зеркало из https://github.com/mozilla/gecko-dev.git
1063 строки
25 KiB
Groff
1063 строки
25 KiB
Groff
.ds TYPE C
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.\"
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.\" See the file LICENSE for redistribution information.
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.\"
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.\" Copyright (c) 1996, 1997, 1998
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.\" Sleepycat Software. All rights reserved.
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.\"
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.\" @(#)db_archive.so 10.11 (Sleepycat) 5/3/98
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.\"
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.\"
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.\" See the file LICENSE for redistribution information.
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.\"
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.\" Copyright (c) 1997, 1998
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.\" Sleepycat Software. All rights reserved.
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.\"
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.\" @(#)macros.so 10.45 (Sleepycat) 5/4/98
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.\"
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.\" We don't want hyphenation for any HTML documents.
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.ie '\*[HTML]'YES'\{\
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.nh
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\}
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.el\{\
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.ds Hy
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.hy
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..
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.ds Nh
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.nh
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..
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\}
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.\" The alternative text macro
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.\" This macro takes two arguments:
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.\" + the text produced if this is a "C" manpage
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.\" + the text produced if this is a "CXX" or "JAVA" manpage
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.\"
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.de Al
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.ie '\*[TYPE]'C'\{\\$1
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\}
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.el\{\\$2
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\}
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..
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.\" Scoped name macro.
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.\" Produces a_b, a::b, a.b depending on language
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.\" This macro takes two arguments:
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.\" + the class or prefix (without underscore)
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.\" + the name within the class or following the prefix
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.de Sc
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.ie '\*[TYPE]'C'\{\\$1_\\$2
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\}
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.el\{\
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.ie '\*[TYPE]'CXX'\{\\$1::\\$2
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\}
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.el\{\\$1.\\$2
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\}
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\}
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..
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.\" Scoped name for Java.
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.\" Produces Db.b, for Java, otherwise just b. This macro is used for
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.\" constants that must be scoped in Java, but are global otherwise.
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.\" This macro takes two arguments:
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.\" + the class
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.\" + the name within the class or following the prefix
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.de Sj
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.ie '\*[TYPE]'JAVA'\{\
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.TP 5
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Db.\\$1\}
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.el\{\
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.TP 5
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\\$1\}
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..
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.\" The general information text macro.
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.de Gn
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.ie '\*[TYPE]'C'\{The DB library is a family of groups of functions that provides a modular
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programming interface to transactions and record-oriented file access.
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The library includes support for transactions, locking, logging and file
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page caching, as well as various indexed access methods.
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Many of the functional groups (e.g., the file page caching functions)
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are useful independent of the other DB functions,
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although some functional groups are explicitly based on other functional
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groups (e.g., transactions and logging).
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\}
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.el\{The DB library is a family of classes that provides a modular
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programming interface to transactions and record-oriented file access.
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The library includes support for transactions, locking, logging and file
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page caching, as well as various indexed access methods.
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Many of the classes (e.g., the file page caching class)
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are useful independent of the other DB classes,
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although some classes are explicitly based on other classes
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(e.g., transactions and logging).
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\}
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For a general description of the DB package, see
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.IR db_intro (3).
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..
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.\" The library error macro, the local error macro.
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.\" These macros take one argument:
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.\" + the function name.
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.de Ee
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The
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.I \\$1
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.ie '\*[TYPE]'C'\{function may fail and return
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.I errno
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\}
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.el\{method may fail and throw a
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.IR DbException (3)
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.if '\*[TYPE]'CXX'\{
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or return
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.I errno
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\}
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\}
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for any of the errors specified for the following DB and library functions:
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..
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.de Ec
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In addition, the
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.I \\$1
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.ie '\*[TYPE]'C'\{function may fail and return
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.I errno
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\}
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.el\{method may fail and throw a
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.IR DbException (3)
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.ie '\*[TYPE]'CXX'\{or return
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.I errno
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\}
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.el\{encapsulating an
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.I errno
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\}
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\}
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for the following conditions:
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..
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.de Ea
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[EAGAIN]
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A lock was unavailable.
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..
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.de Eb
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[EBUSY]
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The shared memory region was in use and the force flag was not set.
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..
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.de Em
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[EAGAIN]
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The shared memory region was locked and (repeatedly) unavailable.
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..
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.de Ei
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[EINVAL]
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An invalid flag value or parameter was specified.
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..
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.de Es
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[EACCES]
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An attempt was made to modify a read-only database.
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..
