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This patch implements support for implicit query block (QB) names in
optimizer hints, allowing hints to reference query blocks and tables
within derived tables, views and CTEs without requiring explicit
QB_NAME hints.
Examples.
-- Addressing a table inside a derived table using implicit QB name
select /*+ no_index(t1@dt) */ *
from (select * from t1 where a > 10) as DT;
-- this is an equivalent to:
select /*+ no_index(t1@dt) */ * from
(select /*+ qb_name(dt)*/ * from t1 where a > 10) as DT;
-- Addressing a query block corresponding to the derived table
select /*+ no_bnl(@dt) */ *
from (select * from t1, t2 where t.1.a > t2.a) as DT;
-- View
create view v1 as select * from t1 where a > 10 and b > 100;
-- referencing a table inside a view by implicit QB name:
select /*+ index_merge(t1@v1 idx_a, idx_b) */ *
from v1, t2 where v1.a = t2.a;
-- equivalent to:
create view v1 as select /*+ qb_name(qb_v1) */ *
from t1 where a > 10 and b > 100;
select /*+ index_merge(t1@qb_v1 idx_a, idx_b) */ *
from v1, t2 where v1.a = t2.a;
-- CTE
with aless100 as (select a from t1 where b <100)
select /*+ index(t1@aless100) */ * from aless100;
-- equivalent to:
with aless100 as (select /*+ qb_name(aless100) */ a from t1 where b <100)
select /*+ index(t1@aless100) */ * from aless100;
Limitations:
- Only SELECT statements support implicit QB names. DML operations
(UPDATE, DELETE, INSERT) only support explicit QB names
54 lines
1.5 KiB
C
54 lines
1.5 KiB
C
#ifndef OPT_HINTS_STRUCTS_H
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#define OPT_HINTS_STRUCTS_H
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/*
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Copyright (c) 2026, MariaDB
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; version 2 of
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the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 USA
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*/
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/**
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Hint types, MAX_HINT_ENUM should be always last.
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This enum should be synchronized with opt_hint_info
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array(see opt_hints.cc).
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*/
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enum opt_hints_enum
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{
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BKA_HINT_ENUM= 0,
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BNL_HINT_ENUM,
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ICP_HINT_ENUM,
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MRR_HINT_ENUM,
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NO_RANGE_HINT_ENUM,
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QB_NAME_HINT_ENUM,
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MAX_EXEC_TIME_HINT_ENUM,
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SEMIJOIN_HINT_ENUM,
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SUBQUERY_HINT_ENUM,
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JOIN_PREFIX_HINT_ENUM,
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JOIN_SUFFIX_HINT_ENUM,
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JOIN_ORDER_HINT_ENUM,
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JOIN_FIXED_ORDER_HINT_ENUM,
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DERIVED_CONDITION_PUSHDOWN_HINT_ENUM,
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MERGE_HINT_ENUM,
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SPLIT_MATERIALIZED_HINT_ENUM,
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INDEX_HINT_ENUM,
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JOIN_INDEX_HINT_ENUM,
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GROUP_INDEX_HINT_ENUM,
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ORDER_INDEX_HINT_ENUM,
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ROWID_FILTER_HINT_ENUM,
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INDEX_MERGE_HINT_ENUM,
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MAX_HINT_ENUM // This one must be the last in the list
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};
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#endif /* OPT_HINTS_STRUCTS_H */
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