From 86ae2f3b067ccd5383d06195d3be22a01d42d51c Mon Sep 17 00:00:00 2001 From: "timour/timka@lamia.home" <> Date: Wed, 26 Jul 2006 01:11:19 +0300 Subject: [PATCH] Fix for BUG#20954: avg(keyval) retuns 0.38 but max(keyval) returns an empty set The problem was in that opt_sum_query() replaced MIN/MAX functions with the corresponding constant found in a key, but due to imprecise representation of float numbers, when evaluating the where clause, this comparison failed. When MIN/MAX optimization detects that all tables can be removed, also remove all conjuncts in a where clause that refer to these tables. As a result of this fix, these conditions are not evaluated twice, and in the case of float number comparisons we do not discard result rows due to imprecise float representation. As a side-effect this fix also corrects an unnoticed problem in bug 12882. --- mysql-test/r/func_group.result | 2 ++ mysql-test/r/select.result | 49 ++++++++++++++++++++++++++++++++++ mysql-test/r/subselect.result | 2 +- mysql-test/t/select.test | 30 +++++++++++++++++++++ sql/sql_select.cc | 18 +++++++++++++ 5 files changed, 100 insertions(+), 1 deletion(-) diff --git a/mysql-test/r/func_group.result b/mysql-test/r/func_group.result index ffa68f279f3..932ef133087 100644 --- a/mysql-test/r/func_group.result +++ b/mysql-test/r/func_group.result @@ -824,6 +824,7 @@ select 1, min(a) from t1m where 1=99; 1 NULL select 1, min(1) from t1m where a=99; 1 min(1) +1 NULL select 1, min(1) from t1m where 1=99; 1 min(1) 1 NULL @@ -835,6 +836,7 @@ select 1, max(a) from t1m where 1=99; 1 NULL select 1, max(1) from t1m where a=99; 1 max(1) +1 NULL select 1, max(1) from t1m where 1=99; 1 max(1) 1 NULL diff --git a/mysql-test/r/select.result b/mysql-test/r/select.result index c7df11ab018..d7c01fa5a57 100644 --- a/mysql-test/r/select.result +++ b/mysql-test/r/select.result @@ -2744,3 +2744,52 @@ SELECT i='1e+01',i=1e+01, i in (1e+01), i in ('1e+01') FROM t1; i='1e+01' i=1e+01 i in (1e+01) i in ('1e+01') 0 1 1 1 DROP TABLE t1; +CREATE TABLE t1 (key1 float default NULL, UNIQUE KEY key1 (key1)); +CREATE TABLE t2 (key2 float default NULL, UNIQUE KEY key2 (key2)); +INSERT INTO t1 VALUES (0.3762),(0.3845),(0.6158),(0.7941); +INSERT INTO t2 VALUES (1.3762),(1.3845),(1.6158),(1.7941); +explain select max(key1) from t1 where key1 <= 0.6158; +id select_type table type possible_keys key key_len ref rows Extra +1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Select tables optimized away +explain select max(key2) from t2 where key2 <= 1.6158; +id select_type table type possible_keys key key_len ref rows Extra +1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Select tables optimized away +explain select min(key1) from t1 where key1 >= 0.3762; +id select_type table type possible_keys key key_len ref rows Extra +1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Select tables optimized away +explain select min(key2) from t2 where key2 >= 1.3762; +id select_type table type possible_keys key key_len ref rows Extra +1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Select tables optimized away +explain select max(key1), min(key2) from t1, t2 +where key1 <= 0.6158 and key2 >= 1.3762; +id select_type table type possible_keys key key_len ref rows Extra +1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Select tables optimized away +explain select max(key1) from t1 where key1 <= 0.6158 and rand() + 0.5 >= 0.5; +id select_type table type possible_keys key key_len ref rows Extra +1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Select tables optimized away +explain select min(key1) from t1 where key1 >= 0.3762 and rand() + 0.5 >= 0.5; +id select_type table type possible_keys key key_len ref rows Extra +1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Select tables optimized away +select max(key1) from t1 where key1 <= 0.6158; +max(key1) +0.61580002307892 +select max(key2) from t2 where key2 <= 