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> Use this file to discover all available pages before exploring further.
# ALTER MATERIALIZED VIEW (Continuous Aggregate)
> Change an existing continuous aggregate
export const PG = 'Postgres';
export const TIMESCALE_DB = 'TimescaleDB';
export const CHUNK = 'chunk';
export const COLUMNSTORE = 'columnstore';
export const HYPERTABLE = 'hypertable';
export const CAGG = 'continuous aggregate';
Since [1.3.0][tsdb-1.3.0]
You use the `ALTER MATERIALIZED VIEW` statement to modify some of the `WITH`
clause [options][create_materialized_view] for a {CAGG} view. You can only set the `continuous` and
`create_group_indexes` options when you [create a {CAGG}][create_materialized_view]. `ALTER MATERIALIZED VIEW` also
supports the following
[{PG} clauses][postgres-alterview] on the {CAGG} view:
* `RENAME TO`: rename the {CAGG} view
* `RENAME [COLUMN]`: rename the {CAGG} column
* `SET SCHEMA`: set the new schema for the {CAGG} view
* `SET TABLESPACE`: move the materialization of the {CAGG} view to the new tablespace
* `OWNER TO`: set a new owner for the {CAGG} view
## Samples
* Enable real-time aggregates for a {CAGG}:
```sql theme={"dark"}
ALTER MATERIALIZED VIEW contagg_view SET (timescaledb.materialized_only = false);
```
* Enable hypercore for a {CAGG}:
Since 2.18.0
```sql theme={"dark"}
ALTER MATERIALIZED VIEW contagg_view SET (
timescaledb.enable_columnstore = true,
timescaledb.segmentby = 'symbol' );
```
* Rename a column for a {CAGG}:
```sql theme={"dark"}
ALTER MATERIALIZED VIEW contagg_view RENAME COLUMN old_name TO new_name;
```
## Arguments
The syntax is:
```sql theme={"dark"}
ALTER MATERIALIZED VIEW SET ( timescaledb. = [, ... ] )
```
| Name | Type | Default | Required | Description |
| ------------------------------------------------------------------------- | -------- | ---------------------------------------------------- | -------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `view_name` | TEXT | - | ✔ | The name of the {CAGG} view to be altered. |
| `timescaledb.materialized_only` | BOOLEAN | `true` | - | Return only materialized data when querying the {CAGG} view. Set to `false` to enable real-time aggregation. |
| `timescaledb.enable_columnstore` | BOOLEAN | `true` | - | Enable {COLUMNSTORE}. Effectively the same as `timescaledb.compress`. Since 2.18.0 |
| `timescaledb.compress` | TEXT | Disabled | - | Enable compression. |
| `timescaledb.orderby` | TEXT | Descending order on the time column in `table_name`. | - | Set the order in which items are used in the {COLUMNSTORE}. Specified in the same way as an `ORDER BY` clause in a `SELECT` query. Since 2.18.0 |
| `timescaledb.compress_orderby` | TEXT | Descending order on the time column in `table_name`. | - | Set the order used by compression. Specified in the same way as the `ORDER BY` clause in a `SELECT` query. |
| `timescaledb.segmentby` | TEXT | No segmentation by column. | - | Set the list of columns used to segment data in the {COLUMNSTORE} for `table`. An identifier representing the source of the data such as `device_id` or `tags_id` is usually a good candidate. Since 2.18.0 |
| `timescaledb.compress_segmentby` | TEXT | No segmentation by column. | - | Set the list of columns used to segment the compressed data. An identifier representing the source of the data such as `device_id` or `tags_id` is usually a good candidate. |
| `column_name` | TEXT | - | - | Set the name of the column to order by or segment by. |
| `timescaledb.compress_chunk_time_interval` | TEXT | - | - | Reduce the total number of compressed/{COLUMNSTORE} {CHUNK}s for `table`. If you set `compress_chunk_time_interval`, compressed/{COLUMNSTORE} {CHUNK}s are merged with the previous adjacent {CHUNK} within `chunk_time_interval` whenever possible. These {CHUNK}s are irreversibly merged. If you call to [decompress][decompress]/[convert\_to\_rowstore][convert_to_rowstore], merged {CHUNK}s are not split up. You can call `compress_chunk_time_interval` independently of other compression settings; `timescaledb.compress`/`timescaledb.enable_columnstore` is not required. |
| `timescaledb.chunk_interval` (formerly `timescaledb.chunk_time_interval`) | INTERVAL | 10x the original {HYPERTABLE}. | - | Set the {CHUNK} interval. Renamed in {TIMESCALE_DB} V2.20. |
## Returns
For standard `ALTER MATERIALIZED VIEW` return behavior, see the [PostgreSQL ALTER MATERIALIZED VIEW documentation][postgres-alterview].
[convert_to_rowstore]: /api-reference/timescaledb/hypercore/convert_to_rowstore
[create-cagg]: /use-timescale/latest/continuous-aggregates/create-a-continuous-aggregate/
[create_materialized_view]: /api-reference/timescaledb/continuous-aggregates/create_materialized_view#arguments
[decompress]: /api-reference/timescaledb/hypercore/convert_to_rowstore
[default_table_access_method]: https://www.postgresql.org/docs/17/runtime-config-client.html#GUC-DEFAULT-TABLE-ACCESS-METHOD
[postgres-alterview]: https://www.postgresql.org/docs/current/sql-alterview.html
[tsdb-1.3.0]: https://github.com/timescale/timescaledb/releases/tag/1.3.0