# Using Aggregate to perform summary calculations on selected fields
<a name="transforms-aggregate-fields"></a>

**To use the Aggregate transform**

1.  Add the Aggregate node to the job diagram. 

1.  On the **Node properties** tab, choose fields to group together by selecting the drop-down field (optional). You can select more than one field at a time or search for a field name by typing in the search bar. 

    When fields are selected, the name and datatype are shown. To remove a field, choose 'X' on the field.   
![\[The screenshot shows the Transform tab for the Aggregate node.\]](http://docs.aws.amazon.com/glue/latest/dg/images/Aggregate-transform-tab.png)

1.  Choose **Aggregate another column**. It is required to select at least one field.   
![\[The screenshot shows the fields when choosing Aggregate another column.\]](http://docs.aws.amazon.com/glue/latest/dg/images/Aggregate-fieldtoaggregate.png)

1.  Choose a field in the **Field to aggregate** drop-down. 

1.  Choose the aggregation function to apply to the chosen field: 
   +  avg - calculates the average 
   +  countDistinct - calculates the number of unique non-null values 
   +  count - calculates the number of non-null values 
   +  first - returns the first value that satisfies the 'group by' criteria 
   +  last - returns the last value that satisfies the 'group by' criteria 
   +  kurtosis - calculates the the sharpness of the peak of a frequency-distribution curve 
   +  max - returns the highest value that satisfies the 'group by' criteria 
   +  min - returns the lowest value that satisfies the 'group by' criteria 
   +  skewness - measure of the asymmetry of the probability distribution of a normal distribution 
   +  stddev\$1pop - calculates the population standard deviation and returns the square root of the population variance 
   +  sum - the sum of all values in the group 
   +  sumDistinct - the sum of distinct values in the group 
   +  var\$1samp - the sample variance of the group (ignores nulls) 
   +  var\$1pop - the population variance of the group (ignores nulls)