MySQL 8.0.30
Source Code Documentation
filesort.h
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22
23#ifndef FILESORT_INCLUDED
24#define FILESORT_INCLUDED
25
26#include <stddef.h>
27#include <sys/types.h>
28
29#include "mem_root_array.h"
30#include "my_base.h" /* ha_rows */
31#include "my_dbug.h"
32#include "my_inttypes.h"
33#include "my_table_map.h"
34#include "sql/sort_param.h"
35
36class Addon_fields;
37class Field;
38class JOIN;
39class RowIterator;
40class Sort_result;
41class THD;
42struct ORDER;
43struct TABLE;
44struct st_sort_field;
45
46enum class Addon_fields_status;
47
48/**
49 Sorting related info.
50*/
51class Filesort {
52 public:
54 /// The tables we are sorting.
56 /// If true, do not free the filesort buffers (use if you expect to sort many
57 /// times, like in an uncacheable subquery).
58 const bool keep_buffers;
59 /// Maximum number of rows to return
61 /// ORDER BY list with some precalculated info for filesort
63 /// true means we are using Priority Queue for order by with limit.
66 // If true, we will always sort references to rows on table (and crucially,
67 // the result iterators used will always position the underlying table on
68 // the original row before returning from Read()).
70 // TODO: Consider moving this into private members of Filesort.
72
73 // TODO(sgunders): Change tables to a table_map; however, currently
74 // some semijoin tables are missing from query_block->leaf_tables,
75 // so we can't do that yet.
77 ORDER *order, ha_rows limit_arg, bool remove_duplicates,
78 bool force_sort_rowids, bool unwrap_rollup);
79
81 uint *plength, uint *ppackable_length);
82
83 // Number of elements in the sortorder array.
85
86 /// Whether we are using addon fields (sort entire rows) or not (sort row
87 /// IDs). Note that on the first call, this actually makes Sort_param
88 /// compute the decision and cache it, so it cannot be called before the sort
89 /// order is properly set up.
90 bool using_addon_fields();
91
92 /// Reset the decision made in using_addon_fields(). Only used in exceptional
93 /// circumstances (see NewWeedoutAccessPathForTables()).
94 void clear_addon_fields();
95
96 private:
97 /* Prepare ORDER BY list for sorting. */
98 uint make_sortorder(ORDER *order, bool unwrap_rollup);
99
101};
102
103bool filesort(THD *thd, Filesort *filesort, RowIterator *source_iterator,
104 table_map tables_to_get_rowid_for, ha_rows num_rows_estimate,
105 Filesort_info *fs_info, Sort_result *sort_result,
107void filesort_free_buffers(TABLE *table, bool full);
108void change_double_for_sort(double nr, uchar *to);
109
110/// Declared here so we can unit test it.
111uint sortlength(THD *thd, st_sort_field *sortorder, uint s_length);
112
113// Avoid pulling in sql/field.h.
114template <bool Is_big_endian>
115void copy_integer(uchar *to, size_t to_length, const uchar *from,
116 size_t from_length, bool is_unsigned);
117
118// Returns whether a sort involving this table would necessarily be on row ID,
119// even if not forced by other means.
120bool SortWillBeOnRowId(TABLE *table);
121
122static inline void copy_native_longlong(uchar *to, size_t to_length,
123 longlong val, bool is_unsigned) {
124#ifdef WORDS_BIGENDIAN
125 constexpr bool Is_big_endian = true;
126#else
127 constexpr bool Is_big_endian = false;
128#endif
129 copy_integer<Is_big_endian>(to, to_length,
130 static_cast<uchar *>(static_cast<void *>(&val)),
131 sizeof(longlong), is_unsigned);
132}
133
134#endif /* FILESORT_INCLUDED */
This class wraps information about usage of addon fields.
Definition: sort_param.h:128
Definition: field.h:573
A class wrapping misc buffers used for sorting.
Definition: sql_sort.h:188
Sorting related info.
Definition: filesort.h:51
st_sort_field * sortorder
ORDER BY list with some precalculated info for filesort.
