Expdp is Slow with 'DB file Sequential Read' on Table with Chained Rows (Doc ID 2033737.1)

Last updated on MAY 19, 2017

Applies to:

Oracle Database - Enterprise Edition - Version 11.2.0.1 to 12.1.0.1 [Release 11.2 to 12.1]
Information in this document applies to any platform.
***Checked for relevance on 9-Jan-2017***

Symptoms

Expdp is very slow for some tables with waits on 'db file sequential read'.

Tracing shows that majority of the waits are on statements like below:

SELECT *
FROM
RELATIONAL("TEST_TABLE_OWNER"."TEST_TABLE")


call     count       cpu    elapsed       disk      query    current        rows
------- ------  -------- ---------- ---------- ---------- ----------  ----------
Parse        1      0.01       0.00          0         43          0           0
Execute      0      0.00       0.00          0          0          0           0
Fetch        0      0.00       0.00          0          0          0           0
------- ------  -------- ---------- ---------- ---------- ----------  ----------
total        1      0.01       0.00          0         43          0           0

Misses in library cache during parse: 1
Optimizer mode: CHOOSE
Parsing user id: SYS   (recursive depth: 2)

Elapsed times include waiting on following events:
 Event waited on                             Times   Max. Wait  Total Waited
 ----------------------------------------   Waited  ----------  ------------
 db file sequential read                    995456        0.02        150.55
 direct path read                               72        0.01          0.04
 db file parallel read                           1        0.02          0.02
********************************************************************************

 

Cause

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