MySQL 9.0.0
Source Code Documentation
print_utils.h
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1/* Copyright (c) 2020, 2024, Oracle and/or its affiliates.
2
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16 but WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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23
24#ifndef SQL_JOIN_OPTIMIZER_PRINT_UTILS
25#define SQL_JOIN_OPTIMIZER_PRINT_UTILS 1
26
27#include "my_compiler.h"
28#include "sql/item.h"
29
30#include <string>
31
33
34/**
35 Like sprintf, but returns an std::string.
36 This is not the most efficient of formatting functions,
37 but it is only intended for debugging/tracing use.
38 */
39std::string StringPrintf(const char *fmt, ...)
40 MY_ATTRIBUTE((format(printf, 1, 2)));
41
42template <class T>
43std::string ItemsToString(const T &items) {
44 std::string result = "(none)";
45 bool first = true;
46 for (Item *item : items) {
47 if (first) {
48 result = ItemToString(item);
49 first = false;
50 } else {
51 result += " AND ";
52 result += ItemToString(item);
53 }
54 }
55 return result;
56}
57
58std::string GenerateExpressionLabel(const RelationalExpression *expr);
59
60/*
61 These functions format a number such that it has reasonable precision
62 without becoming so long that it is hard to read. This is used for
63 EXPLAIN/EXPLAIN ANALYZE, and for describing access paths in optimizer
64 trace.
65
66 * Numbers in the range [0.001, 999999.5> are printed as decimal numbers.
67
68 * All decimal numbers have three significant digits, except for numbers in
69 the range [1000, 999999.5> that have four to six.
70
71 * Numbers outside the range [0.001, 999999.5> are printed on engineering
72 format, i.e. <mantissa>e<sign><exponent> where "mantissa" is a number in
73 the range [1, 999], with three significant digits, and "exponent" is a
74 multiple of three, e.g.: "1.23e+9" and "934e-6".
75
76 * Trailing fractional zeros are not printed. For example, we print "2.3"
77 rather than "2.30", and "1.2e+6" rather than "1.20e+6".
78
79 * Numbers below 1e-12 are printed as "0".
80*/
81std::string FormatNumberReadably(double d);
82std::string FormatNumberReadably(uint64_t l);
83
84#endif // SQL_JOIN_OPTIMIZER_PRINT_UTILS
Base class that is used to represent any kind of expression in a relational query.
Definition: item.h:930
string ItemToString(const Item *item, enum_query_type q_type)
Definition: item.cc:11097
Header for compiler-dependent features.
Definition: gcs_xcom_synode.h:64
struct result result
Definition: result.h:34
std::string ItemsToString(const T &items)
Definition: print_utils.h:43
std::string FormatNumberReadably(double d)
Definition: print_utils.cc:192
std::string StringPrintf(const char *fmt,...)
Like sprintf, but returns an std::string.
Definition: print_utils.cc:42
std::string GenerateExpressionLabel(const RelationalExpression *expr)
Definition: print_utils.cc:64
Represents an expression tree in the relational algebra of joins.
Definition: relational_expression.h:145
Definition: result.h:30