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Refresh strategies for data pages

Stale data and data refresh

Out-of-date data — also referred to as stale data — can lead to bad decisions, costly errors, and inefficient processes. Keeping the contents of a data page current is critical for ensuring accurate, desirable case outcomes. The first time users access a data page, Pega Platform™ populates the page with up-to-date information. Subsequent users access the same cached data, even if the source data changes. To keep data pages current with changes in sourced data, configure a refresh strategy to identify and limit stale data.

Note: The use of a refresh strategy is optional but strongly recommended for data pages to prevent users from viewing and acting upon stale data.

Refresh strategies

The refresh strategy for a data page defines one or more conditions for testing whether the contents of a data page are considered stale and need to be reloaded. When a user accesses a data page, Pega Platform checks the refresh conditions configured for the data page. If a page meets at least one of the conditions, Pega Platform reloads the page contents from the specified data source.

Note: Designing a data page refresh strategy requires balancing processing effort against the chance that a data page contains stale data, especially for a page with the scope set to Thread. Always consult with project stakeholders to determine acceptable limits on performance impacts and stale data before configuring a refresh strategy.

In a data page record, the Load management tab provides developers with three options for configuring a refresh strategy for a read-only data page. 

Reload once per interaction

The Reload once per interaction option updates the contents of the data page each time a user accesses the page in memory. This option is available only for pages with the scope set to Thread or Requestor and cannot be combined with any other refresh option.

For example, travel reservation populates a data page with seating information for the flight selected by a customer. Select Reload once per interaction to update the data page every time the customer accesses the page, to ensure that the seating information is as current as possible.

Do not reload when

The Do not reload when option uses a when condition to test whether the data page is considered stale. If the condition returns a result of true, the contents of the data page are considered current and Pega Platform does not attempt to update the data page.

For example, a data page contains pricing and volume information for a specified security. After the trading day ends, the price and volume remain constant until trading resumes on the next business day. To prevent unneeded refreshing of the data page, configure a condition to prevent Pega Platform from reloading the page after the trading day ends and before the next trading day begins.

Reload if older than

The Reload if older than option uses a fixed interval of time to determine whether a data page is stale. After the interval ends, the data page contents are considered stale, and the next attempt to access the data page causes Pega Platform to update the data page. So, if a data page with a Reload if older than interval of 10 minutes is first accessed at 1200 (12:00 PM), the page is considered stale at 1210 (12:10 PM). Pega Platform then updates the contents of the page when a user accesses the stale page, which may not occur until 1300 (1:00 PM). 

For example, an employee onboarding case allows a manager to assign a seating location to a new employee. An inventory of seating locations with the status of each location is stored in a database table and filtered to populate a data page with available seating locations at the branch office specified in the onboarding case. The data page is parameterized to maintain an instance for each branch office. Stakeholders are confident that refreshing the page every minute is enough to avoid duplicate selections by managers.

Tip: Consider the frequency of data changes to design a refresh strategy that minimizes the processing burden due to reloading data pages. A data page containing pricing data, such as an ecommerce online shopping company, must be refreshed every second of the day to reflect a change in price. A data page listing automobile makes and models may only need to be refreshed every 30-60 days.

Pega Platform never refreshes a data page more than one time per interaction, regardless of how the data page refresh options are configured.

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