Direct path read (%)


The session is waiting for a direct read to complete. A direct read is a physical I/O from a data file that bypasses the buffer cache and reads the data block directly into process-private memory.

If asynchronous I/O is supported (and in use), then Oracle can submit I/O requests and continue processing. Oracle can then pick up the results of the I/O request later and wait on "direct path read" until the required I/O completes.

If asynchronous I/O is not being used, then the I/O requests block until completed but these do not show as waits at the time the I/O is issued. The session returns later to pick up the completed I/O data but can then show a wait on "direct path read" even though this wait will return immediately.

Hence this wait event is very misleading because:

This style of read request is typically used for:

Metric Summary

The rest of the information in this section is only valid for this metric when it appears in either the Enterprise Manager Grid Control or the Enterprise Manager Database Control (if applicable).

The following table shows how often the metric's value is collected and compared against the default thresholds. The 'Consecutive Number of Occurrences Preceding Notification' column indicates the consecutive number of times the comparison against thresholds should hold TRUE before an alert is generated.

Target Version

Evaluation and Collection Frequency

Upload Frequency


Default Warning Threshold

Default Critical Threshold

Consecutive Number of Occurrences Preceding Notification

Alert Text


Every Minute

After Every Sample



Not Defined


%value%%% of service time is spent waiting on the 'direct path read' event.

Data Source

(DeltaDirectPathReadTime/DeltaServiceTime)*100 where:

See Idle Events

User Action

In DSS type systems, or during heavy batch periods, waits on "direct path read" are normal. However, if the waits are significant on an OLTP style system, there may be a problem.

You can:

Related Topics

About Alerts

About the Metric Detail Page

Editing Thresholds

Understanding Line Charts