Mapping and visualization > Navigating and interacting with maps > Navigating maps and layout pages
Working with the map cache |
|
|
Release 9.3
Last modified September 11, 2008 |
Print all topics in : "Navigating maps and layout pages" |
About working with the map cache
If you're working with data stored in a geodatabase or from an ArcIMS feature service, building the map cache can often speed up common ArcMap tasks. The map cache allows you to temporarily store the features in the current map display in ArcMap to your local machine's memory. Because retrieving the features from local memory is a fast operation, using the map cache will often result in performance improvements.
The map cache only stores features in geodatabases and ArcIMS feature services, so no data from rasters, coverages, shapefiles, or other types of services is cached. The map cache is most useful when you will be working within a specific area of a map.
For example, if you are working with data in an ArcSDE geodatabase that serves features over a network, features in the current extent must be retrieved from the source database each time your display is updated. Building a map cache, however, can reduce the load on your network and the geodatabase since ArcMap accesses this information from your computer's random access memory (RAM). Since features are cached on the client, it reduces the number of queries the client needs to execute on the server.
Some of the activities that can often benefit from a map cache include drawing large or complex datasets, labeling, editing, selecting features, retrieving the same features for multiple layers on a map, and drawing features using a definition query. Labeling, for example, can be a slow and costly process, requiring multiple round-trips to the data source as the label engine attempts to place the maximum number of labels on the map.
Learn more about labels
Using the map cache tools
ArcMap has tools to help you build and work with the map cache. These tools are found on the Map Cache toolbar. You can create a map cache by clicking the Build Map Cache button 
. You can also use the automatic cache (auto-cache) function to automatically update the map cache whenever you move outside the currently cached extent.
The auto-cache can be useful if you are going to be working in a series of different geographic areas and you don't want to rebuild the cache for each area. It is also convenient when you don't know the exact boundaries of the area you want to cache.
Since auto-cachemay hinder performance, you should set an auto-cache minimum scale. A map cache will be created automatically unless the map is zoomed out beyond the minimum scale. For example, suppose you set 1:50,000,000 as the minimum scale. When the map is zoomed in to 1:14,500,000, the map cache will be created automatically, but when the map is zoomed out to 1:75,000,000, the map cache will not be rebuilt.
Maximizing the map cache's performance advantages
For geodatabase data, the advantages of the map cache are most pronounced when the data source is an ArcSDE geodatabase. In a multiuser environment, consistent use of the map cache in ArcMap can significantly improve the overall performance of the system by reducing the number of queries to the geodatabase, the number of features retrieved from the geodatabase, and the overall network traffic. Care must be taken, though, when using map caches to edit in multiuser, nonversioned edit sessions.
In addition, there may be a minor performance gain with a map cache for file or personal geodatabases such as when editing features with large numbers of vertices or accessing the data over a network.
When working with ArcIMS feature services, the map cache can also help reduce traffic to the server. ArcIMS image and ArcMap Server services are not supported by the map cache.
Whether you are using geodatabase or feature service data, the map cache is most useful when you will be working within a specific area of a map. Work that requires frequent panning and zooming across a large area will not usually benefit from a map cache.
Learn more about the map cache and nonversioned editing
How to work with the map cache
Adding the Map Cache toolbar
Click View, point to Toolbars, and click Map Cache.
The Map Cache toolbar appears.
Building a map cache
- Pan or zoom to the area on the map where you want to work.
- Click the Build Map Cache button on the Map Cache toolbar.
The features in the current extent are held in memory locally.
| Tips |
|
on the Map Cache toolbar.
on the Map Cache toolbar.Setting the auto-cache minimum scale
- Zoom out just beyond the scale at which you'll be working.
- Click the Set Auto-Cache Scale button
on the Map Cache toolbar.
| Tips |
|
Setting auto-cache options
- Click View and click Data Frame Properties.
- Click the Map Cache tab.
- Check Automatically create map cache to use the auto-cache.
- Check the Set minimum scale for auto-cache box.
- Type a minimum scale in the box or click the Use Current Scale button to set the current scale as the minimum scale.
- Click OK.
Clearing the auto-cache minimum scale
Click the Clear Auto-Cache Scale button 
on the Map Cache toolbar.
Seeing the extent of the cached area
Click the Show Map Cache button on the Map Cache toolbar.
The currently cached area will flash on the map.
- If the Show Map Cache button is green
, you are using the map cache. Green indicates that you are completely within the cached extent and are using cached data.
- If the Show Map Cache button is red
, part of your current display extent is outside the cached area. You are no longer using cached data.
- If the button is unavailable
, you are completely outside the cached area. You are no longer using cached data.
In the example, the area outside the rectangle is not within the current cache extent, so the Show Map Cache button would be red.
-Optionally, if you plan on working at this extent, click the Build Map Cache button to build a new cache or click the Auto-Cache button to use the auto-cache.
| Tips |
|