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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.
43 lines
1.2 KiB
Plaintext
43 lines
1.2 KiB
Plaintext
DROP DATABASE IF EXISTS mcs173_db;
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CREATE DATABASE mcs173_db;
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USE mcs173_db;
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SET default_storage_engine=Columnstore;
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CREATE TABLE t1 (a CHAR(1), b INT, c DATETIME, d DOUBLE);
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INSERT INTO t1 VALUES (NULL, NULL, '0-0-0', NULL),('a', 12, '1212-12-12', 1.19691E+100),('b', 13, '1313-3-13 13:13:13', 2.1961E+18),('c', 14, '1414-4-14', 0.16191),('d', 15, '2015-5-15 15:15:15', 1.971917);
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SHOW CREATE TABLE t1;
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Table Create Table
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t1 CREATE TABLE `t1` (
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`a` char(1) DEFAULT NULL,
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`b` int(11) DEFAULT NULL,
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`c` datetime DEFAULT NULL,
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`d` double DEFAULT NULL
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) ENGINE=Columnstore DEFAULT CHARSET=latin1
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SELECT COALESCE(NULL, NULL, NULL, 'mariadb', NULL, 'columnstore');
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COALESCE(NULL, NULL, NULL, 'mariadb', NULL, 'columnstore')
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mariadb
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SELECT COALESCE(NULL, 1, 2, 'columnstore');
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COALESCE(NULL, 1, 2, 'columnstore')
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1
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SELECT a, COALESCE(a, 'na') FROM t1;
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a COALESCE(a, 'na')
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NULL na
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a a
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b b
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c c
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d d
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SELECT b, COALESCE(b, 'null value') FROM t1;
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b COALESCE(b, 'null value')
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NULL null value
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12 12
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13 13
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14 14
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15 15
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SELECT d, COALESCE(d, 'null value') FROM t1;
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d COALESCE(d, 'null value')
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NULL null value
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1.19691e100 1.19691e100
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2.1961e18 2.1961e18
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0.16191 0.16191
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1.971917 1.971917
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DROP DATABASE mcs173_db;
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