ClickHouse/docs/en/operations/system-tables/projections.md

slug
/en/operations/system-tables/projections

projections

Contains information about existing projections in all the tables.

Columns:

• database (String) — Database name.
• table (String) — Table name.
• name (String) — Projection name.
• type (Enum) — Projection type ('Normal' = 0, 'Aggregate' = 1).
• sorting_key (Array(String)) — Projection sorting key.
• query (String) — Projection query.

Example

SELECT * FROM system.projections LIMIT 2 FORMAT Vertical;

Row 1:
──────
database:    default
table:       landing
name:        improved_sorting_key
type:        Normal
sorting_key: ['user_id','date']
query:       SELECT * ORDER BY user_id, date

Row 2:
──────
database:    default
table:       landing
name:        agg_no_key
type:        Aggregate
sorting_key: []
query:       SELECT count()