"Direct path read" Wait Event During LOB Access
(Doc ID 2287482.1)
Last updated on NOVEMBER 04, 2019
Applies to:
Oracle Database - Enterprise Edition - Version 10.2.0.1 and laterOracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Cloud Exadata Service - Version N/A and later
Information in this document applies to any platform.
Symptoms
- High "direct path read" wait events during LOB segment access causes slow application
-
10046 trace shows LOBREAD before the FETCH operation of the concerned cursor:
10046 trace shows the cursor number as 0 for the waits pertaining to LOB (WAIT #0).
Thus TKPROF output does not show related 'direct path read' wait event reported under the SQL statement section that has made the LOB read,rather it would be reported under 'Overall Totals' section. Also 1 block was read conventionally and the wait event was 'db file sequential read'. This is LOB Index block.
Changes
Column Data type was changed to LOBs as part of application migration.
Cause
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In this Document
| Symptoms |
| Changes |
| Cause |
| Solution |
| References |