1<!--$Id: db_verify.so,v 10.30 2005/03/08 16:29:34 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::verify</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::verify</b> 14</td> 15<td align=right> 16<a href="../api_cxx/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_cxx.h> 23<p> 24int 25Db::verify(const char *file, 26 const char *database, ostream *outfile, u_int32_t flags); 27</pre></b> 28<hr size=1 noshade> 29<b>Description: Db::verify</b> 30<p>The Db::verify method verifies the integrity of all databases in the 31file specified by the <b>file</b> parameter, and optionally outputs the 32databases' key/data pairs to the file stream specified by the 33<b>outfile</b> parameter.</p> 34<p><b>The Db::verify method does not perform any locking, even in Berkeley DB 35environments that are configured with a locking subsystem. As such, it 36should only be used on files that are not being modified by another 37thread of control.</b></p> 38<p>The Db::verify method may not be called after the <a href="../api_cxx/db_open.html">Db::open</a> method is called. 39</p> 40<p>The <a href="../api_cxx/db_class.html">Db</a> handle may not be accessed again after Db::verify is 41called, regardless of its return.</p> 42<a name="2"><!--meow--></a> 43<p>The Db::verify method will return DB_VERIFY_BAD if a database is 44corrupted. When the DB_SALVAGE flag is specified, the 45DB_VERIFY_BAD return means that all key/data pairs in the file 46may not have been successfully output. 47Unless otherwise specified, the Db::verify method 48either returns a non-zero error value 49or throws an exception that encapsulates a non-zero error value on 50failure, and returns 0 on success. 51</p> 52<b>Parameters</b> <br> 53 <b>database</b><ul compact><li>The <b>database</b> parameter is the database in <b>file</b> on which 54the database checks for btree and duplicate sort order and for hashing 55are to be performed. See the DB_ORDERCHKONLY flag for more 56information. 57<p>The database parameter must be set to NULL except when the 58DB_ORDERCHKONLY flag is set.</p></ul> 59 <b>file</b><ul compact><li>The <b>file</b> parameter is the physical file in which the databases 60to be verified are found.</ul> 61 <b>flags</b><ul compact><li>The <b>flags</b> parameter must be set to 0 or 62the following value: 63<br> 64<b><a name="DB_SALVAGE">DB_SALVAGE</a></b><ul compact><li>Write the key/data pairs from all databases in the file to the file 65stream named in the <b>outfile</b> parameter. Key values are written 66for Btree, Hash and Queue databases, but not for Recno databases. 67<p>The output format is the same as that specified for the <a href="../utility/db_dump.html">db_dump</a> 68utility, and can be used as input for the <a href="../utility/db_load.html">db_load</a> utility.</p> 69<p>Because the key/data pairs are output in page order as opposed to the sort 70order used by <a href="../utility/db_dump.html">db_dump</a>, using Db::verify to dump key/data 71pairs normally produces less than optimal loads for Btree databases.</p></ul> 72<br> 73<p>In addition, the following flags may be set by bitwise inclusively <b>OR</b>'ing them into the 74<b>flags</b> parameter:</p> 75<br> 76<b><a name="DB_AGGRESSIVE">DB_AGGRESSIVE</a></b><ul compact><li>Output <b>all</b> the key/data pairs in the file that can be found. 77By default, Db::verify does not assume corruption. For example, 78if a key/data pair on a page is marked as deleted, it is not then written 79to the output file. When DB_AGGRESSIVE is specified, corruption 80is assumed, and any key/data pair that can be found is written. In this 81case, key/data pairs that are corrupted or have been deleted may appear 82in the output (even if the file being salvaged is in no way corrupt), and 83the output will almost certainly require editing before being loaded into 84a database.</ul> 85<b><a name="DB_PRINTABLE">DB_PRINTABLE</a></b><ul compact><li>When using the DB_SALVAGE flag, if characters in either the key 86or data items are printing characters (as defined by <b>isprint</b>(3)), use printing characters to represent them. This flag permits users 87to use standard text editors and tools to modify the contents of 88databases or selectively remove data from salvager output. 89<p>Note: different systems may have different notions about what characters 90are considered <i>printing characters</i>, and databases dumped in 91this manner may be less portable to external systems.</p></ul> 92<b><a name="DB_NOORDERCHK">DB_NOORDERCHK</a></b><ul compact><li>Skip the database checks for btree and duplicate sort order and for 93hashing. 94<p>The Db::verify method normally verifies that btree keys and duplicate 95items are correctly sorted, and hash keys are correctly hashed. If the 96file being verified contains multiple databases using differing sorting 97or hashing algorithms, some of them must necessarily fail database 98verification because only one sort order or hash function can be 99specified before Db::verify is called. To verify files with 100multiple databases having differing sorting orders or hashing functions, 101first perform verification of the file as a whole by using the 102DB_NOORDERCHK flag, and then individually verify the sort order 103and hashing function for each database in the file using the 104DB_ORDERCHKONLY flag.</p></ul> 105<b><a name="DB_ORDERCHKONLY">DB_ORDERCHKONLY</a></b><ul compact><li>Perform the database checks for btree and duplicate sort order and for 106hashing, skipped by DB_NOORDERCHK. 107<p>When this flag is specified, a <b>database</b> parameter should also be 108specified, indicating the database in the physical file which is to be 109checked. This flag is only safe to use on databases that have already 110successfully been verified using Db::verify with the 111DB_NOORDERCHK flag set.</p></ul> 112<br></ul> 113 <b>outfile</b><ul compact><li>The <b>outfile</b> parameter is an optional file stream to which the 114databases' key/data pairs are written.</ul> 115<br> 116<br><b>Environment Variables</b> 117<p>If the database was opened within a database environment, the 118environment variable <b>DB_HOME</b> may be used as the path of the 119database environment home.</p> 120<p>Db::verify is affected by any database directory specified using 121the <a href="../api_cxx/env_set_data_dir.html">DbEnv::set_data_dir</a> method, or by setting the "set_data_dir" string 122in the environment's <a href="../ref/env/db_config.html#DB_CONFIG">DB_CONFIG</a> file.</p> 123<br><b>Errors</b> 124<br> 125<b>ENOENT</b><ul compact><li>The file or directory does not exist.</ul> 126<br> 127<p>The Db::verify method 128may fail and throw 129<a href="../api_cxx/except_class.html">DbException</a>, 130encapsulating one of the following non-zero errors, or return one of 131the following non-zero errors:</p> 132<br> 133<b>EINVAL</b><ul compact><li>If Db::verify was called after <a href="../api_cxx/db_open.html">Db::open</a>; or if an 134invalid flag value or parameter was specified.</ul> 135<br> 136<hr size=1 noshade> 137<br><b>Class</b> 138<a href="../api_cxx/db_class.html">Db</a> 139<br><b>See Also</b> 140<a href="../api_cxx/db_list.html">Databases and Related Methods</a> 141</tt> 142<table width="100%"><tr><td><br></td><td align=right> 143<a href="../api_cxx/api_core.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a> 144</td></tr></table> 145<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font> 146</body> 147</html> 148