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/).
# STV\$1BLOCKLIST
STV\$1BLOCKLIST contains the number of 1 MB disk blocks that are used by each slice, table, or column in a database.
Use aggregate queries with STV\$1BLOCKLIST, as the following examples show, to determine the number of 1 MB disk blocks allocated per database, table, slice, or column. You can also use [STV\$1PARTITIONS](r_STV_PARTITIONS.md) to view summary information about disk utilization.
STV\$1BLOCKLIST 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**
STV\$1BLOCKLIST only records blocks owned by the provisioned cluster or serverless namespace. If the database includes blocks shared from a datashare producer, those blocks aren’t included in STV\$1BLOCKLIST. For more information about datashares, go to [Data sharing in Amazon Redshift](datashare-overview.md).
## Table columns
[\[See the AWS documentation website for more details\]](http://docs.aws.amazon.com/redshift/latest/dg/r_STV_BLOCKLIST.html)
## Sample queries
STV\$1BLOCKLIST 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 STV\$1BLOCKLIST.
The [SVV\$1DISKUSAGE](r_SVV_DISKUSAGE.md) view provides similar information in a more user-friendly format; however, the following example demonstrates one use of the STV\$1BLOCKLIST table.
To determine the number of 1 MB blocks used by each column in the VENUE table, type the following query:
```
select col, count(*)
from stv_blocklist, stv_tbl_perm
where stv_blocklist.tbl = stv_tbl_perm.id
and stv_blocklist.slice = stv_tbl_perm.slice
and stv_tbl_perm.name = 'venue'
group by col
order by col;
```
This query returns the number of 1 MB blocks allocated to each column in the VENUE table, shown by the following sample data:
```
col | count
-----+-------
0 | 4
1 | 4
2 | 4
3 | 4
4 | 4
5 | 4
7 | 4
8 | 4
(8 rows)
```
The following query shows whether or not table data is actually distributed over all slices:
```
select trim(name) as table, stv_blocklist.slice, stv_tbl_perm.rows
from stv_blocklist,stv_tbl_perm
where stv_blocklist.tbl=stv_tbl_perm.id
and stv_tbl_perm.slice=stv_blocklist.slice
and stv_blocklist.id > 10000 and name not like '%#m%'
and name not like 'systable%'
group by name, stv_blocklist.slice, stv_tbl_perm.rows
order by 3 desc;
```
This query produces the following sample output, showing the even data distribution for the table with the most rows:
```
table | slice | rows
----------+-------+-------
listing | 13 | 10527
listing | 14 | 10526
listing | 8 | 10526
listing | 9 | 10526
listing | 7 | 10525
listing | 4 | 10525
listing | 17 | 10525
listing | 11 | 10525
listing | 5 | 10525
listing | 18 | 10525
listing | 12 | 10525
listing | 3 | 10525
listing | 10 | 10525
listing | 2 | 10524
listing | 15 | 10524
listing | 16 | 10524
listing | 6 | 10524
listing | 19 | 10524
listing | 1 | 10523
listing | 0 | 10521
...
(180 rows)
```
The following query determines whether any tombstoned blocks were committed to disk:
```
select slice, col, tbl, blocknum, newblock
from stv_blocklist
where tombstone > 0;
slice | col | tbl | blocknum | newblock
-------+-----+--------+----------+----------
4 | 0 | 101285 | 0 | 1
4 | 2 | 101285 | 0 | 1
4 | 4 | 101285 | 1 | 1
5 | 2 | 101285 | 0 | 1
5 | 0 | 101285 | 0 | 1
5 | 1 | 101285 | 0 | 1
5 | 4 | 101285 | 1 | 1
...
(24 rows)
```