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.de Et
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The DB_THREAD flag was specified and spinlocks are not implemented for
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this architecture.
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..
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.de Ep
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[EPERM]
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Database corruption was detected.
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All subsequent database calls (other than
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.ie '\*[TYPE]'C'\{\
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.IR DB->close )
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\}
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.el\{\
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.IR Db::close )
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\}
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will return EPERM.
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..
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.de Ek
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.if '\*[TYPE]'CXX'\{\
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Methods marked as returning
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.I errno
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will, by default, throw an exception that encapsulates the error information.
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The default error behavior can be changed, see
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.IR DbException (3).
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\}
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..
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.\" The SEE ALSO text macro
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.de Sa
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.\" make the line long for nroff.
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.if n .ll 72
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.nh
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.na
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.IR db_archive (1),
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.IR db_checkpoint (1),
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.IR db_deadlock (1),
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.IR db_dump (1),
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.IR db_load (1),
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.IR db_recover (1),
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.IR db_stat (1),
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.IR db_intro (3),
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.ie '\*[TYPE]'C'\{\
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.IR db_appinit (3),
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.IR db_cursor (3),
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.IR db_dbm (3),
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.IR db_internal (3),
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.IR db_lock (3),
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.IR db_log (3),
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.IR db_mpool (3),
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.IR db_open (3),
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.IR db_thread (3),
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.IR db_txn (3)
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\}
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.el\{\
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.IR db_internal (3),
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.IR db_thread (3),
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.IR Db (3),
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.IR Dbc (3),
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.IR DbEnv (3),
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.IR DbException (3),
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.IR DbInfo (3),
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.IR DbLock (3),
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.IR DbLockTab (3),
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.IR DbLog (3),
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.IR DbLsn (3),
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.IR DbMpool (3),
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.if !'\*[TYPE]'JAVA'\{\
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.IR DbMpoolFile (3),
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\}
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.IR Dbt (3),
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.IR DbTxn (3),
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.IR DbTxnMgr (3)
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\}
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.ad
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.Hy
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|
..
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.\" The function header macro.
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.\" This macro takes one argument:
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.\" + the function name.
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.de Fn
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.in 2
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.I \\$1
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.in
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..
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.\" The XXX_open function text macro, for merged create/open calls.
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.\" This macro takes two arguments:
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.\" + the interface, e.g., "transaction region"
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.\" + the prefix, e.g., "txn" (or the class name for C++, e.g., "DbTxn")
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.de Co
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.ie '\*[TYPE]'C'\{\
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.Fn \\$2_open
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The
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.I \\$2_open
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|
function copies a pointer, to the \\$1 identified by the
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.B directory
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.IR dir ,
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into the memory location referenced by
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.IR regionp .
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.PP
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If the
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.I dbenv
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argument to
|
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.I \\$2_open
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was initialized using
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.IR db_appinit ,
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.I dir
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|
is interpreted as described by
|
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.IR db_appinit (3).
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\}
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.el\{\
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.Fn \\$2::open
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The
|
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.I \\$2::open
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.ie '\*[TYPE]'CXX'\{\
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method copies a pointer, to the \\$1 identified by the
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.B directory
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.IR dir ,
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into the memory location referenced by
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.IR regionp .
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\}
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.el\{\
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method returns a \\$1 identified by the
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.B directory
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.IR dir .
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\}
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.PP
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If the
|
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.I dbenv
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argument to
|
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.I \\$2::open
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was initialized using
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.IR DbEnv::appinit ,
|
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.I dir
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is interpreted as described by
|
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.IR DbEnv (3).
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\}
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.PP
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Otherwise,
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if
|
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.I dir
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is not NULL,
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it is interpreted relative to the current working directory of the process.
|
|
If
|
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.I dir
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is NULL,
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|
the following environment variables are checked in order:
|
|
``TMPDIR'', ``TEMP'', and ``TMP''.
|
|
If one of them is set,
|
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\\$1 files are created relative to the directory it specifies.
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|
If none of them are set, the first possible one of the following
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|
directories is used:
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.IR /var/tmp ,
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|
.IR /usr/tmp ,
|
|
.IR /temp ,
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|
.IR /tmp ,
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|
.I C:/temp
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|
and
|
|
.IR C:/tmp .
