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32 lines
1.3 KiB
SQL
32 lines
1.3 KiB
SQL
DROP TABLE IF EXISTS t_modify_to_nullable;
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CREATE TABLE t_modify_to_nullable (key UInt64, id UInt64, s String)
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ENGINE = MergeTree ORDER BY id PARTITION BY key
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SETTINGS min_bytes_for_wide_part = 0, ratio_of_defaults_for_sparse_serialization = 0.9;
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INSERT INTO t_modify_to_nullable SELECT 1, number, 'foo' FROM numbers(10000);
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INSERT INTO t_modify_to_nullable SELECT 2, number, if (number % 23 = 0, 'bar', '') FROM numbers(10000);
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SELECT name, type, serialization_kind FROM system.parts_columns
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WHERE database = currentDatabase() AND table = 't_modify_to_nullable' AND column = 's' AND active
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ORDER BY name;
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SELECT count(s), countIf(s != ''), arraySort(groupUniqArray(s)) FROM t_modify_to_nullable;
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SET mutations_sync = 2;
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ALTER TABLE t_modify_to_nullable MODIFY COLUMN s Nullable(String);
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SELECT name, type, serialization_kind FROM system.parts_columns
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WHERE database = currentDatabase() AND table = 't_modify_to_nullable' AND column = 's' AND active
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ORDER BY name;
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SELECT count(s), countIf(s != ''), arraySort(groupUniqArray(s)) FROM t_modify_to_nullable;
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SYSTEM FLUSH LOGS;
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SELECT part_name, read_rows FROM system.part_log
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WHERE database = currentDatabase() AND table = 't_modify_to_nullable' AND event_type = 'MutatePart'
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ORDER BY part_name;
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DROP TABLE t_modify_to_nullable;
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