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Re: optimize union in ase query

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Hello,

 

I shall try to provide some answers on the remarks of Simon and Jeff.

 

Compatibility mode for sure was not on, although I set it during the tests, in that particular run was off (I checked sp_show_options)

 

There was not any plan clause and also the sysqueryplans is empty, so I don't think that some existing plan was loaded.

 

It is really interesting to check what Jeff proposed, I hope to do it later today, for the moment I have not access on the system.

I mean the use of parenthesis in this

(query 1

union

query 2)

union all

(query 3

union

query 4)

 

Concerning the use of the large pool, is something I also noticed and it keeps happening in many queries in this installation. The average query in this system contains complex joins and many tables like the ones I have posted here. The biggest table in terms of number of rows is around 1 million and usually these joins involve 2-3 tables of 400000-500000 rows and some very small tables (less than 1000). I am not sure if this is an explanation.

 

alternative_greedy_search was on, I tested the query with this setting offand I think it run slightly slower.


I appreciate a lot Simon's remarks on reformatting, this case is something like an advanced workshop for me.


Thank you a lot for your help


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