Using Caching in the Database Explorer

The Database Explorer has two options for caching the data in the displays.

• the History Cache. This caches the displays to memory
• the Disk Cache. This caches the displays to disk.

Caching will save a lot of time in AQT if you are moving around the Database Explorer. It saves AQT from continually re-fetching information on objects from the database. This can give a significant performance improvement if you are dealing with large databases, plus reduces the load on the network plus database.

The Disk Cache was introduced in AQT v11 and supercedes the History Cache. However the History Cache has been retained as some users may prefer it over the Disk Cache.

The pros and cons of these two caches are as follows:

• both will cache both the list-of-schemas (which appears in the Object Tree) plus the list-of-objects (which appear in Object List)
• the History Cache holds the data in memory so will result in more memory being used, particularly if you have a large number of objects in your database.
• the Disk Cache holds data to disk, so the data is retained between AQT sessions. This will allow a faster startup of AQT if it takes a long time for AQT to fetch the list of your database objects.
• by contrast, the History Cache will not retain any data between sessions. Some users prefer this as it allows a "clean" startup of AQT every time.

The options for specifying caching are given in Options > Database Explorer.

History Cache

History Caching is enabled by default.

When AQT is displaying information from the cache, you will see the following message in the status-bar:

x objects loaded from History buffer. Hit F5 if you need to refresh the data

Hitting F5 (Refresh) will re-fetch the data from the database. You might need to do this if you have created or dropped some objects.

The History icon (above the Object Tree) gives you quick access to your recently displayed objects.

Disk Cache

To use this form of caching, go to Options > Database Explorer. Click on Use Disk Cace for Schemas and/or Use Disk Cache for Objects.

When either of these options are used, the History Cache will be disabled.

When AQT has fetched the data from the disk cache, you will get the following messages in the bar at the bottom of the displays.

• (for the Object Tree) xx schemas displayed from cache. Hit F6 to refresh
• (for the Object List) xx objects displayed from cache. Hit F5 to refresh

You may wish to refresh the displays if more schemas or objects have been created. You can do this with F5/F6 or hitting the Refresh buttons above the displays.

Noe: when F6 is hit to refresh the schemas, all the schemas in the Object Tree are refreshed.