MySQL 8.4.3
Source Code Documentation
cmp_varlen_keys.h
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23
24#ifndef CMP_VARLEN_KEYS_INCLUDED
25#define CMP_VARLEN_KEYS_INCLUDED
26
27#include <assert.h>
28#include <stdio.h>
29#include <functional>
30
31#include "sql/sort_param.h"
32#include "sql/sql_array.h"
33
34/**
35 A compare function for variable-length keys used by filesort().
36 For record format documentation, @see Sort_param.
37
38 @param sort_field_array array of field descriptors for sorting
39 @param use_hash compare hash values (for grouping of JSON data)
40 @param s1 pointer to record 1
41 @param s2 pointer to record 2
42 @return true/false according to sorting order
43 true : s1 < s2
44 false : s1 >= s2
45 */
46inline bool cmp_varlen_keys(
47 Bounds_checked_array<st_sort_field> sort_field_array, bool use_hash,
48 const uchar *s1, const uchar *s2) {
51 int res;
52 for (const st_sort_field &sort_field : sort_field_array) {
53 uint kp1_len, kp2_len, kp_len;
54 if (sort_field.maybe_null) {
55 const int k1_nullbyte = *kp1++;
56 const int k2_nullbyte = *kp2++;
57 if (k1_nullbyte != k2_nullbyte) return k1_nullbyte < k2_nullbyte;
58 if (k1_nullbyte == 0 || k1_nullbyte == 0xff) {
59 if (!sort_field.is_varlen) {
60 kp1 += sort_field.length;
61 kp2 += sort_field.length;
62 }
63 continue; // Both key parts are null, nothing to compare
64 }
65 }
66 if (sort_field.is_varlen) {
67 assert(uint4korr(kp1) >= 4);
68 assert(uint4korr(kp2) >= 4);
69
70 kp1_len = uint4korr(kp1) - 4;
71 kp1 += 4;
72
73 kp2_len = uint4korr(kp2) - 4;
74 kp2 += 4;
75
76 kp_len = std::min(kp1_len, kp2_len);
77 } else {
78 kp_len = kp1_len = kp2_len = sort_field.length;
79 }
80
81 res = memcmp(kp1, kp2, kp_len);
82
83 if (res) return res < 0;
84 if (kp1_len != kp2_len) {
85 if (sort_field.reverse)
86 return kp2_len < kp1_len;
87 else
88 return kp1_len < kp2_len;
89 }
90
91 kp1 += kp1_len;
92 kp2 += kp2_len;
93 }
94
95 if (use_hash) {
96 // Compare hashes at the end of sort keys
97 return memcmp(kp1, kp2, 8) < 0;
98 } else {
99 return false;
100 }
101}
102
103/**
104 This struct is used for merging chunks for filesort()
105 For filesort() with fixed-size keys we use memcmp to compare rows.
106 For variable length keys, we use cmp_varlen_keys to compare rows.
107 */
109 size_t m_len;
111
112 // CTOR for filesort() with fixed-size keys
113 explicit Merge_chunk_greater(size_t len) : m_len(len), m_param(nullptr) {}
114
115 // CTOR for filesort() with varlen keys
116 explicit Merge_chunk_greater(Sort_param *param) : m_len(0), m_param(param) {}
117
118 bool operator()(Merge_chunk *a, Merge_chunk *b) const {
120 }
121
122 bool key_is_greater_than(uchar *key1, uchar *key2) const {
123 // Fixed len keys
124 if (m_len) return memcmp(key1, key2, m_len) > 0;
125
126 if (m_param)
128 key1);
129
130 // We can actually have zero-length sort key for filesort().
131 return false;
132 }
133};
134
135#endif // CMP_VARLEN_KEYS_INCLUDED
Kerberos Client Authentication nullptr
Definition: auth_kerberos_client_plugin.cc:251
A wrapper class which provides array bounds checking.
Definition: sql_array.h:47
There are several record formats for sorting:
Definition: sort_param.h:302
Bounds_checked_array< st_sort_field > local_sortorder
ORDER BY list with some precalculated info for filesort.
Definition: sort_param.h:323
static const uint size_of_varlength_field
Definition: sort_param.h:467
bool use_hash
Definition: sort_param.h:311
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:46
static uint16 key1[1001]
Definition: hp_test2.cc:50
uint32 uint4korr(const char *pT)
Definition: my_byteorder.h:152
unsigned char uchar
Definition: my_inttypes.h:52
This struct is used for merging chunks for filesort() For filesort() with fixed-size keys we use memc...
Definition: cmp_varlen_keys.h:108
Merge_chunk_greater(Sort_param *param)
Definition: cmp_varlen_keys.h:116
bool key_is_greater_than(uchar *key1, uchar *key2) const
Definition: cmp_varlen_keys.h:122
Sort_param * m_param
Definition: cmp_varlen_keys.h:110
bool operator()(Merge_chunk *a, Merge_chunk *b) const
Definition: cmp_varlen_keys.h:118
size_t m_len
Definition: cmp_varlen_keys.h:109
Merge_chunk_greater(size_t len)
Definition: cmp_varlen_keys.h:113
Descriptor for a merge chunk to be sort-merged.
Definition: sql_sort.h:57
uchar * current_key() const
Definition: sql_sort.h:82
Struct that holds information about a sort field.
Definition: sort_param.h:86