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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.
56 lines
1.1 KiB
Plaintext
56 lines
1.1 KiB
Plaintext
DROP DATABASE IF EXISTS mcs222_db;
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CREATE DATABASE mcs222_db;
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USE mcs222_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, 'a'),(2, 'aqaaqq'),(3, 'cqcqqcq'),(4, 'qdqdqqdq'),(5, 'aaaqq');
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SELECT POSITION('zz' IN 'aazazazapq');
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POSITION('zz' IN 'aazazazapq')
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0
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SELECT POSITION('zz' IN 'zzaazapq');
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POSITION('zz' IN 'zzaazapq')
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1
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SELECT POSITION('zz' IN 'aazzzazzaq');
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POSITION('zz' IN 'aazzzazzaq')
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3
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SELECT b, POSITION('a' IN b) FROM t1 ORDER BY b;
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b POSITION('a' IN b)
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NULL NULL
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a 1
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aaaqq 1
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aqaaqq 1
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cqcqqcq 0
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qdqdqqdq 0
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SELECT b, POSITION('aa' IN b) FROM t1 ORDER BY b;
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b POSITION('aa' IN b)
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NULL NULL
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a 0
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aaaqq 1
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aqaaqq 3
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cqcqqcq 0
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qdqdqqdq 0
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SELECT b, POSITION('aaa' IN b) FROM t1 ORDER BY b;
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b POSITION('aaa' IN b)
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NULL NULL
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a 0
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aaaqq 1
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aqaaqq 0
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cqcqqcq 0
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qdqdqqdq 0
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SELECT b, POSITION('qq' IN b) FROM t1 ORDER BY b;
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b POSITION('qq' IN b)
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NULL NULL
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a 0
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aaaqq 4
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aqaaqq 5
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cqcqqcq 4
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qdqdqqdq 5
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SELECT b, POSITION(concat(b, 'zzz') IN 'azzzghijk') FROM t1 ORDER BY b;
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b POSITION(concat(b, 'zzz') IN 'azzzghijk')
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NULL NULL
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a 1
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aaaqq 0
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aqaaqq 0
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cqcqqcq 0
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qdqdqqdq 0
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DROP DATABASE mcs222_db;
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