Using Cached Updates
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This section provides a basic overview of how cached updates work in an application. If you have not used cached updates before, this process description serves as a guideline for implementing cached updates in your applications.
To use cached updates, the following order of processes must occur in an application:
- 1. Enable cached updates. Enabling cached updates causes a read-only transaction that fetches as much data from the server as is necessary for display purposes and then terminates. Local copies of the data are stored in memory for display and editing. For more information about enabling and disabling cached updates, see Enabling and Disabling Cached Updates.
- 2. Display and edit the local copies of records, permit insertion of new records, and support deletions of existing records. Both the original copy of each record and any edits to it are stored in memory. For more information about displaying and editing when cached updates are enabled, see Applying Cached Updates.
- 3. Fetch additional records as necessary. As a user scrolls through records, additional records are fetched as needed. Each fetch occurs within the context of another short duration, read-only transaction. (An application can optionally fetch all records at once instead of fetching many small batches of records.) For more information about fetching all records, see Fetching Records.
- 4. Continue to display and edit local copies of records until all desired changes are complete.
- 5. Apply the locally cached records to the database or cancel the updates. For each record written to the database, an
OnUpdateRecordevent is triggered. If an error occurs when writing an individual record to the database, an
OnUpdateErrorevent is triggered which enables the application to correct the error, if possible, and continue updating. When updates are complete, all successfully applied updates are cleared from the local cache. For more information about applying updates to the database, see Applying Cached Updates.
If instead of applying updates, an application cancels updates, the locally cached copy of the records and all changes to them are freed without writing the changes to the database. For more information about canceling updates, see Canceling Pending Cached Updates.
- Enabling and Disabling Cached Updates
- Fetching Records
- Applying Cached Updates
- Canceling Pending Cached Updates
- Undeleting Cached Records
- Specifying Visible Records in the Cache
- Checking Update Status