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.PP
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|
All files associated with the \\$1 are created in this directory.
|
|
This directory must already exist when
|
|
.ie '\*[TYPE]'C'\{
|
|
\\$1_open
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|
\}
|
|
.el\{\
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|
\\$2::open
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|
\}
|
|
is called.
|
|
If the \\$1 already exists,
|
|
the process must have permission to read and write the existing files.
|
|
If the \\$1 does not already exist,
|
|
it is optionally created and initialized.
|
|
..
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|
.\" The common close language macro, for discarding created regions
|
|
.\" This macro takes one argument:
|
|
.\" + the function prefix, e.g., txn (the class name for C++, e.g., DbTxn)
|
|
.de Cc
|
|
In addition, if the
|
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.I dir
|
|
argument to
|
|
.ie '\*[TYPE]'C'\{\
|
|
.ds Va db_appinit
|
|
.ds Vo \\$1_open
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|
.ds Vu \\$1_unlink
|
|
\}
|
|
.el\{\
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|
.ds Va DbEnv::appinit
|
|
.ds Vo \\$1::open
|
|
.ds Vu \\$1::unlink
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|
\}
|
|
.I \\*(Vo
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was NULL
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and
|
|
.I dbenv
|
|
was not initialized using
|
|
.IR \\*(Va ,
|
|
.if '\\$1'memp'\{\
|
|
or the DB_MPOOL_PRIVATE flag was set,
|
|
\}
|
|
all files created for this shared region will be removed,
|
|
as if
|
|
.I \\*(Vu
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|
were called.
|
|
.rm Va
|
|
.rm Vo
|
|
.rm Vu
|
|
..
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|
.\" The DB_ENV information macro.
|
|
.\" This macro takes two arguments:
|
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.\" + the function called to open, e.g., "txn_open"
|
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.\" + the function called to close, e.g., "txn_close"
|
|
.de En
|
|
.ie '\*[TYPE]'C'\{\
|
|
based on the
|
|
.I dbenv
|
|
argument to
|
|
.IR \\$1 ,
|
|
which is a pointer to a structure of type DB_ENV (typedef'd in <db.h>).
|
|
Applications will normally use the same DB_ENV structure (initialized
|
|
by
|
|
.IR db_appinit (3)),
|
|
as an argument to all of the subsystems in the DB package.
|
|
.PP
|
|
References to the DB_ENV structure are maintained by DB,
|
|
so it may not be discarded until the last close function,
|
|
corresponding to an open function for which it was an argument,
|
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has returned.
|
|
In order to ensure compatibility with future releases of DB, all fields of
|
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the DB_ENV structure that are not explicitly set should be initialized to 0
|
|
before the first time the structure is used.
|
|
Do this by declaring the structure external or static, or by calling the C
|
|
library routine
|
|
.IR bzero (3)
|
|
or
|
|
.IR memset (3).
|
|
.PP
|
|
The fields of the DB_ENV structure used by
|
|
.I \\$1
|
|
are described below.
|
|
.if '\*[TYPE]'CXX'\{\
|
|
As references to the DB_ENV structure may be maintained by
|
|
.IR \\$1 ,
|
|
it is necessary that the DB_ENV structure and memory it references be valid
|
|
until the
|
|
.I \\$2
|
|
function is called.
|
|
\}
|
|
.ie '\\$1'db_appinit'\{The
|
|
.I dbenv
|
|
argument may not be NULL.
|
|
If any of the fields of the
|
|
.I dbenv
|
|
are set to 0,
|
|
defaults appropriate for the system are used where possible.
|
|
\}
|
|
.el\{If
|
|
.I dbenv
|
|
is NULL
|
|
or any of its fields are set to 0,
|
|
defaults appropriate for the system are used where possible.
|
|
\}
|
|
.PP
|
|
The following fields in the DB_ENV structure may be initialized before calling
|
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.IR \\$1 :
|
|
\}
|
|
.el\{\
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|
based on which set methods have been used.
|
|
It is expected that applications will use a single DbEnv object as the
|
|
argument to all of the subsystems in the DB package.
|
|
The fields of the DbEnv object used by
|
|
.I \\$1
|
|
are described below.
|
|
As references to the DbEnv object may be maintained by
|
|
.IR \\$1 ,
|
|
it is necessary that the DbEnv object and memory it references be valid
|
|
until the object is destroyed.
|
|
.ie '\\$1'appinit'\{\
|
|
The
|
|
.I dbenv
|
|
argument may not be NULL.
|
|
If any of the fields of the
|
|
.I dbenv
|
|
are set to 0,
|
|
defaults appropriate for the system are used where possible.
|
|
\}
|
|
.el\{\
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|
Any of the DbEnv fields that are not explicitly set will default to
|
|
appropriate values.
|
|
\}
|
|
.PP
|
|
The following fields in the DbEnv object may be initialized, using the
|
|
appropriate set method, before calling
|
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.IR \\$1 :
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\}
|
|
..