1.6158; +max(key2) +1.6158000230789 +select min(key1) from t1 where key1 >= 0.3762; +min(key1) +0.37619999051094 +select min(key2) from t2 where key2 >= 1.3762; +min(key2) +1.3761999607086 +select max(key1), min(key2) from t1, t2 +where key1 <= 0.6158 and key2 >= 1.3762; +max(key1) min(key2) +0.61580002307892 1.3761999607086 +select max(key1) from t1 where key1 <= 0.6158 and rand() + 0.5 >= 0.5; +max(key1) +0.61580002307892 +select min(key1) from t1 where key1 >= 0.3762 and rand() + 0.5 >= 0.5; +min(key1) +0.37619999051094 +DROP TABLE t1,t2; diff --git a/mysql-test/r/subselect.result b/mysql-test/r/subselect.result index 595d80f1218..dc921f747ee 100644 --- a/mysql-test/r/subselect.result +++ b/mysql-test/r/subselect.result @@ -539,7 +539,7 @@ EXPLAIN EXTENDED SELECT MAX(numreponse) FROM t1 WHERE numeropost='1'; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Select tables optimized away Warnings: -Note 1003 select max(test.t1.numreponse) AS `MAX(numreponse)` from test.t1 where (test.t1.numeropost = _latin1'1') +Note 1003 select max(test.t1.numreponse) AS `MAX(numreponse)` from test.t1 EXPLAIN EXTENDED SELECT numreponse FROM t1 WHERE numeropost='1' AND numreponse=(SELECT MAX(numreponse) FROM t1 WHERE numeropost='1'); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 const PRIMARY,numreponse PRIMARY 7 const,const 1 Using index diff --git a/mysql-test/t/select.test b/mysql-test/t/select.test index 4cdfc220350..acf9fd77c1b 100644 --- a/mysql-test/t/select.test +++ b/mysql-test/t/select.test @@ -2297,4 +2297,34 @@ INSERT INTO t1 VALUES (10); SELECT i='1e+01',i=1e+01, i in (1e+01), i in ('1e+01') FROM t1; DROP TABLE t1; +# +# Bug #20954 "avg(keyval) retuns 0.38 but max(keyval) returns an empty set" +# +--disable_ps_protocol +CREATE TABLE t1 (key1 float default NULL, UNIQUE KEY key1 (key1)); +CREATE TABLE t2 (key2 float default NULL, UNIQUE KEY key2 (key2)); +INSERT INTO t1 VALUES (0.3762),(0.3845),(0.6158),(0.7941); +INSERT INTO t2 VALUES (1.3762),(1.3845),(1.6158),(1.7941); + +explain select max(key1) from t1 where key1 <= 0.6158; +explain select max(key2) from t2 where key2 <= 1.6158; +explain select min(key1) from t1 where key1 >= 0.3762; +explain select min(key2) from t2 where key2 >= 1.3762; +explain select max(key1), min(key2) from t1, t2 +where key1 <= 0.6158 and key2 >= 1.3762; +explain select max(key1) from t1 where key1 <= 0.6158 and rand() + 0.5 >= 0.5; +explain select min(key1) from t1 where key1 >= 0.3762 and rand() + 0.5 >= 0.5; + +select max(key1) from t1 where key1 <= 0.6158; +select max(key2) from t2 where key2 <= 1.6158; +select min(key1) from t1 where key1 >= 0.3762; +select min(key2) from t2 where key2 >= 1.3762; +select max(key1), min(key2) from t1, t2 +where key1 <= 0.6158 and key2 >= 1.3762; +select max(key1) from t1 where key1 <= 0.6158 and rand() + 0.5 >= 0.5; +select min(key1) from t1 where key1 >= 0.3762 and rand() + 0.5 >= 0.5; + +DROP TABLE t1,t2; +--enable_ps_protocol + # End of 4.1 tests diff --git a/sql/sql_select.cc b/sql/sql_select.cc index fd8a5149edd..96ac98cfb88 100644 --- a/sql/sql_select.cc +++ b/sql/sql_select.cc @@ -547,6 +547,24 @@ JOIN::optimize() } zero_result_cause= "Select tables optimized away"; tables_list= 0; // All tables resolved + /* + Extract all table-independent conditions and replace the WHERE + clause with them. All other conditions were computed by opt_sum_query + and the MIN/MAX/COUNT function(s) have been replaced by constants, + so there is no need to compute the whole WHERE clause again. + Notice that make_cond_for_table() will always succeed to remove all + computed conditions, because opt_sum_query() is applicable only to + conjunctions. + */ + if (conds) + { + COND *table_independent_conds= + make_cond_for_table(conds, PSEUDO_TABLE_BITS, 0); + DBUG_EXECUTE("where", + print_where(table_independent_conds, + "where after opt_sum_query()");); + conds= table_independent_conds; + } } } if (!tables_list)