gecko-dev/db/man/man.roff/db_checkpoint.1

.ds TYPE C
.\"
.\" See the file LICENSE for redistribution information.
.\"
.\" Copyright (c) 1996, 1997, 1998
.\"	Sleepycat Software.  All rights reserved.
.\"
.\"	@(#)db_checkpoint.so	10.11 (Sleepycat) 5/3/98
.\"
.\"
.\" See the file LICENSE for redistribution information.
.\"
.\" Copyright (c) 1997, 1998
.\"	Sleepycat Software.  All rights reserved.
.\"
.\"	@(#)macros.so	10.45 (Sleepycat) 5/4/98
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.\" Scoped name macro.
.\" Produces a_b, a::b, a.b depending on language
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.\" Scoped name for Java.
.\" Produces Db.b, for Java, otherwise just b.  This macro is used for
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.TP 5
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\\$1\}
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.\" The general information text macro.
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.ie '\*[TYPE]'C'\{The DB library is a family of groups of functions that provides a modular
programming interface to transactions and record-oriented file access.
The library includes support for transactions, locking, logging and file
page caching, as well as various indexed access methods.
Many of the functional groups (e.g., the file page caching functions)
are useful independent of the other DB functions,
although some functional groups are explicitly based on other functional
groups (e.g., transactions and logging).
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.el\{The DB library is a family of classes that provides a modular
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are useful independent of the other DB classes,
although some classes are explicitly based on other classes
(e.g., transactions and logging).
\}
For a general description of the DB package, see
.IR db_intro (3).
..
.\" The library error macro, the local error macro.
.\" These macros take one argument:
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The
.I \\$1
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.I errno
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.el\{method may fail and throw a
.IR DbException (3)
.if '\*[TYPE]'CXX'\{
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for any of the errors specified for the following DB and library functions:
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In addition, the
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.IR DbException (3)
.ie '\*[TYPE]'CXX'\{or return
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for the following conditions:
..
.de Ea
[EAGAIN]
A lock was unavailable.
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[EBUSY]
The shared memory region was in use and the force flag was not set.
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.de Em
[EAGAIN]
The shared memory region was locked and (repeatedly) unavailable.
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[EINVAL]
An invalid flag value or parameter was specified.
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[EACCES]
An attempt was made to modify a read-only database.
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The DB_THREAD flag was specified and spinlocks are not implemented for
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Database corruption was detected.
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Methods marked as returning
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.\" The SEE ALSO text macro
.de Sa
.\" make the line long for nroff.
.if n .ll 72
.nh
.na
.IR db_archive (1),
.IR db_checkpoint (1),
.IR db_deadlock (1),
.IR db_dump (1),
.IR db_load (1),
.IR db_recover (1),
.IR db_stat (1),
.IR db_intro (3),
.ie '\*[TYPE]'C'\{\
.IR db_appinit (3),
.IR db_cursor (3),
.IR db_dbm (3),
.IR db_internal (3),
.IR db_lock (3),
.IR db_log (3),
.IR db_mpool (3),
.IR db_open (3),
.IR db_thread (3),
.IR db_txn (3)
\}
.el\{\
.IR db_internal (3),
.IR db_thread (3),
.IR Db (3),
.IR Dbc (3),
.IR DbEnv (3),
.IR DbException (3),
.IR DbInfo (3),
.IR DbLock (3),
.IR DbLockTab (3),
.IR DbLog (3),
.IR DbLsn (3),
.IR DbMpool (3),
.if !'\*[TYPE]'JAVA'\{\
.IR DbMpoolFile (3),
\}
.IR Dbt (3),
.IR DbTxn (3),
.IR DbTxnMgr (3)
\}
.ad
.Hy
..
.\" The function header macro.
.\" This macro takes one argument:
.\"	+ the function name.
.de Fn
.in 2
.I \\$1
.in
..
.\" The XXX_open function text macro, for merged create/open calls.
.\" 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")
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.ie '\*[TYPE]'C'\{\
.Fn \\$2_open
The
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If the
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Otherwise,
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.I dir
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it is interpreted relative to the current working directory of the process.
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.I dir
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``TMPDIR'', ``TEMP'', and ``TMP''.
If one of them is set,
\\$1 files are created relative to the directory it specifies.
