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/*****************************************************************************
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 ext->max_len */
{
ut_ad(ext);
ut_ad(len);
ut_ad(i < ext->n_ext);
*len = ext->len[i];
ut_ad(*len <= ext->max_len);
ut_ad(ext->max_len > 0);
if (UNIV_UNLIKELY(*len == 0)) {
/* The BLOB could not be fetched to the cache. */
return(field_ref_zero);
} else {
return(ext->buf + i * ext->max_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 ext->max_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);
}
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