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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
This commit is contained in:
Monty
2021-10-06 02:39:59 +03:00
committed by Sergei Petrunia
parent c443dbff0e
commit 87d4d7232c
12 changed files with 43 additions and 37 deletions
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6
mysql-test/main/distinct.result
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@ -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
@ -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