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/).
# VAR\_SAMP and VAR\_POP functions
The VAR\_SAMP and VAR\_POP functions return the sample and population variance of a set of numeric values (integer, decimal, or floating-point). The result of the VAR\_SAMP function is equivalent to the squared sample standard deviation of the same set of values.
VAR\_SAMP and VARIANCE are synonyms for the same function.
## Syntax
```
VAR_SAMP | VARIANCE ( [ DISTINCT | ALL ] expression)
VAR_POP ( [ DISTINCT | ALL ] expression)
```
The expression must have an integer, decimal, or floating-point data type. Regardless of the data type of the expression, the return type of this function is a double precision number.
**Note**
The results of these functions might vary across data warehouse clusters, depending on the configuration of the cluster in each case.
## Usage notes
When the sample variance (VARIANCE or VAR\_SAMP) is calculated for an expression that consists of a single value, the result of the function is NULL not 0.
## Examples
The following query returns the rounded sample and population variance of the NUMTICKETS column in the LISTING table.
```
select avg(numtickets),
round(var_samp(numtickets)) varsamp,
round(var_pop(numtickets)) varpop
from listing;
avg | varsamp | varpop
-----+---------+--------
10 | 54 | 54
(1 row)
```
The following query runs the same calculations but casts the results to decimal values.
```
select avg(numtickets),
cast(var_samp(numtickets) as dec(10,4)) varsamp,
cast(var_pop(numtickets) as dec(10,4)) varpop
from listing;
avg | varsamp | varpop
-----+---------+---------
10 | 53.6291 | 53.6288
(1 row)
```