Amazon Redshift will no longer support the creation of new Python UDFs starting Patch 198. Existing Python UDFs will continue to function until June 30, 2026. For more information, see the [ blog post ](https://aws.amazon.com/blogs/big-data/amazon-redshift-python-user-defined-functions-will-reach-end-of-support-after-june-30-2026/). 

# SVV\_DISKUSAGE
<a name="r_SVV_DISKUSAGE"></a>

Amazon Redshift creates the SVV\_DISKUSAGE system view by joining the STV\_TBL\_PERM and STV\_BLOCKLIST tables. The SVV\_DISKUSAGE view contains information about data allocation for the tables in a database.

Use aggregate queries with SVV\_DISKUSAGE, as the following examples show, to determine the number of disk blocks allocated per database, table, slice, or column. Each data block uses 1 MB. You can also use [STV\_PARTITIONS](r_STV_PARTITIONS.md) to view summary information about disk utilization.

SVV\_DISKUSAGE is visible only to superusers. For more information, see [Visibility of data in system tables and views](cm_chap_system-tables.md#c_visibility-of-data).

**Note**  
This view is only available when querying provisioned clusters.

## Table columns
<a name="r_SVV_DISKUSAGE-table-rows"></a>


| Column name  | Data type  | Description  | 
| --- | --- | --- | 
| db\_id  | integer  | Database ID.  | 
| name  | character(72)  | Table name.  | 
| slice  | integer  | Data slice allocated to the table.  | 
| col  | integer  | Zero-based index for the column. Every table you create has three hidden columns appended to it: INSERT\_XID, DELETE\_XID, and ROW\_ID (OID). A table with 3 user-defined columns contains 6 actual columns, and the user-defined columns are internally numbered as 0, 1, and 2. The INSERT\_XID, DELETE\_XID, and ROW\_ID columns are numbered 3, 4, and 5, respectively, in this example.  | 
| tbl  | integer  | Table ID.  | 
| blocknum  | integer  | ID for the data block.  | 
| num\_values  | integer  | Number of values contained on the block.  | 
| minvalue  | bigint  | Minimum value contained on the block.  | 
| maxvalue  | bigint  | Maximum value contained on the block.  | 
| sb\_pos  | integer  | Internal identifier for the position of the super block on disk.  | 
| pinned  | integer  | Whether or not the block is pinned into memory as part of pre-load. 0 = false; 1 = true. Default is false.  | 
| on\_disk  | integer  | Whether or not the block is automatically stored on disk. 0 = false; 1 = true. Default is false.  | 
| modified  | integer  | Whether or not the block has been modified. 0 = false; 1 = true. Default is false.  | 
| hdr\_modified  | integer  | Whether or not the block header has been modified. 0 = false; 1 = true. Default is false.  | 
| unsorted  | integer  | Whether or not a block is unsorted. 0 = false; 1 = true. Default is true.  | 
| tombstone  | integer  | For internal use. | 
| preferred\_diskno  | integer  | Disk number that the block should be on, unless the disk has failed. Once the disk has been fixed, the block will move back to this disk.  | 
| temporary  | integer  | Whether or not the block contains temporary data, such as from a temporary table or intermediate query results. 0 = false; 1 = true. Default is false.  | 
| newblock  | integer  | Indicates whether or not a block is new (true) or was never committed to disk (false). 0 = false; 1 = true.  | 

## Sample queries
<a name="r_SVV_DISKUSAGE-sample-queries"></a>

SVV\_DISKUSAGE contains one row per allocated disk block, so a query that selects all the rows potentially returns a very large number of rows. We recommend using only aggregate queries with SVV\_DISKUSAGE.

Return the highest number of blocks ever allocated to column 6 in the USERS table (the EMAIL column):

```
select db_id, trim(name) as tablename, max(blocknum)
from svv_diskusage
where name='users' and col=6
group by db_id, name;

db_id  | tablename | max
--------+-----------+-----
175857 | users     |   2
(1 row)
```

The following query returns similar results for all of the columns in a large 10-column table called SALESNEW. (The last three rows, for columns 10 through 12, are for the hidden metadata columns.) 

```
select db_id, trim(name) as tablename, col, tbl, max(blocknum)
from svv_diskusage
where name='salesnew'
group by db_id, name, col, tbl
order by db_id, name, col, tbl;

db_id  | tablename  | col |  tbl   | max
--------+------------+-----+--------+-----
175857 | salesnew   |   0 | 187605 | 154
175857 | salesnew   |   1 | 187605 | 154
175857 | salesnew   |   2 | 187605 | 154
175857 | salesnew   |   3 | 187605 | 154
175857 | salesnew   |   4 | 187605 | 154
175857 | salesnew   |   5 | 187605 |  79
175857 | salesnew   |   6 | 187605 |  79
175857 | salesnew   |   7 | 187605 | 302
175857 | salesnew   |   8 | 187605 | 302
175857 | salesnew   |   9 | 187605 | 302
175857 | salesnew   |  10 | 187605 |   3
175857 | salesnew   |  11 | 187605 |   2
175857 | salesnew   |  12 | 187605 | 296
(13 rows)
```