mirror of
https://github.com/MariaDB/server.git
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e987b9350c
(Review input addressed)
(Added handling of UPDATE/DELETE and partitioning w/o index)
If the properties of the used collation allow, do the following
equivalent rewrites:
1. UPPER(key_col)=expr -> key_col=expr
expr=UPPER(key_col) -> expr=key_col
(also rewrite both sides of the equality at the same time)
2. UPPER(key_col) IN (constant-list) -> key_col IN (constant-list)
- Mark utf8mb{3,4}_general_ci as collations that allow this.
- Add optimizer_switch='sargable_casefold=ON' to control this.
(ON by default in this patch)
- Cover the rewrite in Optimizer Trace, rewrite name is
"sargable_casefold_removal".
61 lines
1.6 KiB
Text
61 lines
1.6 KiB
Text
create table t1 (
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col1 varchar(32),
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col2 varchar(32),
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key(col1),
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key(col2)
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) collate utf8mb3_general_ci;
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insert into t1
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select
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concat('A-', seq),
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concat('A-', seq)
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from seq_1_to_100;
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set
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@tmp_ot= @@optimizer_trace,
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@tmp_os=@@optimizer_switch,
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optimizer_switch='sargable_casefold=on',
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optimizer_trace=1;
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explain select * from t1 where 'abc'=upper(col1);
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ref col1 col1 99 const 1 Using index condition
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select
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json_detailed(json_extract(trace, '$**.sargable_casefold_removal')) as JS
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from information_schema.optimizer_trace;
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JS
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[
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{
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"before": "'abc' = ucase(t1.col1)",
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"after": "'abc' = t1.col1"
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}
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]
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explain select * from t1 where ucase(col2)=upper(col1);
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ALL NULL NULL NULL NULL 100 Using where
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select
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json_detailed(json_extract(trace, '$**.sargable_casefold_removal')) as JS
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from information_schema.optimizer_trace;
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JS
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[
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{
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"before": "ucase(t1.col2) = ucase(t1.col1)",
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"after": "t1.col2 = t1.col1"
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}
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]
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explain
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select * from t1 where upper(col1) IN ('A-3','A-4','a-5');
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 range col1 col1 99 NULL 3 Using index condition
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# Will show the rewrite:
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select
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json_detailed(json_extract(trace, '$**.sargable_casefold_removal')) as JS
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from information_schema.optimizer_trace;
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JS
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[
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{
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"before": "ucase(t1.col1) in ('A-3','A-4','a-5')",
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"after": "t1.col1 in ('A-3','A-4','a-5')"
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}
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]
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set
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optimizer_trace=@tmp_ot,
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optimizer_switch=@tmp_os;
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drop table t1;
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