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

Last updated on SEPTEMBER 08, 2023

Applies to:

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("<SCHEMA_NAME>"."<TABLE_NAME>");


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
********************************************************************************

Changes

Cause

My Oracle Support provides customers with access to over a million knowledge articles and a vibrant support community of peers and Oracle experts.