If none of them are set, the first possible one of the following
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.IR /var/tmp ,
.IR /usr/tmp ,
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.IR C:/tmp .
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All files associated with the \\$1 are created in this directory.
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.ie '\*[TYPE]'C'\{
\\$1_open
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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)
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.I dir
argument to
.ie '\*[TYPE]'C'\{\
.ds Va db_appinit
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.\" The DB_ENV information macro.
.\" This macro takes two arguments:
.\"	+ the function called to open, e.g., "txn_open"
.\"	+ the function called to close, e.g., "txn_close"
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.ie '\*[TYPE]'C'\{\
based on the
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References to the DB_ENV structure are maintained by DB,
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Do this by declaring the structure external or static, or by calling the C
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are described below.
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The following fields in the DbEnv object may be initialized, using the
appropriate set method, before calling
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.\" The DB_ENV common fields macros.
.de Se
.if '\*[TYPE]'JAVA'\{\
.TP 5
DbErrcall db_errcall;
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String db_errpfx;
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int db_verbose;
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void *(*db_errcall)(char *db_errpfx, char *buffer);
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void *(*db_errcall)(char *db_errpfx, char *buffer);
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.TP 5
int db_verbose;
The error fields of the DB_ENV behave as described for
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.sp
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.\" The open flags.
.de Fm
The
.I flags
and
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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,
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.if '\*[TYPE]'JAVA'\{\
Threading is assumed in the Java API,
so no special flags are required,
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.\" The mode macro.
.\" This macro takes one argument:
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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.
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.\" The application -h section.
.\" This macro takes one argument:
.\"	+ the application name
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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).
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.\" The function DB_HOME ENVIRONMENT VARIABLES section.
.\" This macro takes one argument:
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DB_HOME
If the
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argument to
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was initialized using
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as described in
.IR db_appinit (3).
.if \\n(.$>1 \{Specifically,
.I \\$1
is affected by the configuration string value of \\$2.\}
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.\" 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")
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TMPDIR
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.ie '\*[TYPE]'C'\{\
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.el\{\
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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
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The
.I \\$1
.ie '\*[TYPE]'C'\{function returns the value of
.I errno
on failure,
0 on success,
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.el\{that encapsulates an
.I errno
on failure,
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.de Ro
Otherwise, the
.I \\$1
.ie '\*[TYPE]'C'\{function returns the value of
.I errno
on failure and 0 on success.
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.el\{that encapsulates an
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The
.I \\$1
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.I errno
on failure and 0 on success.
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.I errno
on failure and 0 on success.
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.el\{that encapsulates an
.I errno
on failure.
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\}
..
.\" 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
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.el\{\
.ds Va DbEnv::appinit
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.ds Vo \\$2::open
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.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.
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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
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.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
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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_CHECKPOINT 1 "May 3, 1998"
.UC 7
.SH NAME
db_checkpoint \- the DB database checkpoint utility
.SH SYNOPSIS
.nf
\fBdb_checkpoint\fP [\fB-1v\fP] [\fB-h home\fP] [\fB-k kbytes\fP] [\fB-L file\fP] [\fB-p min\fP]
.fi
.SH DESCRIPTION
The
.I db_checkpoint
utility is a daemon process that monitors the database log and periodically
calls
.IR txn_checkpoint (3)
to checkpoint it.
.PP
The options are as follows:
.TP 5
.B \-1
Checkpoint the log once, and then exit.
.TP 5
.B \-h
Specify a home directory for the database.
.TP 5
.B \-k
Checkpoint the database at least as often as every
.I kbytes
of log file are written.
.TP 5
.Pi db_checkpoint
.TP 5
.B \-p
Checkpoint the database at least every
.I min
minutes.
.TP 5
.B \-v
Write the time of each checkpoint to the standard output.
.PP
At least one of the
.BR \-1 ,
.B \-k
and
.B \-p
options must be specified.
.PP
.Si db_checkpoint
.PP
.Ex db_checkpoint
.SH "ENVIRONMENT VARIABLES"
The following environment variables affect the execution of
.IR db_checkpoint :
.TP 5
.Dh db_checkpoint
.SH "SEE ALSO"
.Gn
.PP
.Sa