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|
.\" The DB_ENV common fields macros.
|
|
.de Se
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|
.if '\*[TYPE]'JAVA'\{\
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|
.TP 5
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DbErrcall db_errcall;
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|
.ns
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|
.TP 5
|
|
String db_errpfx;
|
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.ns
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.TP 5
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int db_verbose;
|
|
The error fields of the DbEnv behave as described for
|
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.IR DbEnv (3).
|
|
\}
|
|
.ie '\*[TYPE]'CXX'\{\
|
|
.TP 5
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|
void *(*db_errcall)(char *db_errpfx, char *buffer);
|
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.ns
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|
.TP 5
|
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FILE *db_errfile;
|
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.ns
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|
.TP 5
|
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const char *db_errpfx;
|
|
.ns
|
|
.TP 5
|
|
class ostream *db_error_stream;
|
|
.ns
|
|
.TP 5
|
|
int db_verbose;
|
|
The error fields of the DbEnv behave as described for
|
|
.IR DbEnv (3).
|
|
\}
|
|
.el\{\
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|
void *(*db_errcall)(char *db_errpfx, char *buffer);
|
|
.ns
|
|
.TP 5
|
|
FILE *db_errfile;
|
|
.ns
|
|
.TP 5
|
|
const char *db_errpfx;
|
|
.ns
|
|
.TP 5
|
|
int db_verbose;
|
|
The error fields of the DB_ENV behave as described for
|
|
.IR db_appinit (3).
|
|
.sp
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|
\}
|
|
..
|
|
.\" The open flags.
|
|
.de Fm
|
|
The
|
|
.I flags
|
|
and
|
|
.I mode
|
|
arguments specify how files will be opened and/or created when they
|
|
don't already exist.
|
|
The flags value is specified by
|
|
.BR or 'ing
|
|
together one or more of the following values:
|
|
.Sj DB_CREATE
|
|
Create any underlying files, as necessary.
|
|
If the files do not already exist and the DB_CREATE flag is not specified,
|
|
the call will fail.
|
|
..
|
|
.\" DB_THREAD open flag macro.
|
|
.\" This macro takes two arguments:
|
|
.\" + the open function name
|
|
.\" + the object it returns.
|
|
.de Ft
|
|
.TP 5
|
|
.Sj DB_THREAD
|
|
Cause the \\$2 handle returned by the
|
|
.I \\$1
|
|
.Al function method
|
|
to be useable by multiple threads within a single address space,
|
|
i.e., to be ``free-threaded''.
|
|
.if '\*[TYPE]'JAVA'\{\
|
|
Threading is assumed in the Java API,
|
|
so no special flags are required,
|
|
and DB functions will always behave as if the DB_THREAD flag was specified.
|
|
\}
|
|
..
|
|
.\" The mode macro.
|
|
.\" This macro takes one argument:
|
|
.\" + the subsystem name.
|
|
.de Mo
|
|
All files created by the \\$1 are created with mode
|
|
.I mode
|
|
(as described in
|
|
.IR chmod (2))
|
|
and modified by the process' umask value at the time of creation (see
|
|
.IR umask (2)).
|
|
The group ownership of created files is based on the system and directory
|
|
defaults, and is not further specified by DB.
|
|
..
|
|
.\" The application exits macro.
|
|
.\" This macro takes one argument:
|
|
.\" + the application name.
|
|
.de Ex
|
|
The
|
|
.I \\$1
|
|
utility exits 0 on success, and >0 if an error occurs.
|
|
..
|
|
.\" The application -h section.
|
|
.\" This macro takes one argument:
|
|
.\" + the application name
|
|
.de Dh
|
|
DB_HOME
|
|
If the
|
|
.B \-h
|
|
option is not specified and the environment variable
|
|
.I DB_HOME
|
|
is set, it is used as the path of the database home, as described in
|
|
.IR db_appinit (3).
|
|
..
|
|
.\" The function DB_HOME ENVIRONMENT VARIABLES section.
