Disabling Explicit Garbage Collection

2-10 Oracle Fusion Middleware Performance and Tuning Guide

2.6.1.2 Initialization Parameters for Oracle 11g

The following table provides information on some important performance-related database initialization parameters for Oracle 11g database. PL_SQL_CODE_TYPE PLSQL_CODE_TYPE specifies the compilation mode for PLSQL library units. INTERPRETED: PLSQL library units are compiled to PLSQL bytecode format. Such modules are executed by the PLSQL interpreter engine. NATIVE: PLSQL library units are compiled to native machine code. Such modules are executed natively without incurring any interpreter impacts. PROCESSES Sets the maximum number of operating system processes that can be connected to Oracle concurrently. The value of this parameter must account for Oracle background processes. SESSIONS parameter is deduced from this value. PGA_AGGREGATE_TARGET Specifies the target aggregate PGA memory available to all server processes attached to the instance. SGA_MAX_SIZE This parameter is the maximum size of the SGA for a running instance. Set this parameter to the amount of memory that you want dedicated for the SGA, which includes the following memory pools: ■ Database buffer cache ■ Shared pool ■ Large pool ■ Java pool Ensure that you regularly monitor the buffer cache hit ratio and size the SGA so that the buffer cache has an adequate number of frames for the workload. The buffer cache hit ratio may be calculated from data in the view VSYSSTAT. Also the view VDB_CACHE_ADVICE provides data that can be used to tune the buffer cache. SGA_TARGET Setting this parameter to a nonzero value enables Automatic Shared Memory Management. Consider using automatic memory management, both to simplify configuration and to improve performance. TRACE_ENABLED TRACE_ENABLED controls tracing of the execution history, or code path, of Oracle. Oracle Support Services uses this information for debugging. Although the performance impacts incurred from processing is not excessive, you may improve performance by setting TRACE_ENABLED to FALSE. Table 2–3 Important inti.ora Oracle 11g Database Tuning Parameters Database Parameter Description AUDIT_TRAIL AUDIT_TRAIL enables or disables database auditing. MEMORY_MAX_ TARGET MEMORY_MAX_TARGET specifies the maximum value to which a DBA can set the MEMORY_TARGET initialization parameter. MEMORY_TARGET MEMORY_TARGET specifies the Oracle system-wide usable memory. The database tunes memory to the MEMORY_TARGET value, reducing or enlarging the SGA and PGA as needed. PGA_AGGREGATE_ TARGET Specifies the target aggregate PGA memory available to all server processes attached to the instance. In Oracle 11g, set MEMORY_TARGET instead of setting SGA and the PGA separately. SGA_MAX_SIZE Consider setting MEMORY_TARGET instead of setting SGA and the PGA separately. SGA_TARGET Consider setting MEMORY_TARGET instead of setting SGA and the PGA separately. Table 2–2 Cont. Important init.ora Oracle 10g Database Tuning Parameters Database Parameter Description