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MCOL-4234: improve GROUP BY and ORDER BY interaction (#3194)

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This patch fixes the problem in MCOL-4234 and also generally improves
behavior of GROUP BY.

It does so by introducing a "dummy" aggregate and by wrapping columns
into it. This allows for columns that are not in GROUP BY to be used
more freely, for example, in SELECT * FROM tbl GROUP BY col - all
columns that are not "col" will be wrapped into an aggregate and query
will proceed to execution.

The dummy aggregate itself does nothing more than remember last value
passed into it.

There also an additional error message that tries to explain what types
of expressions can be wrapped into an aggregate.
This commit is contained in:
Sergey Zefirov
2024-06-17 20:00:54 +03:00
committed by GitHub
parent b1045d27b6
commit 1122b64cb1
16 changed files with 312 additions and 25 deletions
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4
mysql-test/columnstore/basic/r/mcs76_having.result
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@ -23,7 +23,9 @@ col1 col2
3 sss
4 ooo
SELECT col1, col2, SUM(LENGTH(col2)) FROM t1 GROUP BY col1 HAVING col1 > 1 AND col2 LIKE '%o%' ORDER BY col1;
ERROR HY000: Internal error: MCS-2021: '`mcs76_db`.`t1`.`col2`' is not in GROUP BY clause. All non-aggregate columns in the SELECT and ORDER BY clause must be included in the GROUP BY clause.
col1 col2 SUM(LENGTH(col2))
2 oooooooooooooooooooo 40
4 ooo 6
CREATE TABLE t2(col1 INT, col2 DATETIME)ENGINE=Columnstore;
INSERT INTO t2 VALUES(1, '2020-2-2'),(2, '2020-3-3'),(5,'2020-6-6'),(6, '2020-7-7');
SELECT t1.col1, SUM(t1.col1*t2.col1) AS a FROM t1 JOIN t2 ON t1.col1 = t2.col1 GROUP BY t1.col1 HAVING a>1 ORDER BY t1.col1;