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Formulating queries : Query options and optimizing response times
 

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Query options and optimizing response times

You can refine query results using system query options, which begin with the $ character. Add system query options to the URL to control the amount and order of data in the response. DataDirect Cloud custom query parameters lists additional parameters specific to DataDirect Cloud. In addition, topics in this section describe settings to optimize response times when using the $inlineCount system parameter or when paging through result sets.
The following table lists the OData query string options that DataDirect Cloud supports. For detailed information about the system query options, refer to the OData specification.
Table 2. Supported system query options
Option
Description
Support in DataDirect Cloud
$expand
In addition to retrieving a record or collection, retrieve related records.
At present, supports expanding one level deep.
$filter
An expression or function that must evaluate to true for records that will be included in the response.
Supports all functionality except the isof scalar function.
$inlinecount
Include a count of the number of Entries in the response. The count will be calculated after applying any $filter System Query Options present in the URI. See Improving performance when using inlineCount for more information.
Supports all standard functionality.
$orderby
Determines the values used to order a collection of records.
Supports all standard functionality.
$count
Returns the number of records in a collection, or if the collection has a filter, the number of records that match the filter.
Supports all standard functionality.
$value
Gets the raw value of a property.
Supports all standard functionality.
$top
Identifies a subset of records to return from a collection. To form this subset, select only the first N items of the set, where N is a positive integer. See Paging through results for more information.
Supports all standard functionality.
$skip
Identifies a subset of records to return from a collection. Define the subset by seeking N Entries into the Collection and selecting only the remaining Entries (starting with Entry N+1), where N is a positive integer.
Supports all standard functionality.
* Improving performance when using inlineCount
* Paging through results
* DataDirect Cloud custom query parameters