DOCSUP-3122: Document two expressions ALTER #17059
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robot-clickhouse
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AnaUvarova
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BayoNet
reviewed
Dec 15, 2020
AnaUvarova
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olgarev
reviewed
Dec 18, 2020
| ``` | ||
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| ## REMOVE TTL {remove-ttl} | ||
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"#" missed in anchor. Should be {#remove-ttl}
olgarev
reviewed
Dec 18, 2020
| @@ -122,6 +122,26 @@ Example: | |||
| ALTER TABLE visits MODIFY COLUMN browser Array(String) | |||
| ``` | |||
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| ## MODIFY REMOVE | |||
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olgarev
reviewed
Dec 18, 2020
| @@ -110,6 +110,25 @@ MODIFY COLUMN [IF EXISTS] name [type] [default_expr] [TTL] | |||
| ``` sql | |||
| ALTER TABLE visits MODIFY COLUMN browser Array(String) | |||
| ``` | |||
| ## MODIFY REMOVE | |||
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olgarev
reviewed
Dec 18, 2020
| Вы можете изменить [TTL для таблицы](../../../engines/table-engines/mergetree-family/mergetree.md#mergetree-column-ttl) запросом следующего вида: | ||
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| ``` sql | ||
| ALTER TABLE table-name MODIFY TTL ttl-expression | ||
| ``` | ||
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| ## REMOVE TTL {remove-ttl} | ||
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There was a problem hiding this comment.
"#" missed in anchor. Should be {#remove-ttl}
alesapin
requested changes
Dec 22, 2020
| @@ -122,6 +122,26 @@ Example: | |||
| ALTER TABLE visits MODIFY COLUMN browser Array(String) | |||
| ``` | |||
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| ## MODIFY REMOVE | |||
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| Removes something from a column. For example, TTL-property. | |||
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Removes one of column properties: DEFAULT, ALIAS, MATERIALIZED, CODEC, COMMENT, TTL. We have to list all of them.
| To start the background cleaning using TTL, make this: | ||
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| ```sql | ||
| OPTIMIZE TABLE table_with_ttl FINAL; |
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No table definition and now info about data. How reader can guess it?
| And now we have nothing to delete. | ||
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| ```text | ||
| --2020-12-11 12:44:57 1 username1 |
| As a result you see that the second line was deleted. | ||
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| ```text | ||
| 2020-12-11 12:44:57 1 username1 |
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Need formatted output, not tab separated.
| ``` | ||
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| And now we have nothing to delete. |
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Now TTL removed and nothing will be deleted.
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| Requests and results: | ||
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| To start the background cleaning using TTL, make this: |
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Trigger TTL forcefully with OPTIMIZE query.
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@alesapin |
alesapin
approved these changes
Jan 12, 2021
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