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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.
46 lines
1.0 KiB
Plaintext
46 lines
1.0 KiB
Plaintext
DROP DATABASE IF EXISTS mcs286_db;
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CREATE DATABASE mcs286_db;
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USE mcs286_db;
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CREATE TABLE t1 (a INT, b CHAR(15))ENGINE=Columnstore;
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INSERT INTO t1 VALUES (NULL, NULL),(1, 'mariadb'),(2, 'columnstore'),(3, 'Innodb');
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SELECT LEFT('mariadb cs', 7) FROM t1 LIMIT 1;
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LEFT('mariadb cs', 7)
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mariadb
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SELECT LEFT('mariadb cs', 8) FROM t1 LIMIT 1;
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LEFT('mariadb cs', 8)
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mariadb
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SELECT LEFT('mariadb cs', 9) FROM t1 LIMIT 1;
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LEFT('mariadb cs', 9)
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mariadb c
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SELECT b, LEFT(b, 0) FROM t1 ORDER BY 1;
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b LEFT(b, 0)
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NULL NULL
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columnstore
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Innodb
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mariadb
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SELECT b, LEFT(b, -1) FROM t1 ORDER BY 1;
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b LEFT(b, -1)
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NULL NULL
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columnstore
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Innodb
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mariadb
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SELECT b, LEFT(b, 6) FROM t1 ORDER BY 1;
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b LEFT(b, 6)
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NULL NULL
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columnstore column
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Innodb Innodb
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mariadb mariad
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SELECT b, LEFT(b, 9) FROM t1 ORDER BY 1;
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b LEFT(b, 9)
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NULL NULL
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columnstore columnsto
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Innodb Innodb
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mariadb mariadb
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SELECT b, LEFT(concat('mmm_', b), 10) FROM t1 ORDER BY 1;
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b LEFT(concat('mmm_', b), 10)
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NULL NULL
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columnstore mmm_column
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Innodb mmm_Innodb
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mariadb mmm_mariad
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DROP DATABASE mcs286_db;
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