~drizzle-trunk/drizzle/development

/*****************************************************************************

Copyright (c) 2006, 2009, Innobase Oy. All Rights Reserved.

This program is free software; you can redistribute it and/or modify it under

the terms of the GNU General Public License as published by the Free Software

Foundation; version 2 of the License.

This program is distributed in the hope that it will be useful, but WITHOUT

ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with

this program; if not, write to the Free Software Foundation, Inc., 51 Franklin

St, Fifth Floor, Boston, MA 02110-1301 USA

*****************************************************************************/

/**************************************************//**

@file include/row0ext.ic

Caching of externally stored column prefixes

Created September 2006 Marko Makela

*******************************************************/

#include "rem0types.h"

#include "btr0types.h"

/********************************************************************//**

Looks up a column prefix of an externally stored column.

@return column prefix, or NULL if the column is not stored externally,

or pointer to field_ref_zero if the BLOB pointer is unset */

UNIV_INLINE

const byte*

row_ext_lookup_ith(

/*===============*/

	const row_ext_t*	ext,	/*!< in/out: column prefix cache */

	ulint			i,	/*!< in: index of ext->ext[] */

	ulint*			len)	/*!< out: length of prefix, in bytes,

					at most REC_MAX_INDEX_COL_LEN */

{

	ut_ad(ext);

	ut_ad(len);

	ut_ad(i < ext->n_ext);

	*len = ext->len[i];

	if (UNIV_UNLIKELY(*len == 0)) {

		/* The BLOB could not be fetched to the cache. */

		return(field_ref_zero);

	} else {

		return(ext->buf + i * REC_MAX_INDEX_COL_LEN);

	}

}

/********************************************************************//**

Looks up a column prefix of an externally stored column.

@return column prefix, or NULL if the column is not stored externally,

or pointer to field_ref_zero if the BLOB pointer is unset */

UNIV_INLINE

const byte*

row_ext_lookup(

/*===========*/

	const row_ext_t*	ext,	/*!< in: column prefix cache */

	ulint			col,	/*!< in: column number in the InnoDB

					table object, as reported by

					dict_col_get_no(); NOT relative to the

					records in the clustered index */

	ulint*			len)	/*!< out: length of prefix, in bytes,

					at most REC_MAX_INDEX_COL_LEN */

{

	ulint	i;

	ut_ad(ext);

	ut_ad(len);

	for (i = 0; i < ext->n_ext; i++) {

		if (col == ext->ext[i]) {

			return(row_ext_lookup_ith(ext, i, len));

		}

	}

	return(NULL);

}