investigating expdp slowness
- From: rjamya <rjamya@xxxxxxxxx>
- To: Oracle Discussion List <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 26 Oct 2011 22:09:14 -0400
ok here is the deal, 11gr2 RAC, running expdp to export few schemas,
everything works fine but one single table takes long time, it has only 7m
rows, few raw columns and a varchar2(4000). no large objects of any kind.
This one takes long time, more than 15-20 minutes. So I traced the expdp
session and found that in normal direct path mode, it only writes 64 blocks
at a time. What gives? why is this limit? can this limit be tweaked? Also
just for fun i expdp'd this table in external_table mode and it runs under 4
minutes.
here is snipped from DW trace
KUPF:21:07:05.261: ...ObjLen = 19136512
KUPF:21:07:05.261: In kupfReqBuffer...
KUPF:21:07:05.261: In kupfioReqBuffer...
KUPF:21:07:05.261: ...returning buffer with length = 262144
KUPF:21:07:05.261: ...bdx->kupfbdxLpBlkBln = 0
KUPF:21:07:05.261: In kupfWriteBuffer...
KUPF:21:07:05.261: In kupfioWriteBuffer...
KUPF:21:07:05.261: ...nBytesToWrite = 262144
KUPF:21:07:05.261: ...nBytesToWrite+kupfbdxLpBlkBln = 262144
KUPF:21:07:05.261: ...nBlocksToWrite = 64
KUPF:21:07:05.261: ...nBlocksAvail = 4294962612
KUPF:21:07:05.261: ...nBlocksThisPass = 64
KUPF:21:07:05.261: ...nBytesThisPass = 262144
KUPF:21:07:05.261: ...nBlocksToSave = 0
KUPF:21:07:05.263: ...wrote 64 blocks to dump file 1
KUPF:21:07:05.263: ...nBytesThisPass = 262144
KUPF:21:07:05.263: ...nBytesThisPass-kupfbdxLpBlkBln = 262144
KUPF:21:07:05.263: ...ObjLen = 19398656
KUPF:21:07:05.263: In kupfReqBuffer...
KUPF:21:07:05.263: In kupfioReqBuffer...
KUPF:21:07:05.263: ...returning buffer with length = 262144
KUPF:21:07:05.263: ...bdx->kupfbdxLpBlkBln = 0
KUPF:21:07:05.264: In kupfWriteBuffer...
KUPF:21:07:05.264: In kupfioWriteBuffer...
KUPF:21:07:05.264: ...nBytesToWrite = 262144
KUPF:21:07:05.264: ...nBytesToWrite+kupfbdxLpBlkBln = 262144
KUPF:21:07:05.264: ...nBlocksToWrite = 64
KUPF:21:07:05.264: ...nBlocksAvail = 4294962548
KUPF:21:07:05.264: ...nBlocksThisPass = 64
KUPF:21:07:05.264: ...nBytesThisPass = 262144
KUPF:21:07:05.264: ...nBlocksToSave = 0
KUPF:21:07:05.266: ...wrote 64 blocks to dump file 1
KUPF:21:07:05.266: ...nBytesThisPass = 262144
KUPF:21:07:05.266: ...nBytesThisPass-kupfbdxLpBlkBln = 262144
Trying to understand why direct path takes over 20 minutes wtiring 64 blocks
at a time and external_Table can dump same table in under 4.
Any ideas? many thanks in advance
-----
Best regards
Raj
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