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Limit calculated rows to the number of rows in the table
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The result file changes are mainly that number of rows is one smaller
for some queries with DISTINCT or GROUP BY
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@montywi @spetrunia
montywi authored and spetrunia committed Jan 30, 2023
1 parent c443dbf commit 87d4d72
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Showing 12 changed files with 43 additions and 37 deletions.
6 changes: 3 additions & 3 deletions mysql-test/main/distinct.result
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Expand Up @@ -538,10 +538,10 @@ PRIMARY KEY (a,b));
INSERT INTO t2 VALUES (1,1,1,50), (1,2,3,40), (2,1,3,4);
EXPLAIN SELECT DISTINCT a FROM t2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 range NULL PRIMARY 4 NULL 4 Using index for group-by
1 SIMPLE t2 range NULL PRIMARY 4 NULL 3 Using index for group-by
EXPLAIN SELECT DISTINCT a,a FROM t2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 range NULL PRIMARY 4 NULL 4 Using index for group-by
1 SIMPLE t2 range NULL PRIMARY 4 NULL 3 Using index for group-by
EXPLAIN SELECT DISTINCT b,a FROM t2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 index NULL PRIMARY 8 NULL 3 Using index
Expand Down Expand Up @@ -756,7 +756,7 @@ INSERT INTO t1(a, b, c) VALUES (1, 1, 1),
(1, 2, 3);
EXPLAIN SELECT DISTINCT a, b, d, c FROM t1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range NULL PRIMARY 16 NULL 7 Using index for group-by; Using temporary
1 SIMPLE t1 range NULL PRIMARY 16 NULL 6 Using index for group-by; Using temporary
SELECT DISTINCT a, b, d, c FROM t1;
a b d c
1 1 0 1
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2 changes: 1 addition & 1 deletion mysql-test/main/explain_innodb.result
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Expand Up @@ -15,6 +15,6 @@ explain
SELECT * FROM (SELECT id FROM t1 GROUP BY id) dt WHERE 1=0;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE
2 DERIVED t1 range NULL id 53 NULL 2 Using index for group-by
2 DERIVED t1 range NULL id 53 NULL 1 Using index for group-by
SET GLOBAL slow_query_log = @sql_tmp;
drop table t1;
4 changes: 2 additions & 2 deletions mysql-test/main/group_by.result
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Expand Up @@ -1578,7 +1578,7 @@ id select_type table type possible_keys key key_len ref rows Extra
EXPLAIN SELECT a FROM t1 FORCE INDEX FOR JOIN (i2)
FORCE INDEX FOR GROUP BY (i2) GROUP BY a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range NULL i2 4 NULL 145 Using index for group-by
1 SIMPLE t1 range NULL i2 4 NULL 144 Using index for group-by
EXPLAIN SELECT a FROM t1 USE INDEX () IGNORE INDEX (i2);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 144
Expand Down Expand Up @@ -1701,7 +1701,7 @@ NULL 1
1 2
EXPLAIN SELECT a from t2 GROUP BY a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 range NULL a 5 NULL 7 Using index for group-by
1 SIMPLE t2 range NULL a 5 NULL 6 Using index for group-by
SELECT a from t2 GROUP BY a;
a
NULL
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2 changes: 1 addition & 1 deletion mysql-test/main/group_min_max.result
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Expand Up @@ -3664,7 +3664,7 @@ f1 COUNT(DISTINCT f2)
3 4
explain SELECT f1, COUNT(DISTINCT f2) FROM t1 GROUP BY f1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range NULL f1 5 NULL 9 Using index for group-by
1 SIMPLE t1 range NULL f1 5 NULL 8 Using index for group-by
drop table t1;
