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/*****************************************************************************
Copyright (c) 2006, 2016, Oracle and/or its affiliates. All Rights Reserved.
Copyright (c) 2019, MariaDB Corporation.
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 Street, Fifth Floor, Boston, MA 02110-1335 USA
*****************************************************************************/
/**************************************************//**
@file row/row0ext.cc
Caching of externally stored column prefixes
Created September 2006 Marko Makela
*******************************************************/
#include "row0ext.h"
#include "btr0cur.h"
/** Fills the column prefix cache of an externally stored column.
@param[in,out] ext column prefix cache
@param[in] i index of ext->ext[]
@param[in] space tablespace
@param[in] dfield data field */
static
void
row_ext_cache_fill(
row_ext_t* ext,
ulint i,
fil_space_t* space,
const dfield_t* dfield)
{
const byte* field = static_cast<const byte*>(
dfield_get_data(dfield));
ulint f_len = dfield_get_len(dfield);
byte* buf = ext->buf + i * ext->max_len;
ut_ad(ext->max_len > 0);
ut_ad(i < ext->n_ext);
ut_ad(dfield_is_ext(dfield));
ut_a(f_len >= BTR_EXTERN_FIELD_REF_SIZE);
if (UNIV_UNLIKELY(!memcmp(field_ref_zero,
field + f_len - BTR_EXTERN_FIELD_REF_SIZE,
BTR_EXTERN_FIELD_REF_SIZE))) {
/* The BLOB pointer is not set: we cannot fetch it */
ext->len[i] = 0;
} else {
if (ext->max_len == REC_VERSION_56_MAX_INDEX_COL_LEN
&& f_len > BTR_EXTERN_FIELD_REF_SIZE) {
/* In this case, the field is in B format or beyond,
(refer to the definition of row_ext_t.max_len)
and the field is already fill with prefix, otherwise
f_len would be BTR_EXTERN_FIELD_REF_SIZE.
So there is no need to re-read the prefix externally,
but just copy the local prefix to buf. Please note
if the ext->len[i] is zero, it means an error
as above. */
memcpy(buf, field, f_len - BTR_EXTERN_FIELD_REF_SIZE);
ext->len[i] = f_len - BTR_EXTERN_FIELD_REF_SIZE;
} else {
/* Fetch at most ext->max_len of the column.
The column should be non-empty. However,
trx_rollback_all_recovered() may try to
access a half-deleted BLOB if the server previously
crashed during the execution of
btr_free_externally_stored_field(). */
ext->len[i] = btr_copy_externally_stored_field_prefix(
buf, ext->max_len, ext->zip_size,
field, f_len);
}
}
}
/********************************************************************//**
Creates a cache of column prefixes of externally stored columns.
@return own: column prefix cache */
row_ext_t*
row_ext_create(
/*===========*/
ulint n_ext, /*!< in: number of externally stored columns */
const ulint* ext, /*!< in: col_no's of externally stored columns
in the InnoDB table object, as reported by
dict_col_get_no(); NOT relative to the records
in the clustered index */
const dict_table_t& table, /*!< in: table */
const dtuple_t* tuple, /*!< in: data tuple containing the field
references of the externally stored
columns; must be indexed by col_no;
the clustered index record must be
covered by a lock or a page latch
to prevent deletion (rollback or purge). */
mem_heap_t* heap) /*!< in: heap where created */
{
if (!table.space) {
return NULL;
}
ut_ad(n_ext > 0);
row_ext_t* ret = static_cast<row_ext_t*>(
mem_heap_alloc(heap,
(sizeof *ret) + (n_ext - 1) * sizeof ret->len));
ret->n_ext = n_ext;
ret->ext = ext;
ret->max_len = DICT_MAX_FIELD_LEN_BY_FORMAT_FLAG(table.flags);
ret->zip_size = dict_tf_get_zip_size(table.flags);
ret->buf = static_cast<byte*>(
mem_heap_alloc(heap, n_ext * ret->max_len));
/* Fetch the BLOB prefixes */
for (ulint i = 0; i < n_ext; i++) {
const dfield_t* dfield;
dfield = dtuple_get_nth_field(tuple, ext[i]);
row_ext_cache_fill(ret, i, table.space, dfield);
}
return(ret);
}
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