Summary information |
|
|---|---|
Default value |
0 |
Range of values |
0–65535 |
Status |
Dynamic |
Display level |
Comprehensive |
Required role |
System administrator |
Configuration group |
Cache Manager |
number of index trips specifies the number of times an aged index page traverses the most recently used/least recently used (MRU/LRU) chain before it is considered for swapping out. As you increase the value of number of index trips, index pages stay in cache for longer periods of time.
A data cache is implemented as an MRU/LRU chain. As the user threads access data and index pages, these pages are placed on the MRU end of the cache’s MRU/LRU chain. In some high transaction environments (and in some benchmarks), you may want to keep index pages in cache, since they will probably be needed again soon. Setting number of index trips higher keeps index pages in cache longer; setting it lower allows index pages to be swapped out of cache sooner.
You need not set the number of index trips for relaxed LRU pages. See Chapter 4, “Configuring Data Caches,” in the System Administration Guide: Volume 2.
If the cache used by an index is relatively small (especially
if it shares space with other objects) and you have a high transaction
volume, do not set number of index trips too
high. The cache can flood with pages that do not age out, and this
may lead to the timing out of processes that are waiting for cache space.
Before changing the value of number of index trips to
a number other than 0, make sure the application has sufficient
cache to store all index, OAM, and data pages. Consult Sybase Technical
Support before changing the value of number of index trips.
