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Oracle Database Administration: The Essential Refe by Brian Laskey, David C. Kreines

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Dynamically Modifiable Parameters

While most initialization parameters are static—that is, they take their values from the INIT.ORA file when the instance is started—some may be dynamically modified while the instance is up and the database is open. Table 12.2 and Table 12.3 list the tables that may be modified dynamically for Oracle7 and Oracle8, respectively. These tables consist of three columns:

Parameter Name

The name of the parameter, which must be specified in the INIT.ORA file.

Session Modifiable

Indicates whether a parameter may be modified using an ALTER SESSION command.

System Modifiable

Indicates whether a parameter may be modified using an ALTER SYSTEM command. IMMEDIATE indicates that the change takes place immediately, while DEFERRED indicates that the change is deferred until the next session.

Table 12-2. Dynamically Modifiable Initialization Parameters in Oracle7

Parameter Name

Session Modifiable

System Modifiable

B_TREE_BITMAP_PLANS

Yes

No

DB_FILE_MULTIBLOCK_READ_COUNT

Yes

Immediate

HASH_AREA_SIZE

Yes

No

HASH_ JOIN_ENABLED

Yes

No

HASH_MULTIBLOCK_IO_COUNT

Yes

Immediate

LOG_CHECKPOINT_INTERVAL

No

Immediate

LOG_CHECKPOINT_TIMEOUT

No

Immediate

LOG_SMALL_ENTRY_MAX_SIZE

No

Immediate

MAX_DUMP_FILE_SIZE

Yes

No

OPTIMIZER_PERCENT_PARALLEL

Yes

No

OPTIMIZER_SEARCH_LIMIT

Yes

No

PARALLEL_MIN_PERCENT

Yes

No

PARTITION_VIEW_ENABLED

Yes

No

SORT_AREA_RETAINED_SIZE

Yes

Deferred

SORT_AREA_SIZE

Yes

Deferred

SORT_DIRECT_WRITES

Yes

Deferred

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