Explanation
Data Synchronization enables developers to automatically sync the contents of a local table with the data from a REST service. APEX invokes the REST service defined in the REST Data Source, downloads all data and synchronizes it to a local table6. Data Synchronization has several benefits, such as:
APEX can create the local table based on the visible columns in the REST Data Source Data Profile. Since the table is physically available in the database schema, developers can add indexes, change physical properties, or even add more columns6.
Data Synchronization helps in providing efficient reporting on large data sets coming from a REST service. Some REST services can return large amounts of result data that include pagination. If a reporting requirement needs larger data sets, this would lead to multiple HTTP requests and poorer response times. Also, no indexes or other database features can be used to speed up reporting queries. In this case, synchronizing the remote data to a local table and having the reports working on local tables can improve performance and user experience6.
Data Synchronization can also collect data from REST services for consumption by PL/SQL packages or other logic. If data from the REST service is replicated to local tables, developers will be able to perform all sorts of processing and also generate different types of reports6.
You do not have to trigger Data Synchronization manually, as you can also schedule it to run periodically using a DBMS_SCHEDULER expression6.