DataPump Export (EXPDP) Of Partitioned Table Is Very Slow And Apparently Hangs
(Doc ID 752904.1)
Last updated on AUGUST 01, 2019
Applies to:
Oracle Database Cloud Schema Service - Version N/A and laterOracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Backup Service - Version N/A and later
Oracle Database Cloud Exadata Service - Version N/A and later
Information in this document applies to any platform.
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Symptoms
You try to export a partitioned/subpartitioned table (200 partitions, each partition with 4 subpartitions) and expdp seems to hang. You traced the expdp process and observed that for each subpartition the following statement is started:
******************************************************************************
SELECT NVL((SELECT /*+ NESTED_TABLE_GET_REFS */ 1
FROM "TEST"."PART_TAB001" SUBPARTITION ("SYS_SUBP2107") WHERE ROWNUM = 1), 0) FROM DUAL
call count cpu elapsed disk query current rows
------- ------ -------- ---------- ---------- ---------- ---------- ----------
Parse 1 0.00 0.00 0 0 0 0
Execute 1 0.00 0.00 0 0 0 0
Fetch 1 5.68 70.26 42616 42673 0 1
------- ------ -------- ---------- ---------- ---------- ---------- ----------
total 3 5.68 70.26 42616 42673 0 1
Rows Row Source Operation
------- ---------------------------------------------------
1 COUNT STOPKEY (cr=42673 pr=42616 pw=0 time=70266787 us)
1 INDEX FULL SCAN PART_TAB001_UK (cr=42673 pr=42616 pw=0 time=70266777 us)(object id 80566)
1 FAST DUAL (cr=0 pr=0 pw=0 time=3 us)
********************************************************************************
SELECT NVL((SELECT /*+ NESTED_TABLE_GET_REFS */ 1
FROM "TEST"."PART_TAB001" SUBPARTITION ("SYS_SUBP2107") WHERE ROWNUM = 1), 0) FROM DUAL
call count cpu elapsed disk query current rows
------- ------ -------- ---------- ---------- ---------- ---------- ----------
Parse 1 0.00 0.00 0 0 0 0
Execute 1 0.00 0.00 0 0 0 0
Fetch 1 5.68 70.26 42616 42673 0 1
------- ------ -------- ---------- ---------- ---------- ---------- ----------
total 3 5.68 70.26 42616 42673 0 1
Rows Row Source Operation
------- ---------------------------------------------------
1 COUNT STOPKEY (cr=42673 pr=42616 pw=0 time=70266787 us)
1 INDEX FULL SCAN PART_TAB001_UK (cr=42673 pr=42616 pw=0 time=70266777 us)(object id 80566)
1 FAST DUAL (cr=0 pr=0 pw=0 time=3 us)
********************************************************************************
If for only one partition the statement needs 70 seconds to complete, then for all 800 subpartitions you can expect 800 x 70 seconds, that means more then 15 hours.
Changes
Cause
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In this Document
| Symptoms |
| Changes |
| Cause |
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