| Db::verify |
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#include <db_cxx.h>int Db::verify(const char *file, const char *database, ostream *outfile, u_int32_t flags);
The Db::verify method verifies the integrity of all databases in the file specified by the file parameter, and optionally outputs the databases' key/data pairs to the file stream specified by the outfile parameter.
The Db::verify method does not perform any locking, even in Berkeley DB environments that are configured with a locking subsystem. As such, it should only be used on files that are not being modified by another thread of control.
The Db::verify method may not be called after the Db::open method is called.
The Db handle may not be accessed again after Db::verify is called, regardless of its return.
The Db::verify method will return DB_VERIFY_BAD if a database is corrupted. When the DB_SALVAGE flag is specified, the DB_VERIFY_BAD return means that all key/data pairs in the file may not have been successfully output. Unless otherwise specified, the Db::verify method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, and returns 0 on success.
ParametersThe database parameter must be set to NULL except when the DB_ORDERCHKONLY flag is set.
The output format is the same as that specified for the db_dump utility, and can be used as input for the db_load utility.
Because the key/data pairs are output in page order as opposed to the sort order used by db_dump, using Db::verify to dump key/data pairs normally produces less than optimal loads for Btree databases.
In addition, the following flags may be set by bitwise inclusively OR'ing them into the flags parameter:
Note: different systems may have different notions about what characters are considered printing characters, and databases dumped in this manner may be less portable to external systems.
The Db::verify method normally verifies that btree keys and duplicate items are correctly sorted, and hash keys are correctly hashed. If the file being verified contains multiple databases using differing sorting or hashing algorithms, some of them must necessarily fail database verification because only one sort order or hash function can be specified before Db::verify is called. To verify files with multiple databases having differing sorting orders or hashing functions, first perform verification of the file as a whole by using the DB_NOORDERCHK flag, and then individually verify the sort order and hashing function for each database in the file using the DB_ORDERCHKONLY flag.
When this flag is specified, a database parameter should also be specified, indicating the database in the physical file which is to be checked. This flag is only safe to use on databases that have already successfully been verified using Db::verify with the DB_NOORDERCHK flag set.
If the database was opened within a database environment, the environment variable DB_HOME may be used as the path of the database environment home.
Db::verify is affected by any database directory specified using the DbEnv::set_data_dir method, or by setting the "set_data_dir" string in the environment's DB_CONFIG file.
The Db::verify method may fail and throw DbException, encapsulating one of the following non-zero errors, or return one of the following non-zero errors:
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