Presto Administration : Presto Server Configuration : BigMemory for Caching, Connections and Presto Analytics : Configuring Mashable/Mashup Response Caching : Controlling Response Cache Entries Dynamically
Controlling Response Cache Entries Dynamically
You can use HTTP headers in requests or responses to provide individual control of cache entries that override all other cache configuration. This uses the HTTP Cache-Control header.
You can add HTTP headers to requests to run mashables or mashups using Presto Connect or the Presto REST API. To set caching headers in responses, wrap requests to run mashables in a mashup and use EMML statements in the mashup to add the HTTP headers to the response. See Adding HTTP Headers to the Mashup Result for instructions.
Where you add this header and the specific value determines the effect:
*To ensure that the response is no older than a specific number of milliseconds, set one of the following HTTP headers in a request to invoke a mashable or mashup:
*CACHE-CONTROL: "max-age=number-of-seconds"
*max-age=number-of-seconds
*To set the maximum age of a new cache entry created for a specific response, set one of these HTTP headers in the mashable or mashup response:
*CACHE-CONTROL: "max-age=number-of-seconds"
*max-age=number-of-seconds
*To force the Presto Server to discard the current cache entry and invoke a mashable or mashup, set one of these HTTP headers in the mashable or mashup request:
*CACHE-CONTROL: no-cache
*no-cache
*To ensure the current response is not cached, set one of these HTTP headers in the mashable or mashup response:
*CACHE-CONTROL: no-cache
*no-cache
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