07.Delete DB items

import boto3
 
REGION = "us-west-1"
TABLE_NAME = "S3-object-size-history"
 
def empty_dynamodb_table(table_name: str, region: str) -> int:
    dynamodb = boto3.resource("dynamodb", region_name=region)
    table = dynamodb.Table(table_name)
 
    # Get primary key attributes (PK / SK)
    key_names = [k["AttributeName"] for k in table.key_schema]
 
    # Only scan key attributes (cheaper)
    expr_attr_names = {f"#{k}": k for k in key_names}
    proj_expr = ", ".join(expr_attr_names.keys())
 
    deleted = 0
    scan_kwargs = {
        "ProjectionExpression": proj_expr,
        "ExpressionAttributeNames": expr_attr_names,
    }
 
    while True:
        resp = table.scan(**scan_kwargs)
        items = resp.get("Items", [])
 
        with table.batch_writer() as batch:
            for it in items:
                key = {k: it[k] for k in key_names}
                batch.delete_item(Key=key)
                deleted += 1
 
        last_key = resp.get("LastEvaluatedKey")
        if not last_key:
            break
        scan_kwargs["ExclusiveStartKey"] = last_key
 
    return deleted
 
if __name__ == "__main__":
    n = empty_dynamodb_table(TABLE_NAME, REGION)
    print(f"Deleted {n} items from {TABLE_NAME}")