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132 lines
4.4 KiB
C++
132 lines
4.4 KiB
C++
/*****************************************************************************
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Copyright (c) 2006, 2016, Oracle and/or its affiliates. All Rights Reserved.
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Copyright (c) 2019, 2020, MariaDB Corporation.
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This program is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free Software
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Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along with
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this program; if not, write to the Free Software Foundation, Inc.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA
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*****************************************************************************/
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/**************************************************//**
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@file row/row0ext.cc
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Caching of externally stored column prefixes
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Created September 2006 Marko Makela
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*******************************************************/
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#include "row0ext.h"
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#include "btr0cur.h"
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/** Fills the column prefix cache of an externally stored column.
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@param[in,out] ext column prefix cache
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@param[in] i index of ext->ext[]
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@param[in] space tablespace
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@param[in] dfield data field */
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static
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void
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row_ext_cache_fill(
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row_ext_t* ext,
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ulint i,
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fil_space_t* space,
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const dfield_t* dfield)
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{
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const byte* field = static_cast<const byte*>(
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dfield_get_data(dfield));
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ulint f_len = dfield_get_len(dfield);
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byte* buf = ext->buf + i * ext->max_len;
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ut_ad(ext->max_len > 0);
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ut_ad(i < ext->n_ext);
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ut_ad(dfield_is_ext(dfield));
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ut_a(f_len >= BTR_EXTERN_FIELD_REF_SIZE);
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if (UNIV_UNLIKELY(!memcmp(field_ref_zero,
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field + f_len - BTR_EXTERN_FIELD_REF_SIZE,
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BTR_EXTERN_FIELD_REF_SIZE))) {
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/* The BLOB pointer is not set: we cannot fetch it */
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ext->len[i] = 0;
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} else {
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if (ext->max_len == REC_VERSION_56_MAX_INDEX_COL_LEN
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&& f_len > BTR_EXTERN_FIELD_REF_SIZE) {
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/* In this case, the field is in B format or beyond,
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(refer to the definition of row_ext_t.max_len)
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and the field is already fill with prefix, otherwise
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f_len would be BTR_EXTERN_FIELD_REF_SIZE.
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So there is no need to re-read the prefix externally,
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but just copy the local prefix to buf. Please note
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if the ext->len[i] is zero, it means an error
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as above. */
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memcpy(buf, field, f_len - BTR_EXTERN_FIELD_REF_SIZE);
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ext->len[i] = f_len - BTR_EXTERN_FIELD_REF_SIZE;
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} else {
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/* Fetch at most ext->max_len of the column.
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The column should be non-empty. However,
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trx_rollback_all_recovered() may try to
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access a half-deleted BLOB if the server previously
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crashed during the execution of
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btr_free_externally_stored_field(). */
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ext->len[i] = btr_copy_externally_stored_field_prefix(
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buf, ext->max_len, ext->zip_size,
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field, f_len);
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}
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}
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}
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/********************************************************************//**
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Creates a cache of column prefixes of externally stored columns.
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@return own: column prefix cache */
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row_ext_t*
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row_ext_create(
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/*===========*/
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ulint n_ext, /*!< in: number of externally stored columns */
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const ulint* ext, /*!< in: col_no's of externally stored columns
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in the InnoDB table object, as reported by
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dict_col_get_no(); NOT relative to the records
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in the clustered index */
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const dict_table_t& table, /*!< in: table */
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const dtuple_t* tuple, /*!< in: data tuple containing the field
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references of the externally stored
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columns; must be indexed by col_no;
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the clustered index record must be
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covered by a lock or a page latch
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to prevent deletion (rollback or purge). */
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mem_heap_t* heap) /*!< in: heap where created */
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{
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if (!table.space) {
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return NULL;
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}
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ut_ad(n_ext > 0);
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row_ext_t* ret = static_cast<row_ext_t*>(
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mem_heap_alloc(heap,
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(sizeof *ret) + (n_ext - 1) * sizeof ret->len));
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ret->n_ext = n_ext;
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ret->ext = ext;
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ret->max_len = DICT_MAX_FIELD_LEN_BY_FORMAT_FLAG(table.flags);
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ret->zip_size = dict_tf_get_zip_size(table.flags);
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ret->buf = static_cast<byte*>(
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mem_heap_alloc(heap, n_ext * ret->max_len));
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/* Fetch the BLOB prefixes */
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for (ulint i = 0; i < n_ext; i++) {
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const dfield_t* dfield;
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dfield = dtuple_get_nth_field(tuple, ext[i]);
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row_ext_cache_fill(ret, i, table.space, dfield);
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}
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return(ret);
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}
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