Support for optimizer hints NO_SPLIT_MATERIALIZED and
SPLIT_MATERIALIZED. These hints allow fine-grained control
of the "lateral derived" optimization within a query.
Introduces new overload of hint_table_state function which
tells both a hint's value as well as whether it is present.
This is useful to disambiguate cases that the other version
of hint_table_state cannot, such as when a hint is forcing
a behavior in the optimizer that it would not normally do
and the corresponding optimizer switch is enabled.
Implements and tests the optimizer hints DERIVED_CONDITION_PUSHDOWN
and NO_DERIVED_CONDITION_PUSHDOWN, table-level hints to enable and
disable, respectively, the condition pushdown for derived tables
which is typically controlled by the condition_pushdown_for_derived
optimizer switch.
Implements and tests the optimizer hints MERGE and NO_MERGE, table-level
hints to enable and disable, respectively, the derived_merge optimization
which is typically controlled by the derived_merge optimizer switch.
Sometimes hints need to be fixed before TABLE instances are available, but
after TABLE_LIST instances have been created (as in the cases of MERGE and
NO_MERGE). This commit introduces a new function called
fix_hints_for_derived_table to allow early hint fixing for derived tables,
using only a TABLE_LIST instance (so long as such hints are not index-level).
This commit implements optimizer hints allowing to affect the order
of joining tables:
- JOIN_FIXED_ORDER similar to existing STRAIGHT_JOIN hint;
- JOIN_ORDER to apply the specified table order;
- JOIN_PREFIX to hint what tables should be first in the join;
- JOIN_SUFFIX to hint what tables should be last in the join.
- 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);
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.
- Using Lex_ident_sys to scan identifiers, like the SQL parser does.
This fixes handling of double-quote-delimited and backtick-delimited identifiers,
as well as handling of non-ASCII identifiers.
Unescaping and converting from the client character set to the system
character set is now done using Lex_ident_cli_st and Lex_ident_sys,
like it's done in the SQL tokenizer/parser.
Adding helper methods to_ident_cli() and to_ident_sys()
in Optimizer_hint_parser::Token.
- Fixing the hint parser to report a syntax error when an empty identifiers:
SELECT /*+ BKA(``) */ * FROM t1;
- Moving a part of the code from opt_hints_parser.h to opt_hints_parser.cc
Moving these method definitions:
- Optimizer_hint_tokenizer::find_keyword()
- Optimizer_hint_tokenizer::get_token()
to avoid huge pieces of the code in the header file.
- A Lex_ident_cli_st cleanup
Fixing a few Lex_ident_cli_st methods to return Lex_ident_cli_st &
instead of void, to use them easier in the caller code.
- Fixing the hint parser to display the correct line number
Adding a new data type Lex_comment_st
(a combination of LEX_CSTRING and a line number)
Using it in sql_yacc.yy
- Getting rid of redundant dependencies on sql_hints_parser.h
Moving void LEX::resolve_optimizer_hints() from sql_lex.h to sql_lex.cc
Adding a class Optimizer_hint_parser_output, deriving from
Optimizer_hint_parser::Hint_list. Fixing the hint parser to
return a pointer to an allocated instance of Optimizer_hint_parser_output
rather than an instance of Optimizer_hint_parser::Hint_list.
This allows to use a forward declaration of Optimizer_hint_parser_output
in sql_lex.h and thus avoid dependencies on sql_hints_parser.h.
This commit introduces:
- the infrastructure for optimizer hints;
- hints for join buffering: BNL(), NO_BNL(), BKA(), NO_BKA();
- NO_ICP() hint for disabling index condition pushdown;
- MRR(), MO_MRR() hint for multi-range reads control;
- NO_RANGE_OPTIMIZATION() for disabling range optimization;
- QB_NAME() for assigning names for query blocks.