Definition: filesort.h:62
uint make_sortorder(ORDER *order, bool unwrap_rollup)
Definition: filesort.cc:674
Addon_fields * get_addon_fields(Addon_fields_status *addon_fields_status, uint *plength, uint *ppackable_length)
Get descriptors of fields appended to sorted fields and calculate their total length.
Definition: filesort.cc:2247
bool using_pq
true means we are using Priority Queue for order by with limit.
Definition: filesort.h:64
ha_rows limit
Maximum number of rows to return.
Definition: filesort.h:60
bool m_remove_duplicates
Definition: filesort.h:65
Mem_root_array< TABLE * > tables
The tables we are sorting.
Definition: filesort.h:55
uint m_sort_order_length
Definition: filesort.h:100
bool m_force_sort_rowids
Definition: filesort.h:69
THD * m_thd
Definition: filesort.h:53
const bool keep_buffers
If true, do not free the filesort buffers (use if you expect to sort many times, like in an uncacheab...
Definition: filesort.h:58
Filesort(THD *thd, Mem_root_array< TABLE * > tables, bool keep_buffers, ORDER *order, ha_rows limit_arg, bool remove_duplicates, bool force_sort_rowids, bool unwrap_rollup)
Definition: filesort.cc:660
uint sort_order_length() const
Definition: filesort.h:84
Sort_param m_sort_param
Definition: filesort.h:71
bool using_addon_fields()
Whether we are using addon fields (sort entire rows) or not (sort row IDs).
Definition: filesort.cc:2364
void clear_addon_fields()
Reset the decision made in using_addon_fields().
Definition: filesort.cc:2372
Definition: sql_optimizer.h:125
A typesafe replacement for DYNAMIC_ARRAY.
Definition: mem_root_array.h:421
A context for reading through a single table using a chosen access method: index read,...
Definition: row_iterator.h:81
There are several record formats for sorting:
Definition: sort_param.h:301
Definition: sql_sort.h:155
For each client connection we create a separate thread with THD serving as a thread/connection descri...
Definition: sql_class.h:922
void filesort_free_buffers(TABLE *table, bool full)
Definition: filesort.cc:640
bool SortWillBeOnRowId(TABLE *table)
Definition: filesort.cc:2177
void copy_integer(uchar *to, size_t to_length, const uchar *from, size_t from_length, bool is_unsigned)
Copies an integer value to a format comparable with memcmp().
Definition: field.h:450
bool filesort(THD *thd, Filesort *filesort, RowIterator *source_iterator, table_map tables_to_get_rowid_for, ha_rows num_rows_estimate, Filesort_info *fs_info, Sort_result *sort_result, ha_rows *found_rows)
Sort a table.
Definition: filesort.cc:366
static void copy_native_longlong(uchar *to, size_t to_length, longlong val, bool is_unsigned)
Definition: filesort.h:122
void change_double_for_sort(double nr, uchar *to)
Definition: filesort.cc:2379
uint sortlength(THD *thd, st_sort_field *sortorder, uint s_length)
Declared here so we can unit test it.
Definition: filesort.cc:2087
This file includes constants used by all storage engines.
my_off_t ha_rows
Definition: my_base.h:1139
Some integer typedefs for easier portability.
unsigned char uchar
Definition: my_inttypes.h:51
long long int longlong
Definition: my_inttypes.h:54
uint64_t table_map
Definition: my_table_map.h:29
constexpr value_type found_rows
Definition: classic_protocol_constants.h:38
constexpr value_type is_unsigned
Definition: classic_protocol_constants.h:268
R::iterator remove_duplicates(R *rp, LESSF &&lessf=LESSF(), EQUALF &&equalf=EQUALF())
Definition: tablespace_impl.cc:391
Addon_fields_status
Definition: sort_param.h:48
Definition: table.h:279
Definition: table.h:1394
Struct that holds information about a sort field.
Definition: sort_param.h:85
unsigned int uint
Definition: uca-dump.cc:29