Hello Igor, Could you please review the below? The bug page https://bugs.launchpad.net/maria/+bug/727667 has verbose explanations of how we ended up having this bug, as well as justifications for fixing it in this particular way. ----- Forwarded message from Sergey Petrunya ----- From: Sergey Petrunya To: commits@mariadb.org X-Mailer: mail (GNU Mailutils 1.2) Date: Sat, 5 Mar 2011 12:56:26 +0300 (MSK) Subject: [Commits] Rev 2933: BUG#727667 Wrong result with OR + NOT NULL in maria-5.3 in file:///home/psergey/dev2/5.3/ At file:///home/psergey/dev2/5.3/ ------------------------------------------------------------ revno: 2933 revision-id: psergey@askmonty.org-20110305095622-wzlnwr9srfbsu3pv parent: psergey@askmonty.org-20110304091446-qmsezak3c0cfm9b1 committer: Sergey Petrunya branch nick: 5.3 timestamp: Sat 2011-03-05 12:56:22 +0300 message: BUG#727667 Wrong result with OR + NOT NULL in maria-5.3 - put the code that sets HA_NULL_PART bit back - Fix test_if_ref/part_of_refkey() so that = NULL-ability of lookup columns does not prevent the equality from being removed (we now have early/late NULLs filtering which will filter out NULL values) = equality is not removed if it is ref_or_null access, and the value of the lookup column can alternate between the lookup value and NULL. === modified file 'mysql-test/r/null.result' --- a/mysql-test/r/null.result 2009-12-15 07:16:46 +0000 +++ b/mysql-test/r/null.result 2011-03-05 09:56:22 +0000 @@ -170,7 +170,7 @@ insert into t1 values(null); explain select * from t1 where i=2 or i is null; id select_type table type possible_keys key key_len ref rows Extra -1 SIMPLE t1 ref_or_null i i 5 const 9 Using index +1 SIMPLE t1 ref_or_null i i 5 const 9 Using where; Using index select count(*) from t1 where i=2 or i is null; count(*) 10 === modified file 'mysql-test/r/null_key.result' --- a/mysql-test/r/null_key.result 2010-10-06 20:27:12 +0000 +++ b/mysql-test/r/null_key.result 2011-03-05 09:56:22 +0000 @@ -21,10 +21,10 @@ 1 SIMPLE t1 range a,b a 9 NULL 3 Using where; Using index explain select * from t1 where (a is null or a = 7) and b=7; id select_type table type possible_keys key key_len ref rows Extra -1 SIMPLE t1 ref_or_null a,b a 9 const,const 2 Using index +1 SIMPLE t1 ref_or_null a,b a 9 const,const 2 Using where; Using index explain select * from t1 where (a is null or a = 7) and b=7 order by a; id select_type table type possible_keys key key_len ref rows Extra -1 SIMPLE t1 ref_or_null a,b a 9 const,const 2 Using index; Using filesort +1 SIMPLE t1 ref_or_null a,b a 9 const,const 2 Using where; Using index; Using filesort explain select * from t1 where (a is null and b>a) or a is null and b=7 limit 2; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ref a,b a 5 const 3 Using where; Using index @@ -151,7 +151,7 @@ insert into t1 values (7,null), (8,null), (8,7); explain select * from t1 where a = 7 and (b=7 or b is null); id select_type table type possible_keys key key_len ref rows Extra -1 SIMPLE t1 ref_or_null a,b a 10 const,const 2 Using index +1 SIMPLE t1 ref_or_null a,b a 10 const,const 2 Using where; Using index select * from t1 where a = 7 and (b=7 or b is null); a b 7 7 @@ -166,7 +166,7 @@ NULL 7 explain select * from t1 where (a = 7 or a is null) and (a = 7 or a is null); id select_type table type possible_keys key key_len ref rows Extra -1 SIMPLE t1 ref_or_null a a 5 const 5 Using index +1 SIMPLE t1 ref_or_null a a 5 const 5 Using where; Using index select * from t1 where (a = 7 or a is null) and (a = 7 or a is null); a b 7 NULL @@ -192,7 +192,7 @@ explain select * from t2,t1 where t1.a=t2.a and (b= 7 or b is null); id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 ALL NULL NULL NULL NULL 2 Using where -1 SIMPLE t1 ref_or_null a a 10 test.t2.a,const 4 Using index +1 SIMPLE t1 ref_or_null a a 10 test.t2.a,const 4 Using