator inside of the log
# File env.rb, line 281 def log_reverse_each yield string, lsn end
return log statistics
# File env.rb, line 288 def log_stat end
Only for DB >= 4.4
Reset database file LSN
The Env#lsn_reset
method allows database files to be moved from one transactional database environment to another.
fileThe name of the physical file in which the LSNs are to be cleared. flags must be set to 0 or BDB::ENCRYPT
# File env.rb, line 400 def lsn_reset(file, flags = 0) end
Only for DB >= 4.4
There are interfaces in the Berkeley DB library which either directly output informational messages or statistical information : Env#msgcall is used to set callback which will called by BDB
The value given must be nil to unconfigure the callback, or and object which respond to #call : it will called with a String as argument
# File env.rb, line 425 def msgcall=(call_proc) end
open the database in the current environment. type must be one of the constant BDB::BTREE, BDB::HASH, BDB::RECNO, BDB::QUEUE. See open for other arguments
# File env.rb, line 296 def open_db(type, name = nil, subname = nil, flags = 0, mode = 0) end
Only for DB >= 4
Processes an incoming replication message sent by a member of the replication group to the local database environment
# File env.rb, line 372 def process_message(control, rec, envid) end
only with BDB::VERSION_MAJOR == 3 && BDB::VERSION_MINOR >= 3
iterate over all prepared transactions. The transaction txn must be made a call to abort, commit, discard
id is the global transaction ID for the transaction
# File env.rb, line 306 def recover yield txn, id end
Only for DB >= 4.5
Configures the Berkeley DB replication subsystem.
which can have the value BDB::REP_CONF_BULK, BDB::REP_CONF_DELAYCLIENT, BDB::REP_CONF_NOAUTOINIT, BDB::REP_CONF_NOWAIT
onoff can have the value true or false
# File env.rb, line 524 def rep_config[]=(which, onoff) end
Only for DB >= 4.5
Returns true if the specified which parameter is currently set or not.
# File env.rb, line 530 def rep_config?[](which) end
same than elect
# File env.rb, line 364 def rep_elect(sites, priority, timeout) end
Only for DB >= 4.5
Returns the total number of sites in a replication group.
# File env.rb, line 542 def rep_nsites end
Only for DB >= 4.5
Specifies the total number of sites in a replication group.
# File env.rb, line 536 def rep_nsites=(sites) end
Only for DB >= 4.5
Returns the database environment priority.
# File env.rb, line 554 def rep_priority end
Only for DB >= 4.5
Specifies the priority in the replication group elections.
# File env.rb, line 548 def rep_priority=(priority) end
same than process_message
# File env.rb, line 375 def rep_process_message(control, rec, envid) end
same than start
# File env.rb, line 387 def rep_start(cdata, flags) end
Only for DB >= 4.5
Specifies the timeout in the replication group elections.
which can have the value BDB::REP_ACK_TIMEOUT, BDB::REP_ELECTION_TIMEOUT, BDB::REP_ELECTION_RETRY, BDB::REP_CONNECTION_RETRY
# File env.rb, line 564 def rep_timeout[]=(which, timeout) end
Only for DB >= 4.5
Returns the replication manager's client acknowledgment policy.
# File env.rb, line 493 def repmgr_ack_policy end
Only for DB >= 4.5
Specifies how master and client sites will handle acknowledgment of replication messages which are necessary for “permanent” records.
policy must be set to one of the following values BDB::REPMGR_ACKS_ALL, BDB::REPMGR_ACKS_ALL_PEERS, BDB::REPMGR_ACKS_NONE, BDB::REPMGR_ACKS_ONE, BDB::REPMGR_ACKS_ONE_PEER, BDB::REPMGR_ACKS_QUORUM
# File env.rb, line 487 def repmgr_ack_policy=(policy) end
Only for DB >= 4.5
Adds a new replication site to the replication manager's list of known sites.
Return the environment ID assigned to the remote site
# File env.rb, line 475 def repmgr_add_remote(host, port, flag = 0) end
Only for DB >= 4.5
Specifies the host identification string and port number for the local system.
# File env.rb, line 506 def repmgr_set_local_site(host, port, flag = 0) end
Only for DB >= 4.5
Returns an array with the status of the sites currently known by the replication manager.
# File env.rb, line 500 def repmgr_site_list end
Only for DB >= 4.5
Starts the replication manager.
# File env.rb, line 512 def repmgr_start(count, flag) end
only with BDB::VERSION_MAJOR == 3 && BDB::VERSION_MINOR >= 2
flags can have the value BDB::CDB_ALLDB, BDB::NOMMAP BDB::TXN_NOSYNC
if onoff is false, the specified flags are cleared
# File env.rb, line 318 def set_flags(flags, onoff = true) end
Only for DB >= 4
cdata is an identifier flags must be one of BDB::REP_CLIENT, BDB::REP_MASTER or BDB::REP_LOGSONLY
# File env.rb, line 384 def start(cdata, flags) end
Return transaction subsystem statistics
# File env.rb, line 348 def stat() end
Only for DB >= 4.4
Declare a proc object which returns a unique identifier pair for the current thread of control.
The proc must return a pair
*<em>pid</em>: process ID of the current thread *<em>tid</em>: thread ID of the current thread
# File env.rb, line 437 def thread_id=(call_proc) end
Only for DB >= 4.4
Declare a proc that formats a process ID and thread ID identifier pair for display.
The proc will be called with 2 arguments and must return a String
# File env.rb, line 446 def thread_id_string=(call_proc) end
same than begin
# File env.rb, line 328 def txn_begin(flags = 0) end
same than checkpoint
# File env.rb, line 342 def txn_checkpoint(kbyte, min = 0) end
same than stat
# File env.rb, line 351 def txn_stat() end