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MDEV-31496: Make optimizer handle UCASE(varchar_col)=...
(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".- Loading branch information
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,44 @@ | ||
| # Check sargable_casefold rewrite for $collation | ||
|
|
||
| eval create table t1 ( | ||
| col1 varchar(32), | ||
| col2 varchar(32), | ||
| col3 char(32), | ||
| col4 text, | ||
| key(col1), | ||
| key(col2), | ||
| key(col3), | ||
| key(col4(32)) | ||
| ) collate $collation; | ||
|
|
||
| insert into t1 | ||
| select | ||
| concat('A-', seq), | ||
| concat('A-', seq), | ||
| concat('A-', seq), | ||
| concat('A-', seq) | ||
| from seq_1_to_100; | ||
|
|
||
| analyze table t1 persistent for all; | ||
|
|
||
| --echo # Basic examples. All should use ref(col1): | ||
| explain | ||
| select * from t1 where upper(col1)='A-3'; | ||
| select * from t1 where upper(col1)='A-3'; | ||
|
|
||
| explain | ||
| select * from t1 where ucase(col1)='a-3'; | ||
| select * from t1 where ucase(col1)='a-3'; | ||
|
|
||
| explain select * from t1 where 'abc'=upper(col1); | ||
| explain select * from t1 where 'xyz'=ucase(col1); | ||
|
|
||
| create view v1 as select * from t1; | ||
| explain select * from v1 where 'abc'=upper(col1); | ||
| drop view v1; | ||
|
|
||
| explain select * from t1 where upper(col3)='a-3'; | ||
| explain select * from t1 where upper(col4)='a-3'; | ||
|
|
||
| # DROP TABLE t1 is missing intentionally here. | ||
|
|
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,278 @@ | ||
| set | ||
| @tmp_switch_sarg_casefold=@@optimizer_switch, | ||
| optimizer_switch='sargable_casefold=on'; | ||
| create table t1 ( | ||
| col1 varchar(32), | ||
| col2 varchar(32), | ||
| col3 char(32), | ||
| col4 text, | ||
| key(col1), | ||
| key(col2), | ||
| key(col3), | ||
| key(col4(32)) | ||
| ) collate utf8mb3_general_ci; | ||
| insert into t1 | ||
| select | ||
| concat('A-', seq), | ||
| concat('A-', seq), | ||
| concat('A-', seq), | ||
| concat('A-', seq) | ||
| from seq_1_to_100; | ||
| analyze table t1 persistent for all; | ||
| Table Op Msg_type Msg_text | ||
| test.t1 analyze status Engine-independent statistics collected | ||
| test.t1 analyze Warning Engine-independent statistics are not collected for column 'col4' | ||
| test.t1 analyze status Table is already up to date | ||
| # Basic examples. All should use ref(col1): | ||
| explain | ||
| select * from t1 where upper(col1)='A-3'; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 ref col1 col1 99 const 1 Using index condition | ||
| select * from t1 where upper(col1)='A-3'; | ||
| col1 col2 col3 col4 | ||
| A-3 A-3 A-3 A-3 | ||
| explain | ||
| select * from t1 where ucase(col1)='a-3'; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 ref col1 col1 99 const 1 Using index condition | ||
| select * from t1 where ucase(col1)='a-3'; | ||
| col1 col2 col3 col4 | ||
| A-3 A-3 A-3 A-3 | ||
| explain select * from t1 where 'abc'=upper(col1); | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 ref col1 col1 99 const 1 Using index condition | ||
| explain select * from t1 where 'xyz'=ucase(col1); | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 ref col1 col1 99 const 1 Using index condition | ||
| create view v1 as select * from t1; | ||
| explain select * from v1 where 'abc'=upper(col1); | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 ref col1 col1 99 const 1 Using index condition | ||
| drop view v1; | ||
| explain select * from t1 where upper(col3)='a-3'; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 ref col3 col3 97 const 1 Using index condition | ||
| explain select * from t1 where upper(col4)='a-3'; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 ref col4 col4 99 const 1 Using where | ||
| # must not be rewritten: | ||
| explain select * from t1 where ucase(col1 collate utf8mb3_bin)='a-3'; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 ALL NULL NULL NULL NULL 100 Using where | ||
| # Will not do the rewrite due to collation mismatch: | ||
| explain select * from t1 where ucase(col1)=_utf8mb3'abc' COLLATE utf8mb3_bin; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 ALL NULL NULL NULL NULL 100 Using where | ||
