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MDEV-33281 Optimizer hints code cleanup:

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- remove get_args_printer() from hints printing
 - add append_hint_arguments(THD *thd, opt_hints_enum hint, String *str)
 - add more comments
 - rename st_opt_hint_info::hint_name to hint_type
 - add pptimizer trace support for hints
 - add dbug_print_hints()
 - make print_warn() not be a template
 - introduce Printable_parser_rule interface, make grammar rules that
     emit warnings implement it  and print_warn invokes its function)
 - remove Parser::Hint::append_args() as it is not used anywhere
     (it used to be necessary call print_warn(... (Parser::Hint*)NULL);
This commit is contained in:
Sergei Petrunia
2024-12-08 22:03:01 +02:00
committed by Oleg Smirnov
parent 0e088b5d7e
commit c4fe794d22
10 changed files with 216 additions and 168 deletions
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99
sql/opt_hints.h
View File

@@ -84,6 +84,7 @@
#include "sql_show.h"
#include "mysqld_error.h"
#include "opt_hints_parser.h"
#include "opt_trace.h"
struct LEX;
@@ -111,7 +112,7 @@ enum opt_hints_enum
struct st_opt_hint_info
{
LEX_CSTRING hint_name; // Hint name.
LEX_CSTRING hint_type; // Hint "type", like "BKA" or "MRR".
bool check_upper_lvl; // true if upper level hint check is needed (for hints
// which can be specified on more than one level).
bool has_arguments; // true if hint has additional arguments.
@@ -324,16 +325,16 @@ public:
@param thd Pointer to THD object
*/
void check_unfixed(THD *thd);
/*
Append the name of object(table, index, etc) that hints in this collection
are attached to.
*/
virtual void append_name(THD *thd, String *str)= 0;
/**
Get the function appending additional hint arguments to the printed string,
if the arguments exist. For example, SEMIJOIN and SUBQUERY hints may have
a list of strategies as additional arguments
*/
virtual std::function<void(THD*, String*)> get_args_printer() const
virtual void append_hint_arguments(THD *thd, opt_hints_enum hint, String *str)
{
return [](THD*, String*) {};
DBUG_ASSERT(0);
}
virtual ~Opt_hints() {}
@@ -367,7 +368,7 @@ protected:
/**
Global level hints.
Global level hints. Currently, it's only MAX_EXECUTION_TIME.
*/
class Opt_hints_global : public Opt_hints
@@ -386,14 +387,21 @@ public:
: Opt_hints(Lex_ident_sys(), NULL, mem_root_arg)
{}
virtual void append_name(THD *thd, String *str) override {}
virtual std::function<void(THD*, String*)> get_args_printer() const override
virtual void append_name(THD *thd, String *str) override
{
using std::placeholders::_1;
using std::placeholders::_2;
return std::bind(&Parser::Max_execution_time_hint::append_args,
max_exec_time_hint, _1, _2);
/*
Don't write anything: global hints are not attached to anything named
like a table/query block/etc
*/
}
void append_hint_arguments(THD *thd, opt_hints_enum hint,
String *str) override
{
if (hint == MAX_EXEC_TIME_HINT_ENUM)
max_exec_time_hint->append_args(thd, str);
else
DBUG_ASSERT(0);
}
bool fix_hint(THD *thd);
@@ -403,7 +411,11 @@ public:
class Opt_hints_table;
/**
Query block level hints.
Query block level hints. Currently, these can be:
- QB_NAME (this is interpreted in the parser and is not explicitly
present after that)
- [NO_]SEMIJOIN
- SUBQUERY
*/
class Opt_hints_qb : public Opt_hints
@@ -422,12 +434,7 @@ public:
return name.str ? name : sys_name;
}
/**
Append query block hint.
@param thd pointer to THD object
@param str pointer to String object
*/
void append_qb_hint(THD *thd, String *str)
{
if (name.str)
@@ -437,35 +444,25 @@ public:
str->append(STRING_WITH_LEN(") "));
}
}
/**
Append query block name.
@param thd pointer to THD object
@param str pointer to String object
*/
virtual void append_name(THD *thd, String *str) override
{
/* Append query block name. */
str->append(STRING_WITH_LEN("@"));
const LEX_CSTRING print_name= get_print_name();
append_identifier(thd, str, &print_name);
}
std::function<void(THD*, String*)> get_args_printer() const override
void append_hint_arguments(THD *thd, opt_hints_enum hint,
String *str) override
{
using std::placeholders::_1;
using std::placeholders::_2;
if (semijoin_hint)
{
return std::bind(&Parser::Semijoin_hint::append_args, semijoin_hint,
_1, _2);
}
else if (subquery_hint)
{
return std::bind(&Parser::Subquery_hint::append_args, subquery_hint,
_1, _2);
}
return [](THD*, String*) {};
}
if (hint == SUBQUERY_HINT_ENUM)
subquery_hint->append_args(thd, str);
else if (hint == SEMIJOIN_HINT_ENUM)
semijoin_hint->append_args(thd, str);
else
DBUG_ASSERT(0);
}
/**
Function finds Opt_hints_table object corresponding to
@@ -518,6 +515,19 @@ public:
const Parser::Subquery_hint *subquery_hint= nullptr;
uint subquery_strategy= SUBS_NOT_TRANSFORMED;
void trace_hints(THD *thd)
{
if (unlikely(thd->trace_started()))
{
Json_writer_object obj(thd);
String str;
str.length(0);
print(thd, &str);
// Eventually we may want to print them as array.
obj.add("hints", str.c_ptr_safe());
}
}
};
@@ -635,4 +645,9 @@ bool hint_key_state(const THD *thd, const TABLE *table,
*/
bool hint_table_state(const THD *thd, const TABLE *table,
opt_hints_enum type_arg, bool fallback_value);
#ifndef DBUG_OFF
const char *dbug_print_hints(Opt_hints_qb *hint);
#endif
#endif /* OPT_HINTS_INCLUDED */