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MDEV-34860 Implement MAX_EXECUTION_TIME hint

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It places a limit N (a timeout value in milliseconds) on how long
a statement is permitted to execute before the server terminates it.

Syntax:
SELECT /*+ MAX_EXECUTION_TIME(milliseconds) */ ...

Only top-level SELECT statements support the hint.
This commit is contained in:
Oleg Smirnov
2024-08-07 22:10:50 +07:00
parent 1e2774d829
commit 67319f3e8d
20 changed files with 573 additions and 51 deletions
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59
sql/opt_hints_parser.h
View File

@@ -22,6 +22,7 @@
#include "simple_tokenizer.h"
#include "sql_list.h"
#include "sql_string.h"
#include "sql_type_int.h"
#include "simple_parser.h"
class st_select_lex;
@@ -72,9 +73,11 @@ public:
keyword_NO_RANGE_OPTIMIZATION,
keyword_MRR,
keyword_QB_NAME,
keyword_MAX_EXECUTION_TIME,
// Other token types
tIDENT
tIDENT,
tUNSIGNED_NUMBER
};
class Token: public Lex_cstring
@@ -240,6 +243,13 @@ private:
using TOKEN::TOKEN;
};
class Keyword_MAX_EXECUTION_TIME:
public TOKEN<Parser, TokenID::keyword_MAX_EXECUTION_TIME>
{
public:
using TOKEN::TOKEN;
};
class Identifier: public TOKEN<Parser, TokenID::tIDENT>
{
public:
@@ -258,6 +268,28 @@ private:
}
};
class Unsigned_Number: public TOKEN<Parser, TokenID::tUNSIGNED_NUMBER>
{
public:
using TOKEN::TOKEN;
/*
Converts token string to a non-negative number ( >=0 ).
Returns the converted number if the conversion succeeds.
Returns non-NULL ULonglong_null value on successful string conversion and
NULL ULonglong_null if the conversion failed or the number is negative
*/
ULonglong_null get_ulonglong() const
{
int error;
char *end= const_cast<char *>(str + length);
longlong n= my_strtoll10(str, &end, &error);
if (error != 0 || end != str + length || n < 0)
return ULonglong_null(0, true);
return ULonglong_null(n, false);
}
};
class LParen: public TOKEN<Parser, TokenID::tLPAREN>
{
public:
@@ -554,21 +586,40 @@ private:
};
public:
// max_execution_time_hint ::= MAX_EXECUTION_TIME ( milliseconds )
class Max_execution_time_hint: public AND4<Parser,
Keyword_MAX_EXECUTION_TIME,
LParen,
Unsigned_Number,
RParen>
{
public:
using AND4::AND4;
bool resolve(Parse_context *pc) const;
void append_args(THD *thd, String *str) const;
ulong get_milliseconds() const;
};
/*
hint ::= index_level_hint
| table_level_hint
| qb_name_hint
| statement_level_hint
*/
class Hint: public OR3<Parser,
class Hint: public OR4<Parser,
Index_level_hint,
Table_level_hint,
Qb_name_hint>
Qb_name_hint,
Max_execution_time_hint>
{
public:
using OR3::OR3;
using OR4::OR4;
};
private:
// hint_list ::= hint [ hint... ]
class Hint_list_container: public List<Hint>
{