79989

To predict the percentage of reads saved for difTerent databa.se cache sizes:

1.    In EM Express, from the Configu ratfon menu, select Memory.

The Memory Management page appears. In the Memory Settings section, the Management Modę value is Manuał in the SGA Memory subsection.This indicates that Manuał Shared Memory Management is enabled for the database.

2.    Use the Buffer Cache Advisor graph (which appears to the right of the Memory Settings section) to predict the percentage of reads saved for potential database cache sizes.

In the Buffer Cache Advisor graph:

■Potential values for the DB_CACHE_SIZE initialization parameter (in MB) are represented on the horizontal axis of the graph. The current setting of the DB_ CACHE_SI ZE initialization parameter is indicated by a blue dot.

■The corrcsponding values of reads saved are represented on the vcrtical axis of the graph. The plotted values are expressed as a percentage relative to the currcnt setting of the DB_CACHE_SIZE initialization parameter.

Negative values represent the percentage of an increase in reads (when the mcmory allottcd to Oracle is smallcr than the current setting). whilc positivc valucs represent the percentage of dccrcasc in reads (when the mcmory alloted to Oracle is larger than the current setting.

An orange linę on the graph plots different values that can be specified for the DB_ CACHE_SIZE initialization parameter. Click any dot on the orange linę to see a prediction of the percentage of reads saved for the DB_CACHE_SIZE value represented by that dot.

In this figurę, the Buffer Cache Advisor graph indicates that inereasing the current value of the DB_CACHE_SIZE initialization parameter will not increase the percentage of reads savcd.

3.    To change the value of the DB_CACHE_SIZE initialization parameter:

a.    Click Configure Memory on the Mcmory Management page.

The Initialization Parameter page appears.

b.    Select the DB_CACHE_SIZE initialization parameter and click Set.

The Set Initialization Parameter page appears.