Querying for keywords in photos using DynamoDB and PHP - php

Question

Requirement: I'm storing photos in S3 and want the user to be able to lookup all photos that contain a keyword they type in on a webpage.
My solution: I have created 2 tables:
tblPhotos:
Primary Key=HashKey: PhotoID
Fields:
PhotoID,
S3Location
tblKeywords:
Primary Key=HashKey (HashID) and RangeKey (Keyword)
Fields:
HashID (always set to 1),
Keyword (one big string; the keyword followed by PhotoID)
S3Location
I'm using the following php code to find all records that have my keyword in it:
$table_name = 'tblKeywords';
$keywordresponse = $dynamodb->query(array(
'TableName' => $table_name,
'HashKeyValue' => array(AmazonDynamoDB::TYPE_STRING => '1'),
'RangeKeyCondition' => array(
'ComparisonOperator' => AmazonDynamoDB::CONDITION_BEGINS_WITH,
'AttributeValueList' => array(
array(AmazonDynamoDB::TYPE_STRING => $_GET['sSearch'])
),
)
));
if ($keywordresponse->isOK())
{
foreach ($keywordresponse->body->Items as $item)
{
$aaData[] = array(
'Keyword' => (string) $item->Keyword->{AmazonDynamoDB::TYPE_STRING},
'S3Location' => (string) $item->S3Location->{AmazonDynamoDB::TYPE_STRING}
);
}
echo json_encode(array('keywordstatus' => 1, 'aaData' => $aaData));
}
else
{
echo json_encode(array('keywordstatus' => 0));
}
As you can see I'm passing sSearch as the keyword to filter results on. My question is, do you know a better way to achieve this filtering of records using DynamoDB query? I'm trying to avoid a scan as its very inefficient, although my solution above whilst it works doesn't seem particularly elegant!

Answer 1

If your primary goal is to be able to return all the photos for a given key word I think the following schema would make more sense:
HashKey = Keyword
RangeKey = PhotoID
Additional possible fields: S3Name (if it is not the same as PhotoID)