| drop table t1; | ||
| create table t1 ( | ||
| col1 varchar(32), | ||
| col2 varchar(32), | ||
| col3 char(32), | ||
| col4 text, | ||
| key(col1), | ||
| key(col2), | ||
| key(col3), | ||
| key(col4(32)) | ||
| ) collate utf8mb4_general_ci; | ||
| insert into t1 | ||
| select | ||
| concat('A-', seq), | ||
| concat('A-', seq), | ||
| concat('A-', seq), | ||
| concat('A-', seq) | ||
| from seq_1_to_100; | ||
| analyze table t1 persistent for all; | ||
| Table Op Msg_type Msg_text | ||
| test.t1 analyze status Engine-independent statistics collected | ||
| test.t1 analyze Warning Engine-independent statistics are not collected for column 'col4' | ||
| test.t1 analyze status Table is already up to date | ||
| # Basic examples. All should use ref(col1): | ||
| explain | ||
| select * from t1 where upper(col1)='A-3'; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 ref col1 col1 131 const 1 Using index condition | ||
| select * from t1 where upper(col1)='A-3'; | ||
| col1 col2 col3 col4 | ||
| A-3 A-3 A-3 A-3 | ||
| explain | ||
| select * from t1 where ucase(col1)='a-3'; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 ref col1 col1 131 const 1 Using index condition | ||
| select * from t1 where ucase(col1)='a-3'; | ||
| col1 col2 col3 col4 | ||
| A-3 A-3 A-3 A-3 | ||
| explain select * from t1 where 'abc'=upper(col1); | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 ref col1 col1 131 const 1 Using index condition | ||
| explain select * from t1 where 'xyz'=ucase(col1); | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 ref col1 col1 131 const 1 Using index condition | ||
| create view v1 as select * from t1; | ||
| explain select * from v1 where 'abc'=upper(col1); | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 ref col1 col1 131 const 1 Using index condition | ||
| drop view v1; | ||
| explain select * from t1 where upper(col3)='a-3'; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 ref col3 col3 129 const 1 Using index condition | ||
| explain select * from t1 where upper(col4)='a-3'; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 ref col4 col4 131 const 1 Using where | ||
| # must not be rewritten: | ||
| explain select * from t1 where ucase(col1 collate utf8mb4_bin)='a-3'; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 ALL NULL NULL NULL NULL 100 Using where | ||
| # Will not do the rewrite due to collation mismatch: | ||
| explain select * from t1 where ucase(col1)=_utf8mb4'abc' COLLATE utf8mb4_bin; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 ALL NULL NULL NULL NULL 100 Using where | ||
| # | ||
| # Check if optimizer_switch turns the rewrite off: | ||
| # | ||
| set | ||
| @save_os=@@optimizer_switch, | ||
| optimizer_switch='sargable_casefold=off'; | ||
| explain select * from t1 where upper(col1)='A-3'; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 ALL NULL NULL NULL NULL 100 Using where | ||
| explain select * from t1 where ucase(col1)='a-3'; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 ALL NULL NULL NULL NULL 100 Using where | ||
| set optimizer_switch=@save_os; | ||
| # The following will not do the rewrite because the comparison | ||
| # is done as DOUBLEs. Come to think of it, it won't harm to do | ||
| # the rewrite but it is outside of the scope of this patch: | ||
| explain select * from t1 where ucase(col1)=123.456; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 ALL NULL NULL NULL NULL 100 Using where | ||
| select | ||
| coercibility(upper(col1)) | ||
| from t1 limit 1; | ||
| coercibility(upper(col1)) | ||
| 2 | ||
| select coercibility(_utf8mb3'abc' COLLATE utf8mb3_bin); | ||
| coercibility(_utf8mb3'abc' COLLATE utf8mb3_bin) | ||
| 0 | ||
| # This is transformed too even if it doesn't create any new | ||
| # [potential] access paths: | ||
| explain format=json select * from t1 where upper(col1)=upper(col2); | ||
| EXPLAIN | ||
| { | ||
| "query_block": { | ||
| "select_id": 1, | ||
| "cost": 0.0256761, | ||
| "nested_loop": [ | ||
| { | ||
| "table": { | ||
| "table_name": "t1", | ||
| "access_type": "ALL", | ||
