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Update table.md

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EPHEMERAL specifier is added
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yakov-olkhovskiy 2022-02-08 11:35:14 -05:00 committed by GitHub
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docs/en/sql-reference/statements/create/table.md
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@ -16,8 +16,8 @@ By default, tables are created only on the current server. Distributed DDL queri
``` sql
CREATE TABLE [IF NOT EXISTS] [db.]table_name [ON CLUSTER cluster]
(
name1 [type1] [NULL|NOT NULL] [DEFAULT|MATERIALIZED|ALIAS expr1] [compression_codec] [TTL expr1],
name2 [type2] [NULL|NOT NULL] [DEFAULT|MATERIALIZED|ALIAS expr2] [compression_codec] [TTL expr2],
name1 [type1] [NULL|NOT NULL] [DEFAULT|MATERIALIZED|EPHEMERAL|ALIAS expr1] [compression_codec] [TTL expr1],
name2 [type2] [NULL|NOT NULL] [DEFAULT|MATERIALIZED|EPHEMERAL|ALIAS expr2] [compression_codec] [TTL expr2],
...
) ENGINE = engine
```
@ -112,6 +112,13 @@ Materialized expression. Such a column can’t be specified for INSERT, because
For an INSERT without a list of columns, these columns are not considered.
In addition, this column is not substituted when using an asterisk in a SELECT query. This is to preserve the invariant that the dump obtained using `SELECT *` can be inserted back into the table using INSERT without specifying the list of columns.
### EPHEMERAL {#ephemeral}
`EPHEMERAL expr`
Ephemeral column. Such a column isn't stored in the table and cannot be SELECTed, but can be referenced in the defaults of CREATE statement.
Currently SELECT/INSERT invariant is not preserved for this type, i.e. set of fields obtained using `SELECT *` cannot be inserted back into the table using INSERT without specifying the list of columns.
### ALIAS {#alias}
`ALIAS expr`