| Putting multiple processes on rownum selection [message #316329] |
Thu, 24 April 2008 11:32  |
toshidas2000
Messages: 104
Registered: November 2005 |
Senior Member |
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All
I have a package in which the cursor does rows selection for processing on rownum basis. Now I want to spam couple of processes in parallel, I cannot do as the cursor does selection on rownum. They can select same rows in parallel process.
I used FOR UPDATE SKIP LOCKED in cursor, but it did not work. I am 10g R2, Please help how can I put multiple processes.
Thanks
Toshi
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| Re: Putting multiple processes on rownum selection [message #316332 is a reply to message #316329 ] |
Thu, 24 April 2008 11:38  |
Michel Cadot
Messages: 15244
Registered: March 2007
Location: Nanterre, France, http://... |
Senior Member |
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| Quote: | FOR UPDATE SKIP LOCKED
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This does not exist in 10g and below.
Or if you prefer it is a hidden featture that can only be used by Oracle.
You have problem with it, it does not surprise me. You don't know how to use it.
If you want to run 2 processes in parallel you have to know how to partition your data in 2 sets. If you don't how to do this, you can't parallel your process.
Use rowid instead of rownum if you don't have a primary key or other deterministic criteria.
Regards
Michel
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| Re: Putting multiple processes on rownum selection [message #316334 is a reply to message #316332 ] |
Thu, 24 April 2008 12:03 |
toshidas2000
Messages: 104
Registered: November 2005 |
Senior Member |
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I clearly did not understand what you said. I have a primary key, but how it affects??
I do select * from table_a
where rownum<500
It processes this 500 rows. I want to make this process faster, but when I put another process. It does the same cursor??
select * from table_a
where rownum<500
Both might select the same set of row?? How do I use rowid. Please help...
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| Re: Putting multiple processes on rownum selection [message #316339 is a reply to message #316334 ] |
Thu, 24 April 2008 12:21 |
Michel Cadot
Messages: 15244
Registered: March 2007
Location: Nanterre, France, http://... |
Senior Member |
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Don't use rownum which is a local number (local to the query).
Use a global criteria like primary key or something else in your table and if there is nothing in the data themselves to separate in partition, use rowid.
Regards
Michel
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| Re: Putting multiple processes on rownum selection [message #316375 is a reply to message #316339 ] |
Thu, 24 April 2008 18:11 |
toshidas2000
Messages: 104
Registered: November 2005 |
Senior Member |
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Can you please help me on how to use rowid??
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| Re: Putting multiple processes on rownum selection [message #316393 is a reply to message #316375 ] |
Thu, 24 April 2008 23:22 |
Michel Cadot
Messages: 15244
Registered: March 2007
Location: Nanterre, France, http://... |
Senior Member |
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First give the description of the table, give the query you have to partition, as I said: use rowid ONLY if you can't partition by a logical way, can you?
You are an expert, explain why you can't.
Regards
Michel
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