| "loops": 1, | ||
| "rows": 100, | ||
| "cost": 0.0256761, | ||
| "filtered": 100, | ||
| "attached_condition": "t1.col2 = t1.col1" | ||
| } | ||
| } | ||
| ] | ||
| } | ||
| } | ||
| # | ||
| # Check if ref access works | ||
| # | ||
| create table t2 ( | ||
| a varchar(32), | ||
| non_key varchar(32), | ||
| key(a) | ||
| ) collate utf8mb4_general_ci; | ||
| insert into t2 | ||
| select | ||
| concat('A-', seq), | ||
| concat('A-', seq) | ||
| from seq_1_to_10; | ||
| # Must use ref access for t1: | ||
| explain select * from t1, t2 where upper(t1.col1)= t2.non_key; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t2 ALL NULL NULL NULL NULL 10 Using where | ||
| 1 SIMPLE t1 ref col1 col1 131 test.t2.non_key 1 | ||
| create table t3 ( | ||
| a varchar(32), | ||
| b varchar(32), | ||
| key(a), | ||
| key(b) | ||
| ) collate utf8mb3_general_ci; | ||
| insert into t3 values ('abc','ABC'), ('xyz','XYZ'); | ||
| explain extended | ||
| select a from t3 ignore index(a) where a=b and upper(b)='ABC'; | ||
| id select_type table type possible_keys key key_len ref rows filtered Extra | ||
| 1 SIMPLE t3 ref b b 99 const 1 100.00 Using index condition; Using where | ||
| Warnings: | ||
| Note 1003 select `test`.`t3`.`a` AS `a` from `test`.`t3` IGNORE INDEX (`a`) where `test`.`t3`.`a` = `test`.`t3`.`b` and `test`.`t3`.`b` = 'ABC' | ||
| # | ||
| # Check that rewrite isn't applied for non-applicable collations | ||
| # | ||
| create table t4 ( | ||
| col1 varchar(32) collate utf8mb3_bin, | ||
| col2 varchar(32) collate utf8mb3_czech_ci, | ||
| col3 varchar(32) collate latin1_bin, | ||
| key(col1), | ||
| key(col2), | ||
| key(col3) | ||
| ); | ||
| insert into t4 | ||
| select | ||
| concat('A-', seq), | ||
| concat('A-', seq), | ||
| concat('A-', seq) | ||
| from seq_1_to_100; | ||
| analyze table t4 persistent for all; | ||
| Table Op Msg_type Msg_text | ||
| test.t4 analyze status Engine-independent statistics collected | ||
| test.t4 analyze status Table is already up to date | ||
| # None should use ref access: | ||
| explain select * from t4 where upper(col1)='A-3'; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t4 ALL NULL NULL NULL NULL 100 Using where | ||
| explain select * from t4 where upper(col2)='a-3'; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t4 ALL NULL NULL NULL NULL 100 Using where | ||
| explain select * from t4 where upper(col3)='a-3'; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t4 ALL NULL NULL NULL NULL 100 Using where | ||
| # | ||
| # Check that rewrite works for UPPER(col) IN (const-list) | ||
| # | ||
| set | ||
| @tmp_ot= @@optimizer_trace, | ||
| optimizer_trace=1; | ||
| # must use range: | ||
| explain | ||
| select * from t1 where upper(col1) IN ('A-3','A-4','a-5'); | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 range col1 col1 131 NULL 3 Using index condition | ||
| select * from t1 where upper(col1) IN ('A-3','A-4','a-5'); | ||
| col1 col2 col3 col4 | ||
| A-3 A-3 A-3 A-3 | ||
| A-4 A-4 A-4 A-4 | ||
| A-5 A-5 A-5 A-5 | ||
| # Will not use the rewrite: | ||
| explain | ||
| select * from t1 where upper(col1) IN ('A-3','A-4',col2); | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 ALL NULL NULL NULL NULL 100 Using where | ||
| # | ||
| # MDEV-31946: Optimizer handle UCASE(varchar_col)=... does not work for UPDATE/DELETE | ||
| # | ||
| explain delete from t1 where upper(col1)='A'; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 range col1 col1 131 NULL 1 Using where | ||
| explain delete from t1 where upper(col1) IN ('A','B'); | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 range col1 col1 131 NULL 2 Using where | ||
| explain update t1 set col2='ABC' where upper(col1)='A'; | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 range col1 col1 131 NULL 1 Using where | ||
| explain update t1 set col2='ABC' where upper(col1) IN ('A','B'); | ||
| id select_type table type possible_keys key key_len ref rows Extra | ||
| 1 SIMPLE t1 range col1 col1 131 NULL 2 Using where | ||
| drop table t1,t2,t3,t4; | ||
| set optimizer_switch=@tmp_switch_sarg_casefold; |
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