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Oracle-Specific Database Requirements


The following requirements apply to Oracle RDBMS usage:

Table 12.  Recommended Variable Settings for Oracle Databases
Parameter
Recommended Setting
Notes
Always_anti_join
HASH
Not available in Oracle 9i or later.
Cursor_space_for_time
TRUE
Use only if you do not have many concurrent connections.
Db_block_lru_latches
Set to number of CPUs
 
Db_block_size
32k
 
Db_file_direct_io_count
64
Not available in Oracle 9i or later.
Db_file_multiblock_read_count
STMAXIO / DB_BLOCK_SIZE
 
Db_file_multiblock_read_count
32
 
Default Pctincrease
0
 
Hash_area_size
20 MB
 
Hash_multiblock_io_count
0.5 * ( db_file_multiblock_Read_count)
Make sure that you are not using MTS.
Initial Extent
20 MB
 
Log_buffer
2 MB
 
Next Extent
20 MB
 
Optimizer_index_caching
Unset
Unset this to avoid nested loops index joins (as favored by the optimizer).
Optimizer_index_cost_adjust
Set to default
See NOTE following these parameters.
Optimizer_max_permutations
default of 80,000
May be applicable to other schemas in the database. This means longer parsing times for the access paths, but once these are parsed, they should remain in the shared_pool, provided they do not get aged out. See notes for Cursor_space_for_time.
Optimizer_mode
ALL_ROWS
Cost-based for Refresh ETL
Rule- based for Full ETL.
Query_rewrite_integrity
USE_STALE
 
Rollback_segments
For a development instance, no more than 2
Each rollback_segment sized as follows:
  • Initially 10 MB
  • Next 10 MB
  • Minextents 10 MB
  • Maxextents unlimited
  • Optimal 1000 MB
Shared_pool_size
34 MB
 
Sort_area_retained_size
10 MB
 
Sort_area_size
10 MB
 
Sort_multiblock_read_count
4
Not available in Oracle 9i or later.
Star_transformation_enabled
TRUE
 
Tablespace
At least 50% of Siebel transactional database size
Make sure the temporary tablespace has adequate space.
Number of log file groups
4
 
Size of each Log file
10MB
 

Notes on OPTIMIZER_MODE Settings for Oracle

Take note of these OPTIMIZER_MODE settings:

Additional Suggestions for Optimizing Oracle Performance


 Siebel Data Warehouse Installation and Administration Guide
 Published: 09 September 2004