Configuring Reusable Expressions for a Search Domain in Amazon CloudSearch

When you define an expression in a domain's configuration, you can reference the expression in any search request. Adding an expression to the domain configuration reduces the overhead of specifying it in every request, and helps maximize response times and minimize costs.

When you add an expression to your domain configuration, it takes some time for the change to be processed and the new expression to become active. To quickly test changes to an expression, you can define and use the expression directly in a search request, as described in query time expressions. After you have finished testing and tuning an expression, you should add it to your domain configuration.

Configuring Expressions Using the Amazon CloudSearch Console

To configure an expression

1. Open the Amazon CloudSearch console at https://console.aws.amazon.com/cloudsearch/home.

2. From the left navigation pane, choose Domains.

3. Choose the name of the domain to open its configuration.

4. Go to the Advanced search options tab.

5. In the Expressions pane, choose Add expression.

6. Enter a name for the new expression.

7. For Value, enter the numerical expression that you want to evaluate at search time. You can select Insert to add special values and mathematical and trigonometric functions.

8. Choose Save.

Configuring Amazon CloudSearch Expressions Using the AWS CLI

You use the aws cloudsearch define-expression command to define computed expressions for a domain.

To configure an expression

• Run the aws cloudsearch define-expression command to define a new expression. You specify a name for the expression with the --name option, and the numeric expression that you want to evaluate with the --expression option. For example, the following request creates an expression called popularhits that takes into account a document's popularity and relevance _score.

  aws cloudsearch define-expression --domain-name movies --name popularhits --expression '((0.3*popularity)/10.0)+(0.7* _score)'
  
  {
      "Expression": {
          "Status": {
              "PendingDeletion": false, 
              "State": "Processing", 
              "CreationDate": "2014-05-01T01:15:18Z", 
              "UpdateVersion": 52, 
              "UpdateDate": "2014-05-01T01:15:18Z"
          }, 
          "Options": {
              "ExpressionName": "popularhits", 
              "ExpressionValue": "((0.3*popularity)/10.0)+(0.7* _score)"
          }
      }
  }

Configuring Expressions Using the Amazon CloudSearch Configuration API

The AWS SDKs (except the Android and iOS SDKs) support all of the Amazon CloudSearch actions defined in the Amazon CloudSearch Configuration API, including DefineExpression. For more information about installing and using the AWS SDKs, see AWS Software Development Kits.