MySQL 9.0.0
Source Code Documentation
compare_access_paths.h
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23
24#ifndef SQL_JOIN_OPTIMIZER_COMPARE_ACCESS_PATHS_H
25#define SQL_JOIN_OPTIMIZER_COMPARE_ACCESS_PATHS_H
26
27#include <assert.h>
28#include <stdint.h>
29
30#include <cmath>
31
34
35enum class FuzzyComparisonResult : uint32_t {
36 IDENTICAL = 0,
37 FIRST_BETTER = 1,
38 SECOND_BETTER = 2,
41};
42
43// Compare x and y with a given fuzz factor under the assumption that the
44// lesser value is preferred. If the relative difference between x and y
45// is small (x and y are fuzzily identical) we still return information
46// about which one is slightly better.
47inline FuzzyComparisonResult FuzzyComparison(double x, double y,
48 double fuzz_factor) {
49 assert(std::isfinite(x));
50 assert(std::isfinite(y));
51 assert(x >= 0);
52 assert(y >= 0);
53
54 if (fuzz_factor * x < y) {
56 } else if (fuzz_factor * y < x) {
58 } else { // Fuzzily identical
59 if (x < y) {
61 } else if (y < x) {
63 } else {
65 }
66 }
67}
68
74};
75
77 const AccessPath &a,
78 const AccessPath &b,
79 OrderingSet obsolete_orderings);
80
81#endif // SQL_JOIN_OPTIMIZER_COMPARE_ACCESS_PATHS_H
Definition: interesting_orders.h:315
PathComparisonResult
Definition: compare_access_paths.h:69
PathComparisonResult CompareAccessPaths(const LogicalOrderings &orderings, const AccessPath &a, const AccessPath &b, OrderingSet obsolete_orderings)
Definition: join_optimizer.cc:5295
FuzzyComparisonResult FuzzyComparison(double x, double y, double fuzz_factor)
Definition: compare_access_paths.h:47
FuzzyComparisonResult
Definition: compare_access_paths.h:35
Tracks which tuple streams follow which orders, and in particular whether they follow interesting ord...
std::bitset< kMaxSupportedOrderings > OrderingSet
Definition: interesting_orders_defs.h:66
Access paths are a query planning structure that correspond 1:1 to iterators, in that an access path ...
Definition: access_path.h:213