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27 lines
1.2 KiB
SQL
27 lines
1.2 KiB
SQL
DROP TABLE IF EXISTS column_modify_test;
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CREATE TABLE column_modify_test (id UInt64, val String, other_col UInt64) engine=MergeTree ORDER BY id SETTINGS min_bytes_for_wide_part=0;
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INSERT INTO column_modify_test VALUES (1,'one',0);
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INSERT INTO column_modify_test VALUES (2,'two',0);
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-- on 21.9 that was done via mutations mechanism
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ALTER TABLE column_modify_test MODIFY COLUMN val Nullable(String);
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-- but since 21.10 it only applies that to new part, so old parts keep the old schema
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--SELECT * FROM system.mutations;
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INSERT INTO column_modify_test VALUES (3,Null,0);
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--select name, path, type, active, modification_time from system.parts_columns where table='column_modify_test' and column='val';
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-- till now everythings looks ok
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--SELECT * FROM column_modify_test;
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-- now we do mutation. It will affect one of the parts
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-- and it what part it will update columns.txt to the latest 'correct' state w/o updating the column file!
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alter table column_modify_test update other_col=1 where id = 1 SETTINGS mutations_sync=1;
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-- row 1 is damaged now: the column files of val columns & columns.txt is out of sync!
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SELECT *, throwIf(val <> 'one') FROM column_modify_test WHERE id = 1 FORMAT CSV;
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