mirror of
https://github.com/mariadb-corporation/mariadb-columnstore-engine.git
synced 2025-05-02 19:24:47 +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.
54 lines
1.8 KiB
Plaintext
54 lines
1.8 KiB
Plaintext
DROP DATABASE IF EXISTS mcs174_db;
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CREATE DATABASE mcs174_db;
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USE mcs174_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 b, c, (CASE WHEN a = 'b' THEN b ELSE c END) FROM t1;
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b c (CASE WHEN a = 'b' THEN b ELSE c END)
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NULL 0000-00-00 00:00:00 0000-00-00 00:00:00
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12 1212-12-12 00:00:00 1212-12-12 00:00:00
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13 1313-03-13 13:13:13 13
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14 1414-04-14 00:00:00 1414-04-14 00:00:00
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15 2015-05-15 15:15:15 2015-05-15 15:15:15
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SELECT b, a, (CASE WHEN b > 13 THEN b ELSE a END) FROM t1;
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b a (CASE WHEN b > 13 THEN b ELSE a END)
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NULL NULL NULL
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12 a a
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13 b b
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14 c 14
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15 d 15
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SELECT c, a, (CASE WHEN d > 1 THEN a ELSE c END) FROM t1;
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c a (CASE WHEN d > 1 THEN a ELSE c END)
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0000-00-00 00:00:00 NULL 0000-00-00 00:00:00
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1212-12-12 00:00:00 a a
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1313-03-13 13:13:13 b b
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1414-04-14 00:00:00 c 1414-04-14 00:00:00
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2015-05-15 15:15:15 d d
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SELECT a, c, (CASE WHEN c IS NULL THEN a ELSE c END) FROM t1;
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a c (CASE WHEN c IS NULL THEN a ELSE c END)
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NULL 0000-00-00 00:00:00 0000-00-00 00:00:00
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a 1212-12-12 00:00:00 1212-12-12 00:00:00
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b 1313-03-13 13:13:13 1313-03-13 13:13:13
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c 1414-04-14 00:00:00 1414-04-14 00:00:00
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d 2015-05-15 15:15:15 2015-05-15 15:15:15
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SELECT (CASE WHEN a = 'a' THEN 0 ELSE 1 END) FROM t1;
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(CASE WHEN a = 'a' THEN 0 ELSE 1 END)
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1
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0
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1
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1
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1
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SELECT (CASE WHEN 10 > 5 THEN 'True' ELSE 'False' END);
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(CASE WHEN 10 > 5 THEN 'True' ELSE 'False' END)
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True
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DROP DATABASE mcs174_db;
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