MySQL 8.0.33
Source Code Documentation
compare_access_paths.h
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22
23#ifndef SQL_JOIN_OPTIMIZER_COMPARE_ACCESS_PATHS_H
24#define SQL_JOIN_OPTIMIZER_COMPARE_ACCESS_PATHS_H
25
26#include <assert.h>
27#include <stdint.h>
28
29#include <cmath>
30
33
34enum class FuzzyComparisonResult : uint32_t {
35 IDENTICAL = 0,
36 FIRST_BETTER = 1,
37 SECOND_BETTER = 2,
40};
41
42// Compare x and y with a given fuzz factor under the assumption that the
43// lesser value is preferred. If the relative difference between x and y
44// is small (x and y are fuzzily identical) we still return information
45// about which one is slightly better.
46inline FuzzyComparisonResult FuzzyComparison(double x, double y,
47 double fuzz_factor) {
48 assert(std::isfinite(x));
49 assert(std::isfinite(y));
50 assert(x >= 0);
51 assert(y >= 0);
52
53 if (fuzz_factor * x < y) {
55 } else if (fuzz_factor * y < x) {
57 } else { // Fuzzily identical
58 if (x < y) {
60 } else if (y < x) {
62 } else {
64 }
65 }
66}
67
73};
74
76 const AccessPath &a,
77 const AccessPath &b,
78 OrderingSet obsolete_orderings);
79
80#endif // SQL_JOIN_OPTIMIZER_COMPARE_ACCESS_PATHS_H
Definition: interesting_orders.h:313
PathComparisonResult
Definition: compare_access_paths.h:68
PathComparisonResult CompareAccessPaths(const LogicalOrderings &orderings, const AccessPath &a, const AccessPath &b, OrderingSet obsolete_orderings)
Definition: join_optimizer.cc:4110
FuzzyComparisonResult FuzzyComparison(double x, double y, double fuzz_factor)
Definition: compare_access_paths.h:46
FuzzyComparisonResult
Definition: compare_access_paths.h:34
Tracks which tuple streams follow which orders, and in particular whether they follow interesting ord...
std::bitset< kMaxSupportedOrderings > OrderingSet
Definition: interesting_orders_defs.h:65
Access paths are a query planning structure that correspond 1:1 to iterators, in that an access path ...
Definition: access_path.h:192