# End of test#50539.
#
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32 changes: 16 additions & 16 deletions mysql-test/main/opt_trace.result
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Expand Up @@ -1408,7 +1408,7 @@ test.t1 analyze status Engine-independent statistics collected
test.t1 analyze status OK
EXPLAIN SELECT MIN(d) FROM t1 where b=2 and c=3 group by a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range NULL a 20 NULL 8 Using where; Using index for group-by
1 SIMPLE t1 range NULL a 20 NULL 7 Using where; Using index for group-by
select * from information_schema.OPTIMIZER_TRACE;
QUERY TRACE MISSING_BYTES_BEYOND_MAX_MEM_SIZE INSUFFICIENT_PRIVILEGES
EXPLAIN SELECT MIN(d) FROM t1 where b=2 and c=3 group by a {
Expand Down Expand Up @@ -1495,8 +1495,8 @@ EXPLAIN SELECT MIN(d) FROM t1 where b=2 and c=3 group by a {
"index": "a",
"covering": true,
"ranges": ["(2,3) <= (b,c) <= (2,3)"],
"rows": 8,
"cost": 2.2
"rows": 7,
"cost": 2.05
}
]
},
Expand All @@ -1507,8 +1507,8 @@ EXPLAIN SELECT MIN(d) FROM t1 where b=2 and c=3 group by a {
"min_aggregate": true,
"max_aggregate": false,
"distinct_aggregate": false,
"rows": 8,
"cost": 2.2,
"rows": 7,
"cost": 2.05,
"key_parts_used_for_access": ["a", "b", "c"],
"ranges": ["(2,3) <= (b,c) <= (2,3)"],
"chosen": true
Expand All @@ -1521,13 +1521,13 @@ EXPLAIN SELECT MIN(d) FROM t1 where b=2 and c=3 group by a {
"min_aggregate": true,
"max_aggregate": false,
"distinct_aggregate": false,
"rows": 8,
"cost": 2.2,
"rows": 7,
"cost": 2.05,
"key_parts_used_for_access": ["a", "b", "c"],
"ranges": ["(2,3) <= (b,c) <= (2,3)"]
},
"rows_for_plan": 8,
"cost_for_plan": 2.2,
"rows_for_plan": 7,
"cost_for_plan": 2.05,
"chosen": true
}
}
Expand All @@ -1545,16 +1545,16 @@ EXPLAIN SELECT MIN(d) FROM t1 where b=2 and c=3 group by a {
"considered_access_paths": [
{
"access_type": "index_merge",
"resulting_rows": 8,
"cost": 2.2,
"resulting_rows": 7,
"cost": 2.05,
"chosen": true,
"use_tmp_table": true
}
],
"chosen_access_method": {
"type": "index_merge",
"records": 8,
"cost": 2.2,
"records": 7,
"cost": 2.05,
"uses_join_buffering": false
}
}
Expand All @@ -1564,9 +1564,9 @@ EXPLAIN SELECT MIN(d) FROM t1 where b=2 and c=3 group by a {
{
"plan_prefix": [],
"table": "t1",
"rows_for_plan": 8,
"cost_for_plan": 3.8,
"cost_for_sorting": 8
"rows_for_plan": 7,
"cost_for_plan": 3.45,
"cost_for_sorting": 7
}
]
},
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6 changes: 3 additions & 3 deletions mysql-test/main/subselect_mat.result
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Expand Up @@ -1142,7 +1142,7 @@ a
explain extended
select a from t1 group by a having a in (select c from t2 where d >= 20);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 range NULL it1a 4 NULL 8 100.00 Using index for group-by
1 PRIMARY t1 range NULL it1a 4 NULL 7 100.00 Using index for group-by
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 7 100.00 Using where
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` group by `test`.`t1`.`a` having <expr_cache><`test`.`t1`.`a`>(<in_optimizer>(`test`.`t1`.`a`,`test`.`t1`.`a` in ( <materialize> (/* select#2 */ select `test`.`t2`.`c` from `test`.`t2` where `test`.`t2`.`d` >= 20 ), <primary_index_lookup>(`test`.`t1`.`a` in <temporary table> on distinct_key where `test`.`t1`.`a` = `<subquery2>`.`c`))))
Expand All @@ -1154,7 +1154,7 @@ create index iab on t1(a, b);
explain extended
select a from t1 group by a having a in (select c from t2 where d >= 20);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 range NULL it1a 4 NULL 8 100.00 Using index for group-by
1 PRIMARY t1 range NULL it1a 4 NULL 7 100.00 Using index for group-by
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 7 100.00 Using where
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` group by `test`.`t1`.`a` having <expr_cache><`test`.`t1`.`a`>(<in_optimizer>(`test`.`t1`.`a`,`test`.`t1`.`a` in ( <materialize> (/* select#2 */ select `test`.`t2`.`c` from `test`.`t2` where `test`.`t2`.`d` >= 20 ), <primary_index_lookup>(`test`.`t1`.`a` in <temporary table> on distinct_key where `test`.`t1`.`a` = `<subquery2>`.`c`))))
Expand All @@ -1166,7 +1166,7 @@ explain extended
select a from t1 group by a
having a in (select c from t2 where d >= some(select e from t3 where max(b)=e));
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 range NULL iab 4 NULL 8 100.00 Using index for group-by
1 PRIMARY t1 range NULL iab 4 NULL 7 100.00 Using index for group-by
2 DEPENDENT SUBQUERY t2 ALL NULL NULL NULL NULL 7 100.00 Using where
3 DEPENDENT SUBQUERY t3 ALL NULL NULL NULL NULL 4 100.00 Using where
Warnings:
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6 changes: 3 additions & 3 deletions mysql-test/main/subselect_sj_mat.result
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Expand Up @@ -1181,7 +1181,7 @@ a
explain extended
select a from t1 group by a having a in (select c from t2 where d >= 20);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 range NULL it1a 4 NULL 8 100.00 Using index for group-by
