MySQL 9.1.0
Source Code Documentation
reverse_index_range_scan.h
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23
24#ifndef SQL_RANGE_OPTIMIZER_REVERSE_INDEX_RANGE_SCAN_H_
25#define SQL_RANGE_OPTIMIZER_REVERSE_INDEX_RANGE_SCAN_H_
26
27#include <sys/types.h>
28
31#include "sql/sql_list.h"
32
33/**
34 An iterator much like IndexRangeScanIterator, but it scans in the reverse
35 order. This makes it at times more complicated, but since it doesn't support
36 being a part of a ROR scan, it is also less complicated in many ways.
37
38 One could argue that this and IndexRangeScanIterator should be factored into
39 a common base class with separate _ASC and _DESC classes, but they don't
40 actually duplicate that much code.
41 */
43 public:
45 double expected_rows, uint index,
46 MEM_ROOT *return_mem_root, uint mrr_flags,
48 bool using_extended_key_parts);
50 int Read() override;
51 bool Init() override;
52
53 private:
54 static range_seq_t quick_range_rev_seq_init(void *init_param, uint, uint);
55
56 const uint m_index; /* Index this quick select uses */
57 const double m_expected_rows;
59
61 bool inited = false;
62
63 // TODO: pre-allocate space to avoid malloc/free for small number of columns.
65
66 uint m_mrr_flags; /* Flags to be used with MRR interface */
67
68 Bounds_checked_array<QUICK_RANGE *> ranges; /* ordered array of range ptrs */
69 /* Members needed to use the MRR interface */
71
72 QUICK_RANGE *last_range; // The range we are currently scanning, or nullptr.
74
75 /* Info about index we're scanning */
77
78 // Whether this reverse scan uses extended keyparts (in case of Innodb,
79 // secondary index is extended to include primary key).
81
84};
85
86#endif // SQL_RANGE_OPTIMIZER_REVERSE_INDEX_RANGE_SCAN_H_
A wrapper class which provides array bounds checking.
Definition: sql_array.h:47
Definition: key.h:57
Definition: range_optimizer.h:69
An iterator much like IndexRangeScanIterator, but it scans in the reverse order.
Definition: reverse_index_range_scan.h:42
~ReverseIndexRangeScanIterator() override
Definition: reverse_index_range_scan.cc:65
KEY_PART_INFO * key_part_info
Definition: reverse_index_range_scan.h:76
uint m_mrr_flags
Definition: reverse_index_range_scan.h:66
int cmp_prev(QUICK_RANGE *range)
Definition: reverse_index_range_scan.cc:272
bool m_using_extended_key_parts
Definition: reverse_index_range_scan.h:80
static range_seq_t quick_range_rev_seq_init(void *init_param, uint, uint)
Definition: reverse_index_range_scan.cc:282
QUICK_RANGE * last_range
Definition: reverse_index_range_scan.h:72
const double m_expected_rows
Definition: reverse_index_range_scan.h:57
MEM_ROOT * mem_root
Definition: reverse_index_range_scan.h:60
Bounds_checked_array< QUICK_RANGE * > ranges
Definition: reverse_index_range_scan.h:68
int Read() override
Read a single row.
Definition: reverse_index_range_scan.cc:123
const uint m_index
Definition: reverse_index_range_scan.h:56
bool inited
Definition: reverse_index_range_scan.h:61
int current_range_idx
Definition: reverse_index_range_scan.h:73
QUICK_RANGE_SEQ_CTX qr_traversal_ctx
Definition: reverse_index_range_scan.h:70
bool range_reads_after_key(QUICK_RANGE *range)
Definition: reverse_index_range_scan.cc:259
ReverseIndexRangeScanIterator(THD *thd, TABLE *table, ha_rows *examined_rows, double expected_rows, uint index, MEM_ROOT *return_mem_root, uint mrr_flags, Bounds_checked_array< QUICK_RANGE * > ranges, bool using_extended_key_parts)
Definition: reverse_index_range_scan.cc:35
MY_BITMAP column_bitmap
Definition: reverse_index_range_scan.h:64
ha_rows * m_examined_rows
Definition: reverse_index_range_scan.h:58
bool Init() override
Initialize or reinitialize the iterator.
Definition: reverse_index_range_scan.cc:71
THD * thd() const
Definition: row_iterator.h:228
For each client connection we create a separate thread with THD serving as a thread/connection descri...
Definition: sql_lexer_thd.h:36
Definition: row_iterator.h:234
TABLE * table() const
Definition: row_iterator.h:246
my_off_t ha_rows
Definition: my_base.h:1141
void * range_seq_t
Definition: handler.h:3822
The MEM_ROOT is a simple arena, where allocations are carved out of larger blocks.
Definition: my_alloc.h:83
Definition: my_bitmap.h:43
Definition: index_range_scan.h:51
Definition: table.h:1421
Definition: gen_lex_token.cc:149