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Coordinator DB
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system.columns ​

Read-only metadata for columns across registered server databases. Use it to discover a table's declared schema rather than inferring a schema from its current values.

Columns ​

Name Meaning
database Managed database name.
table Table or view name; quote this identifier in SQL.
name Column name.
type Declared type text.
position One-based column position.
default_kind Kind of declared default or generated value.
default_expression SQL expression defining that value.
is_in_primary_key Whether the column is part of the primary key.
is_nullable Whether the column permits a top-level NULL.
primary_key_position Position in the declared key, or zero when absent.
schema_name Connection namespace, such as main or temp.
is_temporary Whether the object belongs to the observing temporary namespace.

Example ​

sql
CREATE TABLE documented_columns(id UInt32, label String);
sql
SELECT name, type, position
FROM system.columns
WHERE "table" = 'documented_columns' AND schema_name = 'main'
ORDER BY position
FORMAT csv;
text
"id","UInt32",1
"label","String",2

Always use the system qualifier. This service relation is provided by the server, rather than a standalone embedded connection. See system.tables for object-level metadata.