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WEBSPHERE PORTAL V6.1 TUNING GUIDE
D A T A S T O R E
The datastore caches contain data read from the portal database. It is not the goal of these
caches to be a complete image of the DB content, but to have frequently-accessed but raw
information available for all other portal components to use.
com.ibm.wps.datastore.services.Identification.OidAndUniqueName.cache
Default size: 5000, default lifetime: infinite, usage pattern: regular.
This cache stores unique names. It is used quite frequently during page rendering and
especially administration of unique names. Page and portlet unique names make up the
biggest part of the cache content. The cache should be large enough to hold entries for
the most frequently used pages and portlets having a unique name associated with
them. Note that not all resources have a unique name associated with them. To
eliminate database lookups the cache size could correspond to the database table
UNIQUE_NAME multiplied by two, to allow for mapping in two directions. Creating a
cache entry involves reading one entry from the portal database. An entry object into the
cache is fairly small.
com.ibm.wps.datastore.PortalIdCache.vpPerLpid.cache
Default size: 1000, default lifetime: infinite, usage pattern: regular.
This cache maps long Virtual Portal object IDs to the corresponding portal internal short
ID. It scales with the number of virtual portals in the system, plus one additional entry. It
is used heavily only if more than one virtual portal exists in the system. Data is read from
the cache during every rendering request then. For optimal caching the size should be
set to the number of Virtual Portals defined in the system. Creating a cache entry
involves one single-row database lookup. An entry object into the cache is fairly small.
com.ibm.wps.datastore.PortalIdCache.explicitLpidPerVP
Default size: 100, default lifetime: infinite, usage pattern: regular.
This cache maps the short object ID for a virtual portal to the corresponding long ID. In
comparison to cache com.ibm.wps.datastore.PortalIdCache.vpPerLpid.cache it stores
the reverse mappings. Hence all other descriptions given above also apply here.
com.ibm.wps.datastore.pageinstance.OIDCache
Default size: 3000, default lifetime: infinite, usage pattern: regular.
This cache stores information on portal pages for fast retrieval during login or page
navigation. It scales with the number of page instances in the system. It is one of the
most frequently used caches and should be large enough to hold all pages that are
frequently accessed by users. Pages are loaded and put into the cache by direct
navigation, creating a link to another page or by working with the page during portal
administration (always including all higher derivation levels). Creating a cache entry
includes one single-row database lookup. An entry to the cache is medium sized. To