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Oracle Forms 10g data block optimizer hint [message #681714]

Wed, 19 August 2020 02:35

Rennokas
Messages: 3
Registered: August 2020

Junior Member

Hi

How can one get optimizer hints to work in data block query.
I want the parallel hint to work.

Source type is table, alias is set and I tried /*+ PARALLEL(a,35)*/ and just PARALLEL(a,35) in the Optimizer hint part of the block.
Neither works it seems. In session sql I see that alias is added but hint is not added to the query.

Renno

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Re: Oracle Forms 10g data block optimizer hint [message #681716 is a reply to message #681714]

Wed, 19 August 2020 03:55

Michel Cadot
Messages: 68773
Registered: March 2007
Location: Saint-Maur, France, https...

Senior Member
Account Moderator

This does not answer the question but are you sure that trying to use a parallelism of 35 is wise?

[Updated on: Wed, 19 August 2020 03:55]

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Re: Oracle Forms 10g data block optimizer hint [message #681717 is a reply to message #681714]

Wed, 19 August 2020 04:01

Rennokas
Messages: 3
Registered: August 2020

Junior Member

There is max 240 parallel query servers available in db. So might be ok.

I found out that data block "Optimizer hint" not working might be oracle bug.

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Re: Oracle Forms 10g data block optimizer hint [message #681718 is a reply to message #681714]

Wed, 19 August 2020 04:04

John Watson
Messages: 8994
Registered: January 2010
Location: Global Village

Senior Member

Welcome to the forum. Please read the OraFAQ Forum Guide and How to use code tags and make your code easier to read

This doesn't answer the question either, but 35 as a DOP is not good. It is said by those who should know that the hashing algorithms used to distribute rows between parallel servers are based on powers of two, so it is important that the DOP should be a power of two also.

What if you run the statement with the hint from SQL*Plus? Does it parallelize then?

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Re: Oracle Forms 10g data block optimizer hint [message #681719 is a reply to message #681718]

Wed, 19 August 2020 04:32

Rennokas
Messages: 3
Registered: August 2020

Junior Member

John Watson wrote on Wed, 19 August 2020 04:04

Welcome to the forum. Please read the OraFAQ Forum Guide and How to use code tags and make your code easier to read

This doesn't answer the question either, but 35 as a DOP is not good. It is said by those who should know that the hashing algorithms used to distribute rows between parallel servers are based on powers of two, so it is important that the DOP should be a power of two also.

What if you run the statement with the hint from SQL*Plus? Does it parallelize then?

Okey so something like 32 sounds better ? Smile

In sql plus I it works fine. Parallel sessions appear and it is much much faster.

I have a workaround with "From clause query" instead of "Table". It is basically a procedure with select statement in varchar2 variable. I use replace to add values to parameters.
Then I do set_block_property query_data_source_name to the sql. Before execution I enable parallel query and after query I disable it.

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