n.html">Db::open was called.

The specified cache size was impossibly small.

The Db::set_cachesize method may fail and throw an exception or return a non-zero error for errors specified for other Berkeley DB and C library or system methods. If a catastrophic error has occurred, the Db::set_cachesize method may fail and either return DB_RUNRECOVERY or throw an exception encapsulating DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail in the same way.

Class

Db

See Also

Db::associate, Db::close, Db::cursor, Db::del, Db::err, Db::errx Db::fd, Db::get, Db::pget, Db::get_byteswapped, Db::get_type, Db::join, Db::key_range, Db::open, Db::put, Db::remove, Db::rename, Db::set_alloc, Db::set_append_recno, Db::set_bt_compare, Db::set_bt_minkey, Db::set_bt_prefix, Db::set_cachesize, Db::set_dup_compare, Db::set_errcall, Db::set_errfile, Db::set_errpfx, Db::set_feedback, Db::set_flags, Db::set_h_ffactor, Db::set_h_hash, Db::set_h_nelem, Db::set_lorder, Db::set_pagesize, Db::set_paniccall, Db::set_q_extentsize, Db::set_re_delim, Db::set_re_len, Db::set_re_pad, Db::set_re_source, Db::stat, Db::sync, Db::truncate, Db::upgrade, and Db::verify.

APIRef

Copyright Sleepycat Software Berkeley DB: Db::set_dup_compare

Db::set_dup_compare

 APIRef 

#include <db_cxx.h>


extern "C" {
	typedef int (*dup_compare_fcn_type)(DB *, const DBT *, const DBT *);
};
int
Db::set_dup_compare(dup_compare_fcn_type dup_compare_fcn);

Description

Set the duplicate data item comparison function. The comparison function is called when it is necessary to compare a data item specified by the application with a data item currently stored in the tree. The first argument to the comparison function is the Dbt representing the application's data item; the second is the current tree's data item.

The comparison function must return an integer value less than, equal to, or greater than zero if the first data item argument is considered to be respectively less than, equal to, or greater than the second data item argument. In addition, the comparison function must cause the data items in the set to be well-ordered. The comparison function must correctly handle any data item values used by the application (possibly including zero-length data items). The data and size fields of the Dbt are the only fields that may be used for the purposes of this comparison, and no particular alignment of the memory to which the data field refers may be assumed.

If no comparison function is specified, the data items are compared lexically, with shorter data items collating before longer data items. The same duplicate data item comparison method must be used each time a particular Btree is opened.

The Db::set_dup_compare interface may be used only to configure Berkeley DB before the Db::open interface is called.

The Db::set_dup_compare 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.

Errors

The Db::set_dup_compare method may fail and throw an exception or return a non-zero error for the following conditions:

EINVAL
An invalid flag value or parameter was specified.

The Db::set_dup_compare method may fail and throw an exception or return a non-zero error for errors specified for other Berkeley DB and C library or system methods. If a catastrophic error has occurred, the Db::set_dup_compare method may fail and either return DB_RUNRECOVERY or throw an exception encapsulating DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail in the same way.

Class

Db

See Also

Db::associate, Db::close, Db::cursor, Db::del, Db::err, Db::errx Db::fd, Db::get, Db::pget, Db::get_byteswapped, Db::get_type, Db::join, Db::key_range, Db::open, Db::put, Db::remove, Db::rename, Db::set_alloc, Db::set_append_recno, Db::set_bt_compare, Db::set_bt_minkey, Db::set_bt_prefix, Db::set_cachesize, Db::set_dup_compare, Db::set_errcall, Db::set_errfile, Db::set_errpfx, Db::set_feedback, Db::set_flags, Db::set_h_ffactor, Db::set_h_hash, Db::set_h_nelem, Db::set_lorder, Db::set_pagesize, Db::set_paniccall, Db::set_q_extentsize, Db::set_re_delim, Db::set_re_len, Db::set_re_pad, Db::set_re_source, Db::stat, Db::sync, Db::truncate, Db::upgrade, and Db::verify.

APIRef

Copyright Sleepycat Software Berkeley DB: Db::set_errcall

Db::set_errcall

 APIRef 

#include <db_cxx.h>


void Db::set_errcall(
    void (*db_errcall_fcn)(const char *errpfx, char *msg));

Description

When an error occurs in the Berkeley DB library, an exception is thrown or an error return value is returned by the method. In some cases, however, the errno value may be insufficient to completely describe the cause of the error, especially during initial application debugging.

The DbEnv::set_errcall and Db::set_errcall methods are used to enhance the mechanism for reporting error messages to the application. In some cases, when an error occurs, Berkeley DB will call db_errcall_fcn with additional error information. The function must be defined with two arguments; the first will be the prefix string (as previously set by Db::set_errpfx or DbEnv::set_errpfx); the second will be the error message string. It is up to the db_errcall_fcn method to display the error message in an appropriate manner.

Alternatively, you can use the DbEnv::set_error_stream method to display the additional information via an output stream, or the Db::set_errfile or DbEnv::set_errfile methods to display the additional information via a C library FILE *. You should not mix these approaches.

This error-logging enhancement does not slow performance or significantly increase application size, and may be run during normal operation as well as during application debugging.

For Db handles opened inside of Berkeley DB environments, calling the Db::set_errcall method affects the entire environment and is equivalent to calling the DbEnv::set_errcall method.

The Db::set_errcall interface may be used to configure Berkeley DB at any time during the life of the application.

Class

Db

See Also

Db::associate, Db::close, Db::cursor, Db::del, Db::err, Db::errx Db::fd, Db::get, Db::pget, Db::get_byteswapped, Db::get_type, Db::join, Db::key_range, Db::open, Db::put, Db::remove, Db::rename, Db::set_alloc, Db::set_append_recno, Db::set_bt_compare, Db::set_bt_minkey, Db::set_bt_prefix, Db::set_cachesize, Db::set_dup_compare, Db::set_errcall, Db::set_errfile, Db::set_errpfx, Db::set_feedback, Db::set_flags, Db::set_h_ffactor, Db::set_h_hash, Db::set_h_nelem, Db::set_lorder, Db::set_pagesize, Db::set_paniccall, Db::set_q_extentsize, Db::set_re_delim, Db::set_re_len, Db::set_re_pad, Db::set_re_source, Db::stat, Db::sync, Db::truncate, Db::upgrade, and Db::verify.

APIRef

Copyright Sleepycat Software