|
|
.\" This macro takes one argument:
|
|
.\" + the open function name
|
|
.de Eh
|
|
DB_HOME
|
|
If the
|
|
.I dbenv
|
|
argument to
|
|
.I \\$1
|
|
was initialized using
|
|
.IR db_appinit ,
|
|
the environment variable DB_HOME may be used as the path of the database
|
|
home for the interpretation of the
|
|
.I dir
|
|
argument to
|
|
.IR \\$1 ,
|
|
as described in
|
|
.IR db_appinit (3).
|
|
.if \\n(.$>1 \{Specifically,
|
|
.I \\$1
|
|
is affected by the configuration string value of \\$2.\}
|
|
..
|
|
.\" The function TMPDIR ENVIRONMENT VARIABLES section.
|
|
.\" This macro takes two arguments:
|
|
.\" + the interface, e.g., "transaction region"
|
|
.\" + the prefix, e.g., "txn" (or the class name for C++, e.g., "DbTxn")
|
|
.de Ev
|
|
TMPDIR
|
|
If the
|
|
.I dbenv
|
|
argument to
|
|
.ie '\*[TYPE]'C'\{\
|
|
.ds Vo \\$2_open
|
|
\}
|
|
.el\{\
|
|
.ds Vo \\$2::open
|
|
\}
|
|
.I \\*(Vo
|
|
was NULL or not initialized using
|
|
.IR db_appinit ,
|
|
the environment variable TMPDIR may be used as the directory in which to
|
|
create the \\$1,
|
|
as described in the
|
|
.I \\*(Vo
|
|
section above.
|
|
.rm Vo
|
|
..
|
|
.\" The unused flags macro.
|
|
.de Fl
|
|
The
|
|
.I flags
|
|
parameter is currently unused, and must be set to 0.
|
|
..
|
|
.\" The no-space TP macro.
|
|
.de Nt
|
|
.br
|
|
.ns
|
|
.TP 5
|
|
..
|
|
.\" The return values of the functions macros.
|
|
.\" Rc is the standard two-value return with a suffix for more values.
|
|
.\" Ro is the standard two-value return but there were previous values.
|
|
.\" Rt is the standard two-value return, returning errno, 0, or < 0.
|
|
.\" These macros take one argument:
|
|
.\" + the routine name
|
|
.de Rc
|
|
The
|
|
.I \\$1
|
|
.ie '\*[TYPE]'C'\{function returns the value of
|
|
.I errno
|
|
on failure,
|
|
0 on success,
|
|
\}
|
|
.el\{method throws a
|
|
.IR DbException (3)
|
|
.ie '\*[TYPE]'CXX'\{or returns the value of
|
|
.I errno
|
|
on failure,
|
|
0 on success,
|
|
\}
|
|
.el\{that encapsulates an
|
|
.I errno
|
|
on failure,
|
|
\}
|
|
\}
|
|
..
|
|
.de Ro
|
|
Otherwise, the
|
|
.I \\$1
|
|
.ie '\*[TYPE]'C'\{function returns the value of
|
|
.I errno
|
|
on failure and 0 on success.
|
|
\}
|
|
.el\{method throws a
|
|
.IR DbException (3)
|
|
.ie '\*[TYPE]'CXX'\{or returns the value of
|
|
.I errno
|
|
on failure and 0 on success.
|
|
\}
|
|
.el\{that encapsulates an
|
|
.I errno
|
|
on failure,
|
|
\}
|
|
\}
|
|
..
|
|
.de Rt
|
|
The
|
|
.I \\$1
|
|
.ie '\*[TYPE]'C'\{function returns the value of
|
|
.I errno
|
|
on failure and 0 on success.
|
|
\}
|
|
.el\{method throws a
|
|
.IR DbException (3)
|
|
.ie '\*[TYPE]'CXX'\{or returns the value of
|
|
.I errno
|
|
on failure and 0 on success.
|
|
\}
|
|
.el\{that encapsulates an
|
|
.I errno
|
|
on failure.
|
|
\}
|
|
\}
|
|
..
|
|
.\" The TXN id macro.
|
|
.de Tx
|
|
.IP
|
|
If the file is being accessed under transaction protection,
|
|
the
|
|
.I txnid
|
|
parameter is a transaction ID returned from
|
|
.IR txn_begin ,
|
|
otherwise, NULL.
|
|
..
|
|
.\" The XXX_unlink function text macro.
