MySQL 8.4.3
Source Code Documentation
filesort.h
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23
24#ifndef FILESORT_INCLUDED
25#define FILESORT_INCLUDED
26
27#include <stddef.h>
28#include <sys/types.h>
29
30#include "mem_root_array.h"
31#include "my_base.h" /* ha_rows */
32#include "my_dbug.h"
33#include "my_inttypes.h"
34#include "my_table_map.h"
35#include "sql/sort_param.h"
36
37class Addon_fields;
38class Field;
39class JOIN;
40class RowIterator;
41class Sort_result;
42class THD;
43struct ORDER;
44struct TABLE;
45struct st_sort_field;
46
47enum class Addon_fields_status;
48
49/**
50 Sorting related info.
51*/
52class Filesort {
53 public:
55 /// The tables we are sorting.
57 /// If true, do not free the filesort buffers (use if you expect to sort many
58 /// times, like in an uncacheable subquery).
59 const bool keep_buffers;
60 /// Maximum number of rows to return
62 /// ORDER BY list with some precalculated info for filesort
64 /// true means we are using Priority Queue for order by with limit.
67 // If true, we will always sort references to rows on table (and crucially,
68 // the result iterators used will always position the underlying table on
69 // the original row before returning from Read()).
71 // TODO: Consider moving this into private members of Filesort.
73
74 // TODO(sgunders): Change tables to a table_map; however, currently
75 // some semijoin tables are missing from query_block->leaf_tables,
76 // so we can't do that yet.
78 ORDER *order, ha_rows limit_arg, bool remove_duplicates,
79 bool force_sort_rowids, bool unwrap_rollup);
80
82 uint *plength, uint *ppackable_length);
83
84 // Number of elements in the sortorder array.
85 uint sort_order_length() const { return m_sort_order_length; }
86
87 /// Whether we are using addon fields (sort entire rows) or not (sort row
88 /// IDs). Note that on the first call, this actually makes Sort_param
89 /// compute the decision and cache it, so it cannot be called before the sort
90 /// order is properly set up.
91 bool using_addon_fields();
92
93 /// Reset the decision made in using_addon_fields(). Only used in exceptional
94 /// circumstances (see NewWeedoutAccessPathForTables()).
95 void clear_addon_fields();
96
97 private:
98 /* Prepare ORDER BY list for sorting. */
99 uint make_sortorder(ORDER *order, bool unwrap_rollup);
100
102};
103
104bool filesort(THD *thd, Filesort *filesort, RowIterator *source_iterator,
105 table_map tables_to_get_rowid_for, ha_rows num_rows_estimate,
106 Filesort_info *fs_info, Sort_result *sort_result,
108void filesort_free_buffers(TABLE *table, bool full);
109void change_double_for_sort(double nr, uchar *to);
110
111/// Declared here so we can unit test it.
112uint sortlength(THD *thd, st_sort_field *sortorder, uint s_length);
113
114// Avoid pulling in sql/field.h.
115template <bool Is_big_endian>
116void copy_integer(uchar *to, size_t to_length, const uchar *from,
117 size_t from_length, bool is_unsigned);
118
119// Returns whether a sort involving this table would necessarily be on row ID,
120// even if not forced by other means.
121bool SortWillBeOnRowId(const TABLE *table);
122
123static inline void copy_native_longlong(uchar *to, size_t to_length,
124 longlong val, bool is_unsigned) {
125#ifdef WORDS_BIGENDIAN
126 constexpr bool Is_big_endian = true;
127#else
128 constexpr bool Is_big_endian = false;
129#endif
130 copy_integer<Is_big_endian>(to, to_length,
131 static_cast<uchar *>(static_cast<void *>(&val)),
132 sizeof(longlong), is_unsigned);
133}
134
135#endif /* FILESORT_INCLUDED */
This class wraps information about usage of addon fields.
Definition: sort_param.h:129
Definition: field.h:575
A class wrapping misc buffers used for sorting.
Definition: sql_sort.h:189
Sorting related info.
Definition: filesort.h:52
st_sort_field * sortorder
ORDER BY list with some precalculated info for filesort.
Definition: filesort.h:63
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:2260
bool using_pq
true means we are using Priority Queue for order by with limit.
Definition: filesort.h:65
ha_rows limit
Maximum number of rows to return.
Definition: filesort.h:61
bool m_remove_duplicates
Definition: filesort.h:66
Mem_root_array< TABLE * > tables
The tables we are sorting.
Definition: filesort.h:56
uint m_sort_order_length
Definition: filesort.h:101
bool m_force_sort_rowids
Definition: filesort.h:70
THD * m_thd
Definition: filesort.h:54
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:59
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:85
Sort_param m_sort_param
Definition: filesort.h:72
bool using_addon_fields()
Whether we are using addon fields (sort entire rows) or not (sort row IDs).
Definition: filesort.cc:2379
void clear_addon_fields()
Reset the decision made in using_addon_fields().
Definition: filesort.cc:2387
Definition: sql_optimizer.h:133
A typesafe replacement for DYNAMIC_ARRAY.
Definition: mem_root_array.h:426
A context for reading through a single table using a chosen access method: index read,...
Definition: row_iterator.h:82
There are several record formats for sorting:
Definition: sort_param.h:302
Definition: sql_sort.h:156
For each client connection we create a separate thread with THD serving as a thread/connection descri...
Definition: sql_lexer_thd.h:36
void filesort_free_buffers(TABLE *table, bool full)
Definition: filesort.cc:640
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:452
bool SortWillBeOnRowId(const TABLE *table)
Definition: filesort.cc:2189
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:367
static void copy_native_longlong(uchar *to, size_t to_length, longlong val, bool is_unsigned)
Definition: filesort.h:123
void change_double_for_sort(double nr, uchar *to)
Definition: filesort.cc:2394
uint sortlength(THD *thd, st_sort_field *sortorder, uint s_length)
Declared here so we can unit test it.
Definition: filesort.cc:2099
This file includes constants used by all storage engines.
my_off_t ha_rows
Definition: my_base.h:1141
Some integer typedefs for easier portability.
unsigned char uchar
Definition: my_inttypes.h:52
long long int longlong
Definition: my_inttypes.h:55
uint64_t table_map
Definition: my_table_map.h:30
static PFS_engine_table_share_proxy table
Definition: pfs.cc:61
constexpr value_type found_rows
Definition: classic_protocol_constants.h:39
constexpr value_type is_unsigned
Definition: classic_protocol_constants.h:273
R::iterator remove_duplicates(R *rp, LESSF &&lessf=LESSF(), EQUALF &&equalf=EQUALF())
Definition: tablespace_impl.cc:392
Addon_fields_status
Definition: sort_param.h:49
Definition: table.h:286
Definition: table.h:1406
Struct that holds information about a sort field.
Definition: sort_param.h:86