Cache Indexes¶

When enabling the cache for a view, the Cache Module creates a table in the cache’s database that will store the cached data of this view. You can define “Cache indexes” for this view to speed up the retrieval of data from the view’s cache.

The difference between the cache indexes and the indexes defined in the “Indexes” tab is that the latter ones represent the indexes defined in the source. The cache module actually creates the “Cache indexes” in the cache’s database, when they are defined in this tab.

When the cache is enabled for a view and its cache mode is “Full”, the indexes propagated to its derived views and to the ODBC and JDBC clients, are the “Cache indexes” and not the indexes defined in the “Indexes” tab. That is because the queries of the view will always retrieve the data from the cache and not from the source.

To create a cache index, follow these steps:

1. If the view has indexes (see the “Indexes” tab), you can replicate them in the table that will store the view’s cached data, by clicking on Import indexes from view.

   Note that the indexes will not be created until you click Ok to close the dialog.

2. To define more indexes in the cache table, click Create index and follow these steps:

   1. Enter the name of the index.

      Note

      Depending on the database you are using to store the cache, the name of the index may need to be unique across the entire Virtual DataPort database and not just the view you are editing. That is because some databases do not allow defining two indexes with the same name, even if they are defined over different tables.

   2. Select Is unique if the index represents a unicity index.

   3. In the left side of the dialog, there is a list of the fields of the view. Select the ones that belong to the index and click Add >>. To select several fields at once, hold Ctrl or Shift and click on the fields you want to select.

      To change the order of the fields in the index, select the check box of the field you want to move and click on and .

      To remove a field from the index, select its check box in the list of the right side and click << Remove.

   4. Click Ok to create the index.

3. To edit a cache index, select its check box and click Edit selected index.

4. To remove a cache index, select its check box and click Remove selected index.

Cache settings: defining a new “cache index”¶

Cache Refresh Jobs¶

When a view has a cache configured to store data in the cache database’s table, you can load the data manually or create a VDPCache job in Scheduler to do so. This section shows the cache refresh jobs configured for the view and a summary of the most relevant information. You will also have links to the Scheduler Web Administration Tool to get more detailed information about the jobs, manage them, and create new ones.

The table with the VDPCache jobs will load the cache jobs when the collapsible section is expanded the first time. Afterward, to update the table, use the button Reload jobs. The table contains the following information on the cache refresh jobs of the view:

• Job. The name of the VDPCache job. This is a link that will open a new tab for the job details in the Scheduler Web Administration Tool.

• State. The current state of the job. In particular, a job can be found running, not running, waiting, or having been disabled.

• Last execution. This shows the last time the job was executed. It will be blank if it has never been executed.

• Next execution. This shows the next time the job will be executed. It will appear blank if it has been disabled or, according to its time-based scheduling, will not run again.

• Result of the last execution. Shows the completion state of the latest job execution. A job can be completed correctly, end with an error condition detected, end with a warning, stopped by the user, or misfired (that means the scheduled execution didn’t run). If the job ran and didn’t finish correctly, this field will be a link to the execution details section of the Scheduler Web Administration Tool to get more detailed information on the last execution result.

• Cached tuples. Number of tuples/documents that have been extracted in the last execution of the job.

To create a new VDPCache job, click the Add refresh job in Scheduler button. It will open the Scheduler Web Administration Tool in the dialog in a new tab to create a new VDPCache job with some of the fields already filled.