1 PRIMARY t1 range NULL it1a 4 NULL 7 100.00 Using index for group-by
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 7 100.00 Using where
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` group by `test`.`t1`.`a` having <expr_cache><`test`.`t1`.`a`>(<in_optimizer>(`test`.`t1`.`a`,`test`.`t1`.`a` in ( <materialize> (/* select#2 */ select `test`.`t2`.`c` from `test`.`t2` where `test`.`t2`.`d` >= 20 ), <primary_index_lookup>(`test`.`t1`.`a` in <temporary table> on distinct_key where `test`.`t1`.`a` = `<subquery2>`.`c`))))
Expand All @@ -1193,7 +1193,7 @@ create index iab on t1(a, b);
explain extended
select a from t1 group by a having a in (select c from t2 where d >= 20);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 range NULL it1a 4 NULL 8 100.00 Using index for group-by
1 PRIMARY t1 range NULL it1a 4 NULL 7 100.00 Using index for group-by
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 7 100.00 Using where
Warnings:
Note 1003 /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` group by `test`.`t1`.`a` having <expr_cache><`test`.`t1`.`a`>(<in_optimizer>(`test`.`t1`.`a`,`test`.`t1`.`a` in ( <materialize> (/* select#2 */ select `test`.`t2`.`c` from `test`.`t2` where `test`.`t2`.`d` >= 20 ), <primary_index_lookup>(`test`.`t1`.`a` in <temporary table> on distinct_key where `test`.`t1`.`a` = `<subquery2>`.`c`))))
Expand All @@ -1205,7 +1205,7 @@ explain extended
select a from t1 group by a
having a in (select c from t2 where d >= some(select e from t3 where max(b)=e));
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 range NULL iab 4 NULL 8 100.00 Using index for group-by
1 PRIMARY t1 range NULL iab 4 NULL 7 100.00 Using index for group-by
2 DEPENDENT SUBQUERY t2 ALL NULL NULL NULL NULL 7 100.00 Using where
3 DEPENDENT SUBQUERY t3 ALL NULL NULL NULL NULL 4 100.00 Using where
Warnings:
Expand Down
2 changes: 1 addition & 1 deletion mysql-test/suite/gcol/r/gcol_select_innodb.result
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Expand Up @@ -146,7 +146,7 @@ count(distinct c)
3
explain select count(distinct c) from t1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range NULL c 5 NULL 6 Using index for group-by
1 SIMPLE t1 range NULL c 5 NULL 5 Using index for group-by
###
### filesort & range-based utils
###
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2 changes: 1 addition & 1 deletion mysql-test/suite/gcol/r/gcol_select_myisam.result
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Expand Up @@ -146,7 +146,7 @@ count(distinct c)
3
explain select count(distinct c) from t1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range NULL c 5 NULL 6 Using index for group-by
1 SIMPLE t1 range NULL c 5 NULL 5 Using index for group-by
###
### filesort & range-based utils
###
Expand Down
2 changes: 1 addition & 1 deletion mysql-test/suite/vcol/r/vcol_select_innodb.result
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Expand Up @@ -135,7 +135,7 @@ count(distinct c)
3
explain select count(distinct c) from t1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range NULL c 5 NULL 6 Using index for group-by
1 SIMPLE t1 range NULL c 5 NULL 5 Using index for group-by
###
### filesort & range-based utils
###
Expand Down
2 changes: 1 addition & 1 deletion mysql-test/suite/vcol/r/vcol_select_myisam.result
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Original file line number Diff line number Diff line change
Expand Up @@ -133,7 +133,7 @@ count(distinct c)
3
explain select count(distinct c) from t1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range NULL c 5 NULL 6 Using index for group-by
1 SIMPLE t1 range NULL c 5 NULL 5 Using index for group-by
###
### filesort & range-based utils
###
Expand Down
14 changes: 10 additions & 4 deletions sql/opt_range.cc
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Expand Up @@ -3235,7 +3235,7 @@ double records_in_column_ranges(PARAM *param, uint idx,
SEL_ARG_RANGE_SEQ seq;
KEY_MULTI_RANGE range;
range_seq_t seq_it;
double rows;
double rows, table_records;
Field *field;
uint flags= 0;
double total_rows= 0;
Expand Down Expand Up @@ -3290,13 +3290,17 @@ double records_in_column_ranges(PARAM *param, uint idx,
total_rows= DBL_MAX;
break;
}
total_rows += rows;
total_rows+= rows;
}
if (total_rows == 0)
total_rows= MY_MIN(1, rows2double(param->table->stat_records()));

return total_rows;
}
table_records= rows2double(param->table->stat_records());
if (total_rows > table_records)
DBUG_PRINT("error", ("table_records: %g < total_records: %g",
table_records, total_rows));
return MY_MIN(total_rows, table_records);
}


/*
Expand Down Expand Up @@ -14813,6 +14817,8 @@ void cost_group_min_max(TABLE* table, KEY *index_info, uint used_key_parts,
num_groups= (ha_rows) rint(num_groups * quick_prefix_selectivity);
set_if_bigger(num_groups, 1);
}
/* Ensure we don't have more groups than rows in table */
set_if_smaller(num_groups, table_records);

if (used_key_parts > group_key_parts)
{ /*
Expand Down

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