---
{
    "title": "ALTER-TABLE-ROLLUP",
    "language": "en"
}
---

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## ALTER-TABLE-ROLLUP

### Name

ALTER TABLE ROLLUP

### Description

This statement is used to perform a rollup modification operation on an existing table. The rollup is an asynchronous operation, and the task is returned when the task is submitted successfully. After that, you can use the [SHOW ALTER](../../Show-Statements/SHOW-ALTER.md) command to view the progress.

grammar:

```sql
ALTER TABLE [database.]table alter_clause;
```

The alter_clause of rollup supports the following creation methods

1. Create a rollup index

grammar:

```sql
ADD ROLLUP rollup_name (column_name1, column_name2, ...)
[FROM from_index_name]
[PROPERTIES ("key"="value", ...)]
```

2. Create rollup indexes in batches

grammar:

```sql
ADD ROLLUP [rollup_name (column_name1, column_name2, ...)
                    [FROM from_index_name]
                    [PROPERTIES ("key"="value", ...)],...]
```

Notice:

- If from_index_name is not specified, it will be created from base index by default
- Columns in rollup table must be columns already in from_index
- In properties, the storage format can be specified. For details, see [CREATE TABLE](../Create/CREATE-TABLE.html#create-table)

3. Delete rollup index

 grammar:

```sql
DROP ROLLUP rollup_name [PROPERTIES ("key"="value", ...)]
```

4. Batch delete rollup index

grammar:

```sql
DROP ROLLUP [rollup_name [PROPERTIES ("key"="value", ...)],...]
```

Notice:

- cannot delete base index

### Example

1. Create index: example_rollup_index, based on base index (k1,k2,k3,v1,v2). Columnar storage.

```sql
ALTER TABLE example_db.my_table
ADD ROLLUP example_rollup_index(k1, k3, v1, v2);
```

2. Create index: example_rollup_index2, based on example_rollup_index (k1,k3,v1,v2)

```sql
ALTER TABLE example_db.my_table
ADD ROLLUP example_rollup_index2 (k1, v1)
FROM example_rollup_index;
```

3. Create index: example_rollup_index3, based on base index (k1,k2,k3,v1), with a custom rollup timeout of one hour.

```sql
ALTER TABLE example_db.my_table
ADD ROLLUP example_rollup_index(k1, k3, v1)
PROPERTIES("timeout" = "3600");
```

4. Delete index: example_rollup_index2

```sql
ALTER TABLE example_db.my_table
DROP ROLLUP example_rollup_index2;
```

### Keywords

```text
ALTER, TABLE, ROLLUP
```

### Best Practice