direct path write
During Direct Path operations, the data is asynchronously written to the database files. At some stage the session needs to make sure that all outstanding asynchronous I/O have been completed to disk.
Detailed Description​
This wait is seen when Oracle is waiting on confirmation that all async writes have been completed.
You will see direct path write waits when:
- When parallel execution servers are scanning for data including Parallel Create Table As Select
- Direct-path INSERTs.
- Some LOB operations.
Your process writes data from disk directly from your process's private memory - the Program Global Area (PGA) rather than the shared memory normally associated with database writes. Asynchronous I/O will be used if possible.
How to reduce this wait​
As direct writes should happen at near disk speed, check the disk subsystem to ensure it is not overloaded.
Additional Links​
Oracle Performance Tuning Guide - direct path write and direct path write
Tuning script from oracle-base.com
Oracle Reference - PGA_AGGREGATE_TARGET
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