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3fa99f0c0e
The main difference in code path between EQ_REF and REF is that for REF we have to do an extra read_next on the index to check that there is no more matching rows. Before this patch we added a preference of EQ_REF by ensuring that REF would always estimate to find at least 2 rows. This patch adds the cost of the extra key read_next to REF access and removes the code that limited REF to at least 2 rows. For some queries this can have a big effect as the total estimated rows will be halved for each REF table with 1 rows. multi_range cost calculations are also changed to take into account the difference between EQ_REF and REF. The effect of the patch to the test suite: - About 80 test case changed - Almost all changes where for EXPLAIN where estimated rows for REF where changed from 2 to 1. - A few test cases using explain extended had a change of 'filtered'. This is because of the estimated rows are now closer to the calculated selectivity. - A very few test had a change of table order. This is because the change of estimated rows from 2 to 1 or the small cost change for REF (main.subselect_sj_jcl6, main.group_by, main.dervied_cond_pushdown, main.distinct, main.join_nested, main.order_by, main.join_cache) - No key statistics and the estimated rows are now smaller which cased estimated filtering to be lower. (main.subselect_sj_mat) - The number of total rows are halved. (main.derived_cond_pushdown) - Plans with 1 row changed to use RANGE instead of REF. (main.group_min_max) - ALL changed to REF (main.key_diff) - Key changed from ref + index_only to PRIMARY key for InnoDB, as OPTIMIZER_ROW_LOOKUP_COST + OPTIMIZER_ROW_NEXT_FIND_COST is smaller than OPTIMIZER_KEY_LOOKUP_COST + OPTIMIZER_KEY_NEXT_FIND_COST. (main.join_outer_innodb) - Cost changes printouts (main.opt_trace*) - Result order change (innodb_gis.rtree)
94 lines
3.1 KiB
Text
94 lines
3.1 KiB
Text
flush status;
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show status like "%custom_aggregate%";
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Variable_name Value
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Feature_custom_aggregate_functions 0
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create table t2 (sal int(10));
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create table t3 (sal int(10),id int);
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insert into t3 values (0,1),(1,2),(2,3),(3,4);
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create aggregate function f1(x INT) returns int
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begin
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declare tot_sum int default 0;
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declare continue handler for not found return tot_sum;
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loop
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fetch group next row;
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set tot_sum= tot_sum + x;
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end loop;
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end|
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create aggregate function f2 (x int) returns int
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begin
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declare counter int default 0;
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declare continue handler for not found return 0;
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loop
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fetch group next row;
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set counter =counter + (select f1(sal) from t1);
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end loop;
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end|
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create table t1 (sal int(10),id int(10));
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INSERT INTO t1 (sal,id) VALUES (5000,1);
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INSERT INTO t1 (sal,id) VALUES (2000,2);
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INSERT INTO t1 (sal,id) VALUES (1000,3);
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Normal select with custom aggregate function
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select f1(sal) from t1 where id>= 1;
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f1(sal)
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8000
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show status like "%custom_aggregate%";
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Variable_name Value
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Feature_custom_aggregate_functions 1
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subqueries with custom aggregates
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explain
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select * from t1, (select f1(sal) as a from t1 where id>= 1) q where q.a=t1.sal;
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 3 Using where
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1 PRIMARY <derived2> ref key0 key0 5 test.t1.sal 1
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2 DERIVED t1 ALL NULL NULL NULL NULL 3 Using where
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show status like "%custom_aggregate%";
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Variable_name Value
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Feature_custom_aggregate_functions 2
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explain
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select * from t1, (select sal as a from t1 where (select f1(t3.sal) from t3) >=-1 ) q where q.a=t1.sal;
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 3
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1 PRIMARY t1 ALL NULL NULL NULL NULL 3 Using where; Using join buffer (flat, BNL join)
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3 SUBQUERY t3 ALL NULL NULL NULL NULL 4
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show status like "%custom_aggregate%";
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Variable_name Value
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Feature_custom_aggregate_functions 3
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explain
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select (select f1(sal) as a from t3 where t3.id= t1.id ) from t1 ;
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 3
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2 DEPENDENT SUBQUERY t3 ALL NULL NULL NULL NULL 4 Using where
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show status like "%custom_aggregate%";
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Variable_name Value
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Feature_custom_aggregate_functions 4
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explain
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select (select f1(sal) as a from t3 where t3.id= t1.id ) from t1 ;
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 3
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2 DEPENDENT SUBQUERY t3 ALL NULL NULL NULL NULL 4 Using where
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show status like "%custom_aggregate%";
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Variable_name Value
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Feature_custom_aggregate_functions 5
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custom aggregates inside other customm aggregates
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explain
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select f2(sal) from t1;
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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 3
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show status like "%custom_aggregate%";
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Variable_name Value
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Feature_custom_aggregate_functions 6
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cte with custom aggregates
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with agg_sum as (
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select f1(sal) from t1 where t1.id >=1 group by t1.id
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)
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select * from agg_sum;
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f1(sal)
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5000
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2000
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1000
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show status like "%custom_aggregate%";
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Variable_name Value
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Feature_custom_aggregate_functions 7
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drop table t2,t1,t3;
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drop function f1;
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drop function f2;
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