|
|
.\" This macro takes two arguments:
|
|
.\" + the interface, e.g., "transaction region"
|
|
.\" + the prefix (for C++, this is the class name)
|
|
.de Un
|
|
.ie '\*[TYPE]'C'\{\
|
|
.ds Va db_appinit
|
|
.ds Vc \\$2_close
|
|
.ds Vo \\$2_open
|
|
.ds Vu \\$2_unlink
|
|
\}
|
|
.el\{\
|
|
.ds Va DbEnv::appinit
|
|
.ds Vc \\$2::close
|
|
.ds Vo \\$2::open
|
|
.ds Vu \\$2::unlink
|
|
\}
|
|
.Fn \\*(Vu
|
|
The
|
|
.I \\*(Vu
|
|
.Al function method
|
|
destroys the \\$1 identified by the directory
|
|
.IR dir ,
|
|
removing all files used to implement the \\$1.
|
|
.ie '\\$2'log' \{(The log files themselves and the directory
|
|
.I dir
|
|
are not removed.)\}
|
|
.el \{(The directory
|
|
.I dir
|
|
is not removed.)\}
|
|
If there are processes that have called
|
|
.I \\*(Vo
|
|
without calling
|
|
.I \\*(Vc
|
|
(i.e., there are processes currently using the \\$1),
|
|
.I \\*(Vu
|
|
will fail without further action,
|
|
unless the force flag is set,
|
|
in which case
|
|
.I \\*(Vu
|
|
will attempt to remove the \\$1 files regardless of any processes
|
|
still using the \\$1.
|
|
.PP
|
|
The result of attempting to forcibly destroy the region when a process
|
|
has the region open is unspecified.
|
|
Processes using a shared memory region maintain an open file descriptor
|
|
for it.
|
|
On UNIX systems, the region removal should succeed
|
|
and processes that have already joined the region should continue to
|
|
run in the region without change,
|
|
however processes attempting to join the \\$1 will either fail or
|
|
attempt to create a new region.
|
|
On other systems, e.g., WNT, where the
|
|
.IR unlink (2)
|
|
system call will fail if any process has an open file descriptor
|
|
for the file,
|
|
the region removal will fail.
|
|
.PP
|
|
In the case of catastrophic or system failure,
|
|
database recovery must be performed (see
|
|
.IR db_recover (1)
|
|
or the DB_RECOVER and DB_RECOVER_FATAL flags to
|
|
.IR \\*(Va (3)).
|
|
Alternatively, if recovery is not required because no database state is
|
|
maintained across failures,
|
|
it is possible to clean up a \\$1 by removing all of the
|
|
files in the directory specified to the
|
|
.I \\*(Vo
|
|
.Al function, method,
|
|
as \\$1 files are never created in any directory other than the one
|
|
specified to
|
|
.IR \\*(Vo .
|
|
Note, however,
|
|
that this has the potential to remove files created by the other DB
|
|
subsystems in this database environment.
|
|
.PP
|
|
.Rt \\*(Vu
|
|
.rm Va
|
|
.rm Vo
|
|
.rm Vu
|
|
.rm Vc
|
|
..
|
|
.\" Signal paragraph for standard utilities.
|
|
.\" This macro takes one argument:
|
|
.\" + the utility name.
|
|
.de Si
|
|
The
|
|
.I \\$1
|
|
utility attaches to DB shared memory regions.
|
|
In order to avoid region corruption,
|
|
it should always be given the chance to detach and exit gracefully.
|
|
To cause
|
|
.I \\$1
|
|
to clean up after itself and exit,
|
|
send it an interrupt signal (SIGINT).
|
|
..
|
|
.\" Logging paragraph for standard utilities.
|
|
.\" This macro takes one argument:
|
|
.\" + the utility name.
|
|
.de Pi
|
|
.B \-L
|
|
Log the execution of the \\$1 utility to the specified file in the
|
|
following format, where ``###'' is the process ID, and the date is
|
|
the time the utility starting running.
|
|
.sp
|
|
\\$1: ### Wed Jun 15 01:23:45 EDT 1995
|
|
.sp
|
|
This file will be removed if the \\$1 utility exits gracefully.
|
|
..
|
|
.\" Malloc paragraph.
|
|
.\" This macro takes one argument:
|
|
.\" + the allocated object
|
|
.de Ma
|
|
.if !'\*[TYPE]'JAVA'\{\
|
|
\\$1 are created in allocated memory.
|
|
If
|
|
.I db_malloc
|
|
is non-NULL,
|
|
it is called to allocate the memory,
|
|
otherwise,
|
|
the library function
|
|
.IR malloc (3)
|
|
is used.
|
|
The function
|
|
.I db_malloc
|
|
must match the calling conventions of the
|
|
.IR malloc (3)
|
|
library routine.
