mirror of
https://github.com/mariadb-corporation/mariadb-columnstore-engine.git
synced 2025-04-18 21:44:02 +03:00
b53c231ca6
This patch improves handling of NULLs in textual fields in ColumnStore. Previously empty strings were considered NULLs and it could be a problem if data scheme allows for empty strings. It was also one of major reasons of behavior difference between ColumnStore and other engines in MariaDB family. Also, this patch fixes some other bugs and incorrect behavior, for example, incorrect comparison for "column <= ''" which evaluates to constant True for all purposes before this patch.
90 lines
3.6 KiB
Plaintext
90 lines
3.6 KiB
Plaintext
DROP DATABASE IF EXISTS mcs91_db;
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CREATE DATABASE mcs91_db;
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USE mcs91_db;
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CREATE TABLE t1
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(
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t1_int INT,
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t1_decimal DECIMAL(5,2),
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t1_text TEXT,
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t1_char CHAR(1),
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t1_datetime DATETIME
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)ENGINE=Columnstore;
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INSERT INTO t1 VALUES(NULL, NULL, NULL, NULL, '0000-00-00');
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INSERT INTO t1 VALUES(123456, 111.11, repeat('a',10), 'a', '1111-11-11 11:11:11');
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INSERT INTO t1 VALUES(NULL, 222.22, '', 'b', '2222-12-22 22:22:22');
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SELECT *, COALESCE(t1_int, 'No Value') FROM t1 ORDER BY t1_int;
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t1_int t1_decimal t1_text t1_char t1_datetime COALESCE(t1_int, 'No Value')
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NULL NULL NULL NULL 0000-00-00 00:00:00 No Value
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NULL 222.22 b 2222-12-22 22:22:22 No Value
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123456 111.11 aaaaaaaaaa a 1111-11-11 11:11:11 123456
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SELECT *, COALESCE(t1_decimal, 'No Value') FROM t1 ORDER BY t1_int;
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t1_int t1_decimal t1_text t1_char t1_datetime COALESCE(t1_decimal, 'No Value')
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NULL NULL NULL NULL 0000-00-00 00:00:00 No Value
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NULL 222.22 b 2222-12-22 22:22:22 222.22
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123456 111.11 aaaaaaaaaa a 1111-11-11 11:11:11 111.11
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SELECT *, COALESCE(t1_text, 'No Value') FROM t1 ORDER BY t1_int;
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t1_int t1_decimal t1_text t1_char t1_datetime COALESCE(t1_text, 'No Value')
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NULL NULL NULL NULL 0000-00-00 00:00:00 No Value
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NULL 222.22 b 2222-12-22 22:22:22
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123456 111.11 aaaaaaaaaa a 1111-11-11 11:11:11 aaaaaaaaaa
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SELECT *, COALESCE(t1_datetime, 'No Value') FROM t1 ORDER BY t1_int;
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t1_int t1_decimal t1_text t1_char t1_datetime COALESCE(t1_datetime, 'No Value')
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NULL NULL NULL NULL 0000-00-00 00:00:00 0000-00-00 00:00:00
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NULL 222.22 b 2222-12-22 22:22:22 2222-12-22 22:22:22
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123456 111.11 aaaaaaaaaa a 1111-11-11 11:11:11 1111-11-11 11:11:11
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SELECT t1_int, t1_decimal, COALESCE(t1_text, LEFT(t1_char,10)) FROM t1 ORDER BY t1_int;
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t1_int t1_decimal COALESCE(t1_text, LEFT(t1_char,10))
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NULL NULL NULL
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NULL 222.22
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123456 111.11 aaaaaaaaaa
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SELECT t1_int, LEAST(t1_int, t1_decimal) FROM t1 ORDER BY 1;
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t1_int LEAST(t1_int, t1_decimal)
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NULL NULL
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NULL NULL
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123456 111.11
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SELECT t1_int, LEAST(t1_int, t1_decimal, t1_text) FROM t1 ORDER BY 1;
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t1_int LEAST(t1_int, t1_decimal, t1_text)
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NULL NULL
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NULL NULL
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123456 0
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SELECT t1_int, LEAST(t1_int, t1_decimal, t1_text, t1_datetime) FROM t1 ORDER BY 1;
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t1_int LEAST(t1_int, t1_decimal, t1_text, t1_datetime)
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NULL NULL
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NULL NULL
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123456 0000-00-00 00:00:00.000000
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SELECT t1_int, GREATEST(t1_int, t1_decimal) FROM t1 ORDER BY 1;
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t1_int GREATEST(t1_int, t1_decimal)
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NULL NULL
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NULL NULL
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123456 123456.00
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SELECT t1_int, GREATEST(t1_int, t1_decimal, t1_text) FROM t1 ORDER BY 1;
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t1_int GREATEST(t1_int, t1_decimal, t1_text)
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NULL NULL
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NULL NULL
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123456 123456
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SELECT t1_int, GREATEST(t1_int, t1_decimal, t1_text, t1_datetime) FROM t1 ORDER BY 1;
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t1_int GREATEST(t1_int, t1_decimal, t1_text, t1_datetime)
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NULL NULL
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NULL NULL
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123456 1111-11-11 11:11:11.000000
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SELECT t1_int, LEAST(IFNULL(t1_int, 0), IFNULL(t1_decimal, 0), IFNULL(t1_text, 'no value'), IFNULL(t1_datetime, '0')) least,
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GREATEST(IFNULL(t1_int, 0), IFNULL(t1_decimal, 0), IFNULL(t1_text, 0), IFNULL(t1_datetime, 0)) highest
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FROM t1 ORDER BY 2;
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t1_int least highest
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NULL 0 0
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123456 0 3.129152848233759e17
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NULL 0 6.256546477863076e17
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SELECT * FROM t1 WHERE ISNULL(t1_int) ORDER BY t1_decimal;
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t1_int t1_decimal t1_text t1_char t1_datetime
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NULL NULL NULL NULL 0000-00-00 00:00:00
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NULL 222.22 b 2222-12-22 22:22:22
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SELECT * FROM t1 WHERE ISNULL(t1_decimal) ORDER BY t1_decimal;
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t1_int t1_decimal t1_text t1_char t1_datetime
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NULL NULL NULL NULL 0000-00-00 00:00:00
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SELECT * FROM t1 WHERE ISNULL(t1_text) ORDER BY t1_decimal;
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t1_int t1_decimal t1_text t1_char t1_datetime
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NULL NULL NULL NULL 0000-00-00 00:00:00
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SELECT * FROM t1 WHERE ISNULL(t1_datetime) ORDER BY t1_decimal;
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t1_int t1_decimal t1_text t1_char t1_datetime
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DROP DATABASE mcs91_db;
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