Tuesday, October 11, 2022

Joel Kallman Day 2022: APEX Caching #joelkallmanday

 I'm writing a short blog post today as part of the Joel Kallman Day.

"Server-Side Caching" is probably an under-utilized feature of Oracle APEX. It's very easy to use, and can have an amazing impact on the performance of your APEX application, and make it (even) more scalable.


What is APEX Server Caching?

Here's how the help text explains it:

"Select how the Oracle APEX engine can cache HTML text on the server side. If caching can be used, it emits the cached result instead of computing it again. This cuts down on expensive computation time on the server. This feature is unrelated to the browser's caching capabilities."

In other words, if you have a report, or a chart, or some content generated dynamically by PL/SQL, the APEX engine can store the final result (the HTML text) of that content and just display that instead of having to re-run a query or execute your code.

What can be cached?

You can cache whole Pages, or individual Regions.


Cache settings

You can choose how to cache (by session, by user, or for everyone) and how long to cache. You can also select one or more items; if the value of these items change, the cache will automatically be invalidated and refreshed on the next view. You can also combine this with a more complex Condition.

APEX API packages related to caching

The following packages are related to caching:

APEX Dictionary View

The view APEX_APPLICATION_CACHING gives you information about caching, useful for debugging and monitoring.

Bonus: Tip

On pages where you use caching, create a button to clear the cache immediately (and perhaps conditionally display the button for admins/developers). This will make your life as a developer easier. Remember that any changes you as a developer make to reports, etc. will no longer be immediately visible if they are cached!

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