where; Using index select * from t2,t1 where t1.a=t2.a and (b= 7 or b is null); a a b 7 7 7 @@ -202,7 +202,7 @@ explain select * from t2,t1 where (t1.a=t2.a or t1.a is null) and b= 7; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 ALL NULL NULL NULL NULL 2 -1 SIMPLE t1 ref_or_null a a 10 test.t2.a,const 4 Using index +1 SIMPLE t1 ref_or_null a a 10 test.t2.a,const 4 Using where; Using index select * from t2,t1 where (t1.a=t2.a or t1.a is null) and b= 7; a a b 7 7 7 @@ -226,7 +226,7 @@ explain select * from t2,t1 where t1.a=t2.a or t1.a is null; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 ALL NULL NULL NULL NULL 4 -1 SIMPLE t1 ref_or_null a a 5 test.t2.a 4 Using index +1 SIMPLE t1 ref_or_null a a 5 test.t2.a 4 Using where; Using index explain select * from t2,t1 where t1.a<=>t2.a or (t1.a is null and t1.b <> 9); id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 ALL NULL NULL NULL NULL 4 @@ -447,3 +447,15 @@ 3 12 0 12 drop table t1, t2; End of 5.0 tests +# +# BUG#727667 Wrong result with OR + NOT NULL in maria-5.3 +# +CREATE TABLE t1 ( +f3 int(11), +f10 varchar(1), +KEY (f3) +); +INSERT INTO t1 VALUES ('9','k'),(NULL,'r'); +SELECT * FROM t1 WHERE (f3 = 83) OR (f10 = 'z' AND f3 IS NULL); +f3 f10 +DROP TABLE t1; === modified file 'mysql-test/r/order_by.result' --- a/mysql-test/r/order_by.result 2011-01-27 04:45:23 +0000 +++ b/mysql-test/r/order_by.result 2011-03-05 09:56:22 +0000 @@ -643,7 +643,7 @@ insert into t1 values (2, 1), (1, 1), (4, NULL), (3, NULL), (6, 2), (5, 2); explain select * from t1 where b=1 or b is null order by a; id select_type table type possible_keys key key_len ref rows Extra -1 SIMPLE t1 ref_or_null b b 5 const 3 Using filesort +1 SIMPLE t1 ref_or_null b b 5 const 3 Using index condition; Using filesort select * from t1 where b=1 or b is null order by a; a b 1 1 @@ -652,7 +652,7 @@ 4 NULL explain select * from t1 where b=2 or b is null order by a; id select_type table type possible_keys key key_len ref rows Extra -1 SIMPLE t1 ref_or_null b b 5 const 4 Using filesort +1 SIMPLE t1 ref_or_null b b 5 const 4 Using index condition; Using filesort select * from t1 where b=2 or b is null order by a; a b 3 NULL === modified file 'mysql-test/r/subselect.result' --- a/mysql-test/r/subselect.result 2011-02-22 09:15:47 +0000 +++ b/mysql-test/r/subselect.result 2011-03-05 09:56:22 +0000 @@ -906,7 +906,7 @@ explain extended SELECT t1.a, t1.a in (select t2.a from t2,t3 where t3.a=t2.a) FROM t1; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t1 index NULL PRIMARY 4 NULL 4 100.00 Using index -2 DEPENDENT SUBQUERY t2 ref_or_null a a 5 func 2 100.00 Using index +2 DEPENDENT SUBQUERY t2 ref_or_null a a 5 func 2 100.00 Using where; Using index 2 DEPENDENT SUBQUERY t3 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (flat, BNL join) Warnings: Note 1003 select `test`.`t1`.`a` AS `a`,<`test`.`t1`.`a`>((`test`.`t1`.`a`,<exists>(select 1 from `test`.`t2` join `test`.`t3` where ((`test`.`t3`.`a` = `test`.`t2`.`a`) and ((<cache>(`test`.`t1`.`a`) = `test`.`t2`.`a`) or isnull(`test`.`t2`.`a`))) having (`test`.`t2`.`a`)))) AS `t1.a in (select t2.a from t2,t3 where t3.a=t2.a)` from `test`.`t1` === modified file 'mysql-test/r/subselect_no_mat.result' --- a/mysql-test/r/subselect_no_mat.result 2011-02-22 09:15:47 +0000 +++ b/mysql-test/r/subselect_no_mat.result 2011-03-05 09:56:22 +0000 @@ -910,7 +910,7 @@ explain extended SELECT t1.a, t1.a in (select t2.a from t2,t3 where t3.a=t2.a) FROM t1; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t1 index NULL PRIMARY 4 NULL 4 100.00 Using index -2 DEPENDENT SUBQUERY t2 ref_or_null a a 5 func 2 100.00 Using index +2 DEPENDENT SUBQUERY t2 ref_or_null a a 5 func 2 100.00 Using where; Using index 2 DEPENDENT SUBQUERY t3 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (flat, BNL join) Warnings: Note 1003 select `test`.