Aggregate functions - Amazon Simple Storage Service
SUM example
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Aggregate functions

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

To aggregate the total object sizes of a folder in an S3 Inventory report, 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.

  • 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