|
|
Regardless,
|
|
the caller is responsible for deallocating the returned memory.
|
|
To deallocate the returned memory,
|
|
free each returned memory pointer;
|
|
pointers inside the memory do not need to be individually freed.
|
|
\}
|
|
..
|
|
.\" Underlying function paragraph.
|
|
.\" This macro takes two arguments:
|
|
.\" + the function name
|
|
.\" + the utility name
|
|
.de Uf
|
|
The
|
|
.I \\$1
|
|
.Al function method
|
|
is the underlying function used by the
|
|
.IR \\$2 (1)
|
|
utility.
|
|
See the source code for the
|
|
.I \\$2
|
|
utility for an example of using
|
|
.I \\$1
|
|
in a UNIX environment.
|
|
..
|
|
.\" Underlying function paragraph, for C++.
|
|
.\" This macro takes three arguments:
|
|
.\" + the C++ method name
|
|
.\" + the function name for C
|
|
.\" + the utility name
|
|
.de Ux
|
|
The
|
|
.I \\$1
|
|
method is based on the C
|
|
.I \\$2
|
|
function, which
|
|
is the underlying function used by the
|
|
.IR \\$3 (1)
|
|
utility.
|
|
See the source code for the
|
|
.I \\$3
|
|
utility for an example of using
|
|
.I \\$2
|
|
in a UNIX environment.
|
|
..
|
|
.TH DB_ARCHIVE 1 "May 3, 1998"
|
|
.UC 7
|
|
.SH NAME
|
|
db_archive \- the DB database archiver
|
|
.SH SYNOPSIS
|
|
\fBdb_archive\fP [\fB-alsv\fP] [\fB-h home\fP]
|
|
.SH DESCRIPTION
|
|
The
|
|
.I db_archive
|
|
utility writes the pathnames of log files that are no longer in use (e.g.,
|
|
no longer involved in active transactions),
|
|
to the standard output, one pathname per line.
|
|
These log files should be written to backup media to provide for recovery
|
|
in the case of catastrophic failure (which also requires a snapshot of the
|
|
database files),
|
|
but they may then be deleted from the system to reclaim disk space.
|
|
.PP
|
|
The options are as follows:
|
|
.TP 5
|
|
.B \-a
|
|
Write all pathnames as absolute pathnames,
|
|
instead of relative to the database home directories.
|
|
.TP 5
|
|
.B \-h
|
|
Specify a home directory for the database.
|
|
.TP 5
|
|
.B \-l
|
|
Write out the pathnames of all of the database log files,
|
|
whether or not they are involved in active transactions.
|
|
.TP 5
|
|
.B \-s
|
|
Write the pathnames of all of the database files that need to be archived
|
|
in order to recover the database from catastrophic failure.
|
|
If any of the database files have not been accessed during the lifetime of
|
|
the current log files,
|
|
.I db_archive
|
|
will not include them in this output.
|
|
.sp
|
|
It is possible that some of the files referenced in the log have since
|
|
been deleted from the system.
|
|
In this case,
|
|
.I db_archive
|
|
will ignore them.
|
|
When
|
|
.IR db_recover (1)
|
|
is run,
|
|
any files referenced in the log that are not present during recovery are
|
|
assumed to have been deleted and will not be recovered.
|
|
.TP 5
|
|
.B \-v
|
|
Run in verbose mode, listing the checkpoints in the log files as they
|
|
are reviewed.
|
|
.PP
|
|
.Si db_archive
|
|
.PP
|
|
.Ex db_archive
|
|
.SH "DB ARCHIVAL PROCEDURES
|
|
There are two aspects to managing the recoverability and disk consumption
|
|
of your DB databases.
|
|
First, you may want to periodically create snapshots of your databases
|
|
to make it possible to recover them from catastrophic failure.
|
|
Second, you'll want to periodically remove log files in order to conserve
|
|
on disk space.
|
|
The two procedures are distinct from each other, and you cannot remove the
|
|
current log files simply because you have created a database snapshot.
|
|
.PP
|
|
To create a snapshot of your database that can be used to recover
|
|
from catastrophic failure, the following steps should be taken:
|
|
.TP 5
|
|
1.
|
|
Run
|
|
.I db_archive
|
|
\-s to identify all of the database data files that must be saved,
|
|
and copy them to a backup device, (e.g., tape).
|
|
If the database files are stored in a separate directory from the
|
|
other database files, it may be simpler to archive the directory
|
|
itself instead of the individual files.
