1 | /***************************************************************************** |
2 | |
3 | Copyright (c) 2006, 2016, Oracle and/or its affiliates. All Rights Reserved. |
4 | |
5 | This program is free software; you can redistribute it and/or modify it under |
6 | the terms of the GNU General Public License as published by the Free Software |
7 | Foundation; version 2 of the License. |
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9 | This program is distributed in the hope that it will be useful, but WITHOUT |
10 | ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS |
11 | FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. |
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13 | You should have received a copy of the GNU General Public License along with |
14 | this program; if not, write to the Free Software Foundation, Inc., |
15 | 51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA |
16 | |
17 | *****************************************************************************/ |
18 | |
19 | /**************************************************//** |
20 | @file row/row0ext.cc |
21 | Caching of externally stored column prefixes |
22 | |
23 | Created September 2006 Marko Makela |
24 | *******************************************************/ |
25 | |
26 | #include "row0ext.h" |
27 | #include "btr0cur.h" |
28 | |
29 | /** Fills the column prefix cache of an externally stored column. |
30 | @param[in,out] ext column prefix cache |
31 | @param[in] i index of ext->ext[] |
32 | @param[in] page_size page size |
33 | @param[in] dfield data field */ |
34 | static |
35 | void |
36 | row_ext_cache_fill( |
37 | row_ext_t* ext, |
38 | ulint i, |
39 | const page_size_t& page_size, |
40 | const dfield_t* dfield) |
41 | { |
42 | const byte* field = static_cast<const byte*>( |
43 | dfield_get_data(dfield)); |
44 | ulint f_len = dfield_get_len(dfield); |
45 | byte* buf = ext->buf + i * ext->max_len; |
46 | |
47 | ut_ad(ext->max_len > 0); |
48 | ut_ad(i < ext->n_ext); |
49 | ut_ad(dfield_is_ext(dfield)); |
50 | ut_a(f_len >= BTR_EXTERN_FIELD_REF_SIZE); |
51 | |
52 | if (UNIV_UNLIKELY(!memcmp(field_ref_zero, |
53 | field + f_len - BTR_EXTERN_FIELD_REF_SIZE, |
54 | BTR_EXTERN_FIELD_REF_SIZE))) { |
55 | /* The BLOB pointer is not set: we cannot fetch it */ |
56 | ext->len[i] = 0; |
57 | } else { |
58 | if (ext->max_len == REC_VERSION_56_MAX_INDEX_COL_LEN |
59 | && f_len > BTR_EXTERN_FIELD_REF_SIZE) { |
60 | /* In this case, the field is in B format or beyond, |
61 | (refer to the definition of row_ext_t.max_len) |
62 | and the field is already fill with prefix, otherwise |
63 | f_len would be BTR_EXTERN_FIELD_REF_SIZE. |
64 | So there is no need to re-read the prefix externally, |
65 | but just copy the local prefix to buf. Please note |
66 | if the ext->len[i] is zero, it means an error |
67 | as above. */ |
68 | memcpy(buf, field, f_len - BTR_EXTERN_FIELD_REF_SIZE); |
69 | ext->len[i] = f_len - BTR_EXTERN_FIELD_REF_SIZE; |
70 | } else { |
71 | /* Fetch at most ext->max_len of the column. |
72 | The column should be non-empty. However, |
73 | trx_rollback_all_recovered() may try to |
74 | access a half-deleted BLOB if the server previously |
75 | crashed during the execution of |
76 | btr_free_externally_stored_field(). */ |
77 | ext->len[i] = btr_copy_externally_stored_field_prefix( |
78 | buf, ext->max_len, page_size, field, f_len); |
79 | } |
80 | } |
81 | } |
82 | |
83 | /********************************************************************//** |
84 | Creates a cache of column prefixes of externally stored columns. |
85 | @return own: column prefix cache */ |
86 | row_ext_t* |
87 | row_ext_create( |
88 | /*===========*/ |
89 | ulint n_ext, /*!< in: number of externally stored columns */ |
90 | const ulint* ext, /*!< in: col_no's of externally stored columns |
91 | in the InnoDB table object, as reported by |
92 | dict_col_get_no(); NOT relative to the records |
93 | in the clustered index */ |
94 | ulint flags, /*!< in: table->flags */ |
95 | const dtuple_t* tuple, /*!< in: data tuple containing the field |
96 | references of the externally stored |
97 | columns; must be indexed by col_no; |
98 | the clustered index record must be |
99 | covered by a lock or a page latch |
100 | to prevent deletion (rollback or purge). */ |
101 | mem_heap_t* heap) /*!< in: heap where created */ |
102 | { |
103 | ulint i; |
104 | const page_size_t& page_size = dict_tf_get_page_size(flags); |
105 | |
106 | row_ext_t* ret; |
107 | |
108 | ut_ad(n_ext > 0); |
109 | |
110 | ret = static_cast<row_ext_t*>( |
111 | mem_heap_alloc(heap, |
112 | (sizeof *ret) + (n_ext - 1) * sizeof ret->len)); |
113 | |
114 | ret->n_ext = n_ext; |
115 | ret->ext = ext; |
116 | ret->max_len = DICT_MAX_FIELD_LEN_BY_FORMAT_FLAG(flags); |
117 | ret->page_size.copy_from(page_size); |
118 | |
119 | ret->buf = static_cast<byte*>( |
120 | mem_heap_alloc(heap, n_ext * ret->max_len)); |
121 | |
122 | #ifdef UNIV_DEBUG |
123 | memset(ret->buf, 0xaa, n_ext * ret->max_len); |
124 | UNIV_MEM_ALLOC(ret->buf, n_ext * ret->max_len); |
125 | #endif |
126 | |
127 | /* Fetch the BLOB prefixes */ |
128 | for (i = 0; i < n_ext; i++) { |
129 | const dfield_t* dfield; |
130 | |
131 | dfield = dtuple_get_nth_field(tuple, ext[i]); |
132 | row_ext_cache_fill(ret, i, page_size, dfield); |
133 | } |
134 | |
135 | return(ret); |
136 | } |
137 | |