MySQL 8.0.30
Source Code Documentation
cmp_varlen_keys.h
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22
23#ifndef CMP_VARLEN_KEYS_INCLUDED
24#define CMP_VARLEN_KEYS_INCLUDED
25
26#include <assert.h>
27#include <stdio.h>
28#include <functional>
29
30#include "sql/sort_param.h"
31#include "sql/sql_array.h"
32
33/**
34 A compare function for variable-length keys used by filesort().
35 For record format documentation, @see Sort_param.
36
37 @param sort_field_array array of field descriptors for sorting
38 @param use_hash compare hash values (for grouping of JSON data)
39 @param s1 pointer to record 1
40 @param s2 pointer to record 2
41 @return true/false according to sorting order
42 true : s1 < s2
43 false : s1 >= s2
44 */
45inline bool cmp_varlen_keys(
46 Bounds_checked_array<st_sort_field> sort_field_array, bool use_hash,
47 const uchar *s1, const uchar *s2) {
50 int res;
51 for (const st_sort_field &sort_field : sort_field_array) {
52 uint kp1_len, kp2_len, kp_len;
53 if (sort_field.maybe_null) {
54 const int k1_nullbyte = *kp1++;
55 const int k2_nullbyte = *kp2++;
56 if (k1_nullbyte != k2_nullbyte) return k1_nullbyte < k2_nullbyte;
57 if (k1_nullbyte == 0 || k1_nullbyte == 0xff) {
58 if (!sort_field.is_varlen) {
59 kp1 += sort_field.length;
60 kp2 += sort_field.length;
61 }
62 continue; // Both key parts are null, nothing to compare
63 }
64 }
65 if (sort_field.is_varlen) {
66 assert(uint4korr(kp1) >= 4);
67 assert(uint4korr(kp2) >= 4);
68
69 kp1_len = uint4korr(kp1) - 4;
70 kp1 += 4;
71
72 kp2_len = uint4korr(kp2) - 4;
73 kp2 += 4;
74
75 kp_len = std::min(kp1_len, kp2_len);
76 } else {
77 kp_len = kp1_len = kp2_len = sort_field.length;
78 }
79
80 res = memcmp(kp1, kp2, kp_len);
81
82 if (res) return res < 0;
83 if (kp1_len != kp2_len) {
84 if (sort_field.reverse)
85 return kp2_len < kp1_len;
86 else
87 return kp1_len < kp2_len;
88 }
89
90 kp1 += kp1_len;
91 kp2 += kp2_len;
92 }
93
94 if (use_hash) {
95 // Compare hashes at the end of sort keys
96 return memcmp(kp1, kp2, 8) < 0;
97 } else {
98 return false;
99 }
100}
101
102/**
103 This struct is used for merging chunks for filesort()
104 For filesort() with fixed-size keys we use memcmp to compare rows.
105 For variable length keys, we use cmp_varlen_keys to compare rows.
106 */
108 size_t m_len;
110
111 // CTOR for filesort() with fixed-size keys
112 explicit Merge_chunk_greater(size_t len) : m_len(len), m_param(nullptr) {}
113
114 // CTOR for filesort() with varlen keys
115 explicit Merge_chunk_greater(Sort_param *param) : m_len(0), m_param(param) {}
116
117 bool operator()(Merge_chunk *a, Merge_chunk *b) const {
119 }
120
122 // Fixed len keys
123 if (m_len) return memcmp(key1, key2, m_len) > 0;
124
125 if (m_param)
127 key1);
128
129 // We can actually have zero-length sort key for filesort().
130 return false;
131 }
132};
133
134#endif // CMP_VARLEN_KEYS_INCLUDED
A wrapper class which provides array bounds checking.
Definition: sql_array.h:46
There are several record formats for sorting:
Definition: sort_param.h:301
Bounds_checked_array< st_sort_field > local_sortorder
ORDER BY list with some precalculated info for filesort.
Definition: sort_param.h:322
static const uint size_of_varlength_field
Definition: sort_param.h:466
bool use_hash
Definition: sort_param.h:310
bool cmp_varlen_keys(Bounds_checked_array< st_sort_field > sort_field_array, bool use_hash, const uchar *s1, const uchar *s2)
A compare function for variable-length keys used by filesort().
Definition: cmp_varlen_keys.h:45
Fido Client Authentication nullptr
Definition: fido_client_plugin.cc:221
static uint16 key1[1001]
Definition: hp_test2.cc:46
static uchar key2[100]
Definition: mi_test2.cc:58
uint32 uint4korr(const char *pT)
Definition: my_byteorder.h:144
unsigned char uchar
Definition: my_inttypes.h:51
This struct is used for merging chunks for filesort() For filesort() with fixed-size keys we use memc...
Definition: cmp_varlen_keys.h:107
Merge_chunk_greater(Sort_param *param)
Definition: cmp_varlen_keys.h:115
bool key_is_greater_than(uchar *key1, uchar *key2) const
Definition: cmp_varlen_keys.h:121
Sort_param * m_param
Definition: cmp_varlen_keys.h:109
bool operator()(Merge_chunk *a, Merge_chunk *b) const
Definition: cmp_varlen_keys.h:117
size_t m_len
Definition: cmp_varlen_keys.h:108
Merge_chunk_greater(size_t len)
Definition: cmp_varlen_keys.h:112
Descriptor for a merge chunk to be sort-merged.
Definition: sql_sort.h:56
uchar * current_key() const
Definition: sql_sort.h:81
Struct that holds information about a sort field.
Definition: sort_param.h:85
unsigned int uint
Definition: uca-dump.cc:29