# Aggregate functions
<a name="s3-select-sql-reference-aggregate"></a>

**Important**  
Amazon S3 Select is no longer available to new customers. Existing customers of Amazon S3 Select can continue to use the feature as usual. [Learn more](https://aws.amazon.com/blogs/storage/how-to-optimize-querying-your-data-in-amazon-s3/) 

Amazon S3 Select supports the following aggregate functions.


| Function | Argument type | Return type | 
| --- | --- | --- | 
| `AVG({{expression}})` | `INT`, `FLOAT`, `DECIMAL` | `DECIMAL` for an `INT` argument, `FLOAT` for a floating-point argument; otherwise the same as the argument data type. | 
| `COUNT` |  `-`  | `INT` | 
| `MAX({{expression}})` | `INT`, `DECIMAL` | Same as the argument type. | 
| `MIN({{expression}})` | `INT`, `DECIMAL` | Same as the argument type. | 
| `SUM({{expression}})` | `INT`, `FLOAT`, `DOUBLE`, `DECIMAL` | `INT` for an `INT` argument, `FLOAT` for a floating-point argument; otherwise, the same as the argument data type. | 

## SUM example
<a name="s3-select-sql-reference-aggregate-case-examples"></a>

To aggregate the total object sizes of a folder in an [S3 Inventory report](https://docs.aws.amazon.com/AmazonS3/latest/userguide/storage-inventory.html), use a `SUM` expression.

The following S3 Inventory report is a CSV file that's compressed with GZIP. There are three columns.
+ The first column is the name of the S3 bucket ({{`DOC-EXAMPLE-BUCKET`}}) that the S3 Inventory report is for.
+ The second column is the object key name that uniquely identifies the object in the bucket.

  The `{{example-folder/}}` value in the first row is for the folder `{{example-folder}}`. In Amazon S3, when you create a folder in your bucket, S3 creates a 0-byte object with a key that's set to the folder name that you provided.

  The `{{example-folder/object1}}` value in the second row is for the object `{{object1}}` in the folder `{{example-folder}}`.

  The `{{example-folder/object2}}` value in the third row is for the object `{{object2}}` in the folder `{{example-folder}}`.

  For more information about S3 folders, see [Organizing objects in the Amazon S3 console by using folders](using-folders.md).
+ The third column is the object size in bytes.

```
"{{DOC-EXAMPLE-BUCKET}}","{{example-folder/}}","0"
"{{DOC-EXAMPLE-BUCKET}}","{{example-folder/object1}}","2011267"
"{{DOC-EXAMPLE-BUCKET}}","{{example-folder/object2}}","1570024"
```

To use a `SUM` expression to calculate the total size of the folder `{{example-folder}}`, run the SQL query with Amazon S3 Select.

```
SELECT SUM(CAST(_3 as INT)) FROM s3object s WHERE _2 LIKE '{{example-folder/}}%' AND _2 != '{{example-folder/}}';
```

Query Result: 

```
3581291
```