1<!--$Id: log_archive.so,v 10.49 2004/08/13 03:38:57 bostic Exp $--> 2<!--Copyright (c) 1997,2008 Oracle. All rights reserved.--> 3<!--See the file LICENSE for redistribution information.--> 4<html> 5<head> 6<title>Berkeley DB: DB_ENV->log_archive</title> 7<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> 8<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++"> 9</head> 10<body bgcolor=white> 11<table width="100%"><tr valign=top> 12<td> 13<b>DB_ENV->log_archive</b> 14</td> 15<td align=right> 16<a href="/api_c/api_core.html"><img src="/images/api.gif" alt="API"></a> 17<a href="/ref/toc.html"><img src="/images/ref.gif" alt="Ref"></a></td> 18</tr></table> 19<hr size=1 noshade> 20<tt> 21<b><pre> 22#include <db.h> 23<p> 24int 25DB_ENV->log_archive(DB_ENV *env, char *(*listp)[], u_int32_t flags); 26</pre></b> 27<hr size=1 noshade> 28<b>Description: DB_ENV->log_archive</b> 29<p>The DB_ENV->log_archive method returns an array of log or database filenames.</p> 30<p>By default, DB_ENV->log_archive returns the names of all of the log 31files that are no longer in use (for example, that are no longer 32involved in active transactions), and that may safely be archived for 33catastrophic recovery and then removed from the system. If there are 34no filenames to return, the memory location to which <b>listp</b> 35refers will be set to NULL.</p> 36<p>Arrays of log filenames are stored in allocated memory. If application-specific allocation 37routines have been declared (see <a href="/api_c/env_set_alloc.html">DB_ENV->set_alloc</a> for more 38information), they are used to allocate the memory; otherwise, the 39standard C library <b>malloc</b>(3) is used. The caller is 40responsible for deallocating the memory. To deallocate the memory, free 41the memory reference; references inside the returned memory need not be 42individually freed.</p> 43<p>Log cursor handles (returned by the <a href="/api_c/log_cursor.html">DB_ENV->log_cursor</a> method) may have open 44file descriptors for log files in the database environment. Also, the 45Berkeley DB interfaces to the database environment logging subsystem (for 46example, <a href="/api_c/log_put.html">DB_ENV->log_put</a> and <a href="/api_c/txn_abort.html">DB_TXN->abort</a>) may allocate log cursors 47and have open file descriptors for log files as well. On operating 48systems where filesystem related system calls (for example, rename and 49unlink on Windows/NT) can fail if a process has an open file descriptor 50for the affected file, attempting to move or remove the log files listed 51by DB_ENV->log_archive may fail. All Berkeley DB internal use of log cursors 52operates on active log files only and furthermore, is short-lived in 53nature. So, an application seeing such a failure should be restructured 54to close any open log cursors it may have, and otherwise to retry the 55operation until it succeeds. (Although the latter is not likely to be 56necessary; it is hard to imagine a reason to move or rename a log file 57in which transactions are being logged or aborted.)</p> 58<p>See <a href="/utility/db_archive.html">db_archive</a> for more information on database archival 59procedures.</p> 60<p>The DB_ENV->log_archive method is the underlying method used by the <a href="/utility/db_archive.html">db_archive</a> utility. 61See the <a href="/utility/db_archive.html">db_archive</a> utility source code for an example of using DB_ENV->log_archive 62in a IEEE/ANSI Std 1003.1 (POSIX) environment.</p> 63<p>The DB_ENV->log_archive method 64returns a non-zero error value on failure 65and 0 on success. 66</p> 67<b>Parameters</b> <br> 68 <b>flags</b><ul compact><li>The <b>flags</b> parameter must be set to 0 or by bitwise inclusively <b>OR</b>'ing together one 69or more of the following values: 70<br> 71<b><a name="DB_ARCH_ABS">DB_ARCH_ABS</a></b><ul compact><li>All pathnames are returned as absolute pathnames, instead of relative 72to the database home directory.</ul> 73<b><a name="DB_ARCH_DATA">DB_ARCH_DATA</a></b><ul compact><li>Return the database files that need to be archived in order to recover 74the database from catastrophic failure. If any of the database files 75have not been accessed during the lifetime of the current log files, 76DB_ENV->log_archive will not include them in this list. It is also 77possible that some of the files referred to by the log have since been 78deleted from the system. 79<p>The DB_ARCH_DATA and DB_ARCH_LOG flags are mutually exclusive.</p></ul> 80<b><a name="DB_ARCH_LOG">DB_ARCH_LOG</a></b><ul compact><li>Return all the log filenames, regardless of whether or not they are in 81use. 82<p>The DB_ARCH_DATA and DB_ARCH_LOG flags are mutually exclusive.</p></ul> 83<b><a name="DB_ARCH_REMOVE">DB_ARCH_REMOVE</a></b><ul compact><li>Remove log files that are no longer needed; no filenames are returned. 84Automatic log file removal is likely to make catastrophic recovery 85impossible. 86<p>The DB_ARCH_REMOVE flag may not be specified with any other 87flag.</p></ul> 88<br></ul> 89 <b>listp</b><ul compact><li>The <b>listp</b> parameter references memory into which the allocated 90array of log or database filenames is copied. If there are no filenames 91to return, the memory location to which <b>listp</b> refers will be set 92to NULL.</ul> 93<br> 94<br><b>Errors</b> 95<p>The DB_ENV->log_archive method 96may fail and return one of the following non-zero errors:</p> 97<br> 98<b>EINVAL</b><ul compact><li>An 99invalid flag value or parameter was specified.</ul> 100<br> 101<hr size=1 noshade> 102<br><b>Class</b> 103<a href="/api_c/env_class.html">DB_ENV</a>, <a href="/api_c/logc_class.html">DB_LOGC</a>, <a href="/api_c/lsn_class.html">DB_LSN</a> 104<br><b>See Also</b> 105<a href="/api_c/log_list.html">Logging Subsystem and Related Methods</a> 106</tt> 107<table width="100%"><tr><td><br></td><td align=right> 108<a href="/api_c/api_core.html"><img src="/images/api.gif" alt="API"></a><a href="/ref/toc.html"><img src="/images/ref.gif" alt="Ref"></a> 109</td></tr></table> 110<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font> 111</body> 112</html> 113
