Details
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Bug
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Status: Closed (View Workflow)
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Major
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Resolution: Fixed
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10.2, 10.3
Description
Apparently InnoDB doesn't copy blob data during online ALTER TABLE. In a meanwhile it calls innobase_rec_reset(), which may reallocate memory for blobs.
It wasn't a problem before column compression was introduced, since in most (if not all) cases memory reallocation was not needed. With compressed columns reallocation is always there.
Grep for MDEV-12586 in source code for relevant markers. Re-enable online ALTER TABLE and run main.column_compression test.
Test not involving column compression:
CREATE TABLE t1(a INT) ENGINE=InnoDB;
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INSERT INTO t1 VALUES(1),(2),(3);
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ALTER TABLE t1 ADD COLUMN b TEXT DEFAULT REPEAT("a", 5*a);
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SELECT * FROM t1;
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a b
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1 NULL
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2 NULL
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3 NULL
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DROP TABLE t1;
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CREATE TABLE t1(a INT) ENGINE=MyISAM;
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INSERT INTO t1 VALUES(1),(2),(3);
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ALTER TABLE t1 ADD COLUMN b TEXT DEFAULT REPEAT("a", 5*a);
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SELECT * FROM t1;
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a b
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1 aaaaa
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2 aaaaaaaaaa
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3 aaaaaaaaaaaaaaa
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DROP TABLE t1;
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Attachments
Issue Links
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