|
|
.sp
|
|
.ft B
|
|
More importantly, if any of the database files have not been accessed during
|
|
the lifetime of the current log files, db_archive will not list them in its
|
|
output!
|
|
.ft R
|
|
For this reason,
|
|
it may be important to use a separate database file directory,
|
|
archiving it instead of the files listed by
|
|
.IR db_archive .
|
|
.TP 5
|
|
2.
|
|
If your database is currently active,
|
|
i.e., you are reading and writing to the database files while the snapshot
|
|
is being taken,
|
|
run
|
|
.I db_archive
|
|
\-l to identify the database log files,
|
|
and copy them to a backup device, (e.g., tape).
|
|
If the database log files are stored in a separate directory from the
|
|
other database files, it may be simpler to archive the directory itself
|
|
instead of the individual files.
|
|
.PP
|
|
Note that the order of these operations is important,
|
|
and that the database files
|
|
.B must
|
|
be archived before the log files.
|
|
.PP
|
|
The DB library supports on-line backups,
|
|
and it is not necessary to stop reading or writing your databases during
|
|
the time when you create this snapshot.
|
|
Note however,
|
|
that the snapshot of an active database will be consistent as of some
|
|
unspecified time between the start of the archival and when archival is
|
|
completed.
|
|
To create a snapshot as of a specific time,
|
|
you must stop reading and writing your databases for the entire time of
|
|
the archival, force a checkpoint (see
|
|
.IR db_checkpoint (1)),
|
|
and then archive the files listed by the
|
|
.I db_archive
|
|
command's
|
|
.B \-s
|
|
and
|
|
.B \-l
|
|
options.
|
|
.PP
|
|
Once these steps are completed,
|
|
your database can be recovered from catastrophic failure to its state
|
|
as of the time the archival was done.
|
|
To update your snapshot so that recovery from catastrophic failure is
|
|
possible up to a new point in time,
|
|
repeat step #2, copying all existing log files to a backup device.
|
|
.PP
|
|
Each time that a complete snapshot is made,
|
|
i.e. all database and log files are copied to backup media,
|
|
you may discard all previous snapshots and saved log files.
|
|
.PP
|
|
The time to restore from catastrophic failure is a function of the number
|
|
of log records that have been written since the snapshot was originally
|
|
created.
|
|
Perhaps more importantly,
|
|
the more separate pieces of backup media you use,
|
|
the more likely that you will have a problem reading from one of them.
|
|
For these reasons,
|
|
it is often best to make snapshots on a regular basis.
|
|
.PP
|
|
.ft B
|
|
For archival safety remember to ensure that you have multiple copies of
|
|
your database backups,
|
|
that you verify that your archival media is error-free,
|
|
and that copies of your backups are stored off-site!
|
|
.ft R
|
|
.PP
|
|
To restore your database after catastrophic failure,
|
|
the following steps should be taken:
|
|
.TP 5
|
|
1.
|
|
Restore the copies of the database files from the backup media.
|
|
.TP 5
|
|
2.
|
|
Restore the copies of the log files from the backup media,
|
|
.BR "in the order in which they were written" .
|
|
(It's possible that the same log file appears on multiple backups,
|
|
and you only want the most recent version of that log file!)
|
|
.TP 5
|
|
3.
|
|
Run
|
|
.I db_recover
|
|
\-c
|
|
to recover the database.
|
|
.PP
|
|
It is possible to recreate the database in a location different than the
|
|
original,
|
|
by specifying appropriate pathnames to the \-h option of the
|
|
.I db_recover
|
|
utility.
|
|
.PP
|
|
To remove log files, the following steps should be taken:
|
|
.TP 5
|
|
1.
|
|
If you are concerned with catastrophic failure,
|
|
first copy them to backup media (e.g., tape), as described above.
|
|
This is because log files are necessary for recovery from catastrophic
|
|
failure.
|
|
.TP 5
|
|
2.
|
|
Run
|
|
.IR db_archive ,
|
|
without options,
|
|
to identify all of the log files that are no longer in use (e.g., involved
|
|
in an active transaction).
|
|
.TP 5
|
|
3.
|
|
Remove those log files from the system.
|
|
.SH "ENVIRONMENT VARIABLES"
|
|
The following environment variables affect the execution of
|
|
.IR db_archive :
|
|
.TP 5
|
|
.Dh db_archive
|
|
.SH "SEE ALSO"
|
|
.Gn
|
|
.PP
|
|
.Sa
|