`t1`.`a` AS `a`,<`test`.`t1`.`a`>((`test`.`t1`.`a`,<exists>(select 1 from `test`.`t2` join `test`.`t3` where ((`test`.`t3`.`a` = `test`.`t2`.`a`) and ((<cache>(`test`.`t1`.`a`) = `test`.`t2`.`a`) or isnull(`test`.`t2`.`a`))) having (`test`.`t2`.`a`)))) AS `t1.a in (select t2.a from t2,t3 where t3.a=t2.a)` from `test`.`t1` === modified file 'mysql-test/r/subselect_no_opts.result' --- a/mysql-test/r/subselect_no_opts.result 2011-02-22 09:15:47 +0000 +++ b/mysql-test/r/subselect_no_opts.result 2011-03-05 09:56:22 +0000 @@ -907,7 +907,7 @@ explain extended SELECT t1.a, t1.a in (select t2.a from t2,t3 where t3.a=t2.a) FROM t1; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t1 index NULL PRIMARY 4 NULL 4 100.00 Using index -2 DEPENDENT SUBQUERY t2 ref_or_null a a 5 func 2 100.00 Using index +2 DEPENDENT SUBQUERY t2 ref_or_null a a 5 func 2 100.00 Using where; Using index 2 DEPENDENT SUBQUERY t3 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (flat, BNL join) Warnings: Note 1003 select `test`.`t1`.`a` AS `a`,<`test`.`t1`.`a`>((`test`.`t1`.`a`,<exists>(select 1 from `test`.`t2` join `test`.`t3` where ((`test`.`t3`.`a` = `test`.`t2`.`a`) and ((<cache>(`test`.`t1`.`a`) = `test`.`t2`.`a`) or isnull(`test`.`t2`.`a`))) having (`test`.`t2`.`a`)))) AS `t1.a in (select t2.a from t2,t3 where t3.a=t2.a)` from `test`.`t1` === modified file 'mysql-test/r/subselect_no_semijoin.result' --- a/mysql-test/r/subselect_no_semijoin.result 2011-02-22 09:15:47 +0000 +++ b/mysql-test/r/subselect_no_semijoin.result 2011-03-05 09:56:22 +0000 @@ -907,7 +907,7 @@ explain extended SELECT t1.a, t1.a in (select t2.a from t2,t3 where t3.a=t2.a) FROM t1; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t1 index NULL PRIMARY 4 NULL 4 100.00 Using index -2 DEPENDENT SUBQUERY t2 ref_or_null a a 5 func 2 100.00 Using index +2 DEPENDENT SUBQUERY t2 ref_or_null a a 5 func 2 100.00 Using where; Using index 2 DEPENDENT SUBQUERY t3 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (flat, BNL join) Warnings: Note 1003 select `test`.`t1`.`a` AS `a`,<`test`.`t1`.`a`>((`test`.`t1`.`a`,<exists>(select 1 from `test`.`t2` join `test`.`t3` where ((`test`.`t3`.`a` = `test`.`t2`.`a`) and ((<cache>(`test`.`t1`.`a`) = `test`.`t2`.`a`) or isnull(`test`.`t2`.`a`))) having (`test`.`t2`.`a`)))) AS `t1.a in (select t2.a from t2,t3 where t3.a=t2.a)` from `test`.`t1` === modified file 'mysql-test/t/null_key.test' --- a/mysql-test/t/null_key.test 2008-03-03 17:35:44 +0000 +++ b/mysql-test/t/null_key.test 2011-03-05 09:56:22 +0000 @@ -263,3 +263,16 @@ drop table t1, t2; -- echo End of 5.0 tests +--echo # +--echo # BUG#727667 Wrong result with OR + NOT NULL in maria-5.3 +--echo # + +CREATE TABLE t1 ( + f3 int(11), + f10 varchar(1), + KEY (f3) +); +INSERT INTO t1 VALUES ('9','k'),(NULL,'r'); +SELECT * FROM t1 WHERE (f3 = 83) OR (f10 = 'z' AND f3 IS NULL); +DROP TABLE t1; + === modified file 'sql/sql_select.cc' --- a/sql/sql_select.cc 2011-02-28 21:29:59 +0000 +++ b/sql/sql_select.cc 2011-03-05 09:56:22 +0000 @@ -6564,10 +6564,12 @@ j->ref.has_record= FALSE; j->ref.null_rejecting= 0; j->ref.disable_cache= FALSE; + j->ref.null_ref_part= (uint)-1; keyuse=org_keyuse; store_key **ref_key= j->ref.key_copy; uchar *key_buff=j->ref.key_buff, *null_ref_key= 0; + uint null_ref_part= (uint)-1; bool keyuse_uses_no_tables= TRUE; if (ftkey) { @@ -6621,7 +6623,10 @@ instead of JT_REF_OR_NULL in case if field can't be null */ if ((keyuse->optimize & KEY_OPTIMIZE_REF_OR_NULL) && maybe_null) + { null_ref_key= key_buff; + null_ref_part= i; + } key_buff+= keyinfo->key_part[i].store_length; } } /* not ftkey */ @@ -6636,6 +6641,7 @@ /* Must read with repeat */ j->type= null_ref_key ? JT_REF_OR_NULL : JT_REF; j->ref.null_ref_key= null_ref_key; + j->ref.null_ref_part= null_ref_part; } else if (keyuse_uses_no_tables) { @@ -15287,8 +15293,12 @@ *****************************************************************************/ /** + Check if "left_item=right_item" equality is guaranteed to be true by use of + [eq]ref access on left_item->field->table. + @return - 1 if right_item is used removable reference key on left_item + TRUE if right_item is used removable reference key on left_item + FALSE otherwise */ bool test_if_ref(Item *root_cond, Item_field *left_item,Item *right_item) @@ -15301,7 +15311,11 @@ (!join_tab->first_inner || *join_tab->first_inner->on_expr_ref == root_cond)) { - // Cond guards + /* + If ref access uses "Full scan on NULL key" (i.e. it actually alternates + between ref access and full table scan), then no equality can be + guaranteed to be true. + */ for (uint i = 0; i < join_tab->ref.key_parts; i++) { if (join_tab->ref.cond_guards[i]) @@ -15309,7 +15323,7 @@ return FALSE; } } - // + Item *ref_item=part_of_refkey(field->table,field); if (ref_item && ref_item->eq(right_item,1)) { @@ -15611,6 +15625,29 @@ } +/* + @brief + + Check if + - @table uses "ref"-like access + - it is based on "@field=certain_item" equality + - the equality will be true for any record returned by the access method + and return the certain_item if yes. + + @detail + + Equality won't necessarily hold if: + - the used index covers only part of the @field. + Suppose, we have a CHAR(5) field and INDEX(field(3)). if you make a lookup + for 'abc', you will get both record with 'abc' and with 'abcde'. + - The type of access is actually ref_or_null, and so @field can be either + a value or NULL. + + @return + Item that the field will be equal to + NULL if no such item +*/ + static Item * part_of_refkey(TABLE *table,Field *field) { @@ -15619,17 +15656,30 @@ return (Item*) 0; // field from outer non-select (UPDATE,...) uint ref_parts= join_tab->ref.key_parts; - if (ref_parts) + if (ref_parts) /* if it's ref/eq_ref/ref_or_null */ { - uint key= join_tab->ref.key; KEY *key_info= join_tab->get_keyinfo_by_key_no(key); KEY_PART_INFO *key_part= key_info->key_part; for (uint part=0 ; part < ref_parts ; part++,key_part++) - if (field->eq(key_part->field) && - !(key_part->key_part_flag & (HA_PART_KEY_SEG | HA_NULL_PART))) - return join_tab->ref.items[part]; + { + if (field->eq(key_part->field)) + { + /* + Found the field in the key. Check that + 1. ref_or_null doesn't alternate this component between a value and + a NULL + 2. index fully covers the key + */ + if (part != join_tab->ref.null_ref_part && // (1) + !(key_part->key_part_flag & HA_PART_KEY_SEG)) // (2) + { + return join_tab->ref.items[part]; + } + break; + } + } } return (Item*) 0; } === modified file 'sql/sql_select.h' --- a/sql/sql_select.h 2011-02-24 06:23:12 +0000 +++ b/sql/sql_select.h 2011-03-05 09:56:22 +0000 @@ -109,8 +109,15 @@ */ key_part_map null_rejecting; table_map depend_map; ///< Table depends on these tables. + /* null byte position in the key_buf. Used for REF_OR_NULL optimization */ uchar *null_ref_key; + /* + ref_or_null optimization: number of key part can be NULL (there's only one) + uint(-1) if no part can be NULL. + */ + uint null_ref_part; + /* The number of times the record associated with this key was used in the join. === modified file 'sql/table.cc' --- a/sql/table.cc 2011-02-22 09:15:47 +0000 +++ b/sql/table.cc 2011-03-05 09:56:22 +0000 @@ -1581,6 +1581,8 @@ #endif key_part->key_part_flag|= HA_PART_KEY_SEG; } + if (field->real_maybe_null()) + key_part->key_part_flag|= HA_NULL_PART; /* Sometimes we can compare key parts for equality with memcmp. But not always. _______________________________________________ commits mailing list commits@mariadb.org https://lists.askmonty.org/cgi-bin/mailman/listinfo/commits ----- End forwarded message ----- -- BR Sergey -- Sergey Petrunia, Software Developer Monty Program AB, http://askmonty.org Blog: http://s.petrunia.net/blog