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1c2a83179d
(Review input addressed)
After this patch, the optimizer can handle virtual column expressions
in WHERE/ON clauses. If the table has an indexed virtual column:
ALTER TABLE t1
ADD COLUMN vcol INT AS (col1+1),
ADD INDEX idx1(vcol);
and the query uses the exact virtual column expression:
SELECT * FROM t1 WHERE col1+1 <= 100
then the optimizer will be able use index idx1 for it.
This is achieved by walking the WHERE/ON clauses and replacing instances
of virtual column expression (like "col1+1" above) with virtual column's
Item_field (like "vcol"). The latter can be processed by the optimizer.
Replacement is considered (and done) only in items that are potentially
usable to the range optimizer.
29 lines
1 KiB
C
29 lines
1 KiB
C
/*
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Copyright (c) 2009, 2021, MariaDB
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of 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 Street, Fifth Floor, Boston, MA 02110-1335 USA */
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/*
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Interface to indexed virtual column substitution module
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*/
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/* Do substitution in one join */
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bool substitute_indexed_vcols_for_join(JOIN *join);
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/*
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Do substitution for one table and condition. This is for single-table
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UPDATE/DELETE.
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*/
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bool substitute_indexed_vcols_for_table(TABLE *table, Item *item);
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