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| Parameter | Value | Improvement / Remarks |
|---|---|---|
log_buffer | If the version < 9.2.0.7, then the log_buffer=3MB, else the log_buffer=16MB | |
shared_pool_size | 1/4 of the physical memory | The shared pool should not be too small (<250MB) or too large (>2GB) |
log_checkpoint_timeout | 900 | |
open_cursors | 2000 | Make sure you have enough open cursors for the application to execute. |
Processes | 300 | Make sure you have enough open processes for the application to execute. |
db_writer_processes | Should be set according to the number of I/O devices you have for the database | Improves I/O performance in cases of large I/O. Each writer is writing to a different disk (improves loads, for example). |
Table 3 8i 10g parameters
| Parameter | Value | Improvement / Remarks | sort_area_size | (1/8th of the physical memory)/(concurrent users + 10), up to 6MBFor example: If you have 2GB of physical memory and 90 users, then the calculation is: (2GB/8) / 100 ~= 2.5MB | |
|---|---|---|---|---|---|
db_block_buffers | 1/3rd of the physical memory divided by the size of the db_block_size | The given values help to keep the I/O wait of the PMDB queries low. |
Table 4 9i parameters
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Table 5 10g parameters
| Parameter | Value | Improvement / Remarks |
|---|---|---|
sga_target | Automatic memory management. 1/4th of the physical memory. | Replaces the following parameters:
Make sure to initialize them with 0 or the minimum value you need. |
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To improve performance, the DBA on site must modify the Rollback segment settings and the Redo log file settings. The following table describes those settings.
Table 6 Rollback 4 Rollback segment and Redo log file settings
| Setting | Description | Value | ||
|---|---|---|---|---|
| Rollback segments (For 8i) | Minimum tablespace size | 2GB* *4GB recommended in larger installations. | ||
| Rollback segments (For 8i) | Minimum number of segments | 20 | ||
| Rollback segments (For 8i) | Minimum initial segment size | 5MB* *Each Rollback segment should be able to grow to the size of the tablespace. | ||
| Enable AUM (For 9i and above) | Automatic Undo Management See Enabling Automatic Undo Management (AUM) | For 9i and higher | ||
| Temporary tablespace | Minimum temporary tablespace size | 2GB* *The temporary tablespace is most likely to grow according to the PMDB load.
| ||
| Redo log file | Minimum redo log file size | 1GB* *4GB recommended in larger installations
|
Additional Rollback segment and Redo log file information
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The following table shows the default extents sizes.
Table 7 Default 5 Default extents sizes
| Tablespace | Size |
|---|---|
| Large table | 2MB |
| Medium table | 512KB |
| Small table | 80KB |
| Large index | 1MB |
| Medium index | 256KB |
| Small index | 80KB |