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cfa9a7ff2c
* feat(optimizer): MCOL-5250 rewrite queries with DISTINCT
... as aggregated queries.
So query
```
SELECT DISTINCT <cols list>
FROM <from list>
WHERE <where clause>
HAVING <having clause>
ORDER BY <orderby list>
LIMIT <limit>
```
will become
```
SELECT *
FROM
(
SELECT <cols list>
FROM <from list>
WHERE <where clause>
HAVING <having clause>
) a
GROUP BY 1,2,3,...,N
ORDER BY <orderby list>
LIMIT limit
```
* move ORDER BY to the outer query
* fix test
* reuse cloneWORecursiveSelects() in clone()
* fix subselect columns processing
57 lines
887 B
Plaintext
57 lines
887 B
Plaintext
DROP DATABASE IF EXISTS mcs37_db;
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CREATE DATABASE mcs37_db;
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USE mcs37_db;
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CREATE TABLE t1(col1 INT, col2 CHAR(5))ENGINE=Columnstore;
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INSERT INTO t1 VALUES(NULL, NULL),(1,'a'),(1,'b'),(1,'c'),(2,'dd'),(3,'eee');
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SELECT COUNT(DISTINCT col1) FROM t1;
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COUNT(DISTINCT col1)
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3
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SELECT COUNT(DISTINCT col2) FROM t1;
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COUNT(DISTINCT col2)
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5
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SELECT DISTINCT col1 FROM t1;
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col1
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1
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2
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3
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NULL
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SELECT DISTINCT col1 FROM t1 ORDER BY col1 DESC;
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col1
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3
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2
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1
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NULL
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SELECT DISTINCT col2 FROM t1;
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col2
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NULL
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a
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b
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c
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dd
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eee
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CREATE TABLE t2(col1 INT)ENGINE=Columnstore;
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INSERT INTO t2 SELECT DISTINCT col1 FROM t1;
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SELECT * FROM t2;
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col1
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1
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2
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3
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NULL
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CREATE TABLE t3 (name varchar(255));
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INSERT INTO t3 VALUES ('aa'),('ab'),('ac'),('ad'),('ae');
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SELECT DISTINCT * FROM t3;
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name
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aa
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ab
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ac
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ad
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ae
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SELECT DISTINCT name FROM t3 ORDER BY name LIMIT 2;
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name
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aa
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ab
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SELECT DISTINCT 1 FROM t3 LIMIT 3;
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1
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1
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DROP DATABASE mcs37_db;
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