commit_write可以控制redo的写行为

COMMIT_WRITE

Property         Description

Parameter type         String

Syntax         COMMIT_WRITE = '{IMMEDIATE | BATCH},{WAIT |NOWAIT}'

Default value         If this parameter is not explicitly specified, then database commit behavior defaults to writing commit records to disk before control is returned to the client.

If only IMMEDIATE or BATCH is specified, but not WAIT or NOWAIT, then WAIT mode is assumed.

If only WAIT or NOWAIT is specified, but not IMMEDIATE or BATCH, then IMMEDIATE mode is assumed.

Be aware that the NOWAIT option can cause a failure that occurs after the database receives the commit message, but before the redo log records are written. This can falsely indicate to a transaction that its changes are persistent. Also, it can violate the durability of ACID (Atomicity, Consistency, Isolation, Durability) transactions if the database shuts down unexpectedly.

Modifiable         Yes (at both session-level and system-level). Values supplied for COMMIT_WRITE in an ALTER SYSTEM or ALTER SESSION statement must be separated by a comma.

Range of values         Single-quoted, comma-separated list of either IMMEDIATE or BATCH, and either WAIT or NOWAIT.

Basic         No

Oracle RAC         Each instance may have its own setting

COMMIT_WRITE is an advanced parameter used to control how redo for transaction commits is written to the redo logs. The IMMEDIATE and BATCH options control how redo is batched by Log Writer. The WAIT and NOWAIT options control when the redo for a commit is flushed to the redo logs.

Note:

The COMMIT_WRITE parameter is deprecated. It is retained for backward compatibility only. It is replaced by the COMMIT_LOGGING and COMMIT_WAIT parameters.