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Queries : SQL
Thread: Query Extents versus SQL
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Thread Status: Active Total posts in this thread: 3
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pbelanger
Newbie Joined: Feb 13, 2009 Post Count: 5 Status: Offline |
Q1: From my reading to date, it seems that all non-SQL Query options either need Extents turned on (bad for performance) or a collection from which to search, is this correct? Q2: I am assuming that Extents cause the table contents to be transferred from the DBMS to DataNucleus, is this correct? Q3: As if the query expression tree were evaluated by DataNucleus instead of the DBMS (which would be bad for performance), is this correct? Q4: I MUST be misunderstanding something because I get the impression that to get good query performance implies coding the queries in native SQL, is this correct? |
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ganzuoni
Expert Joined: Nov 16, 2005 Post Count: 1009 Status: Online |
Q1: From my reading to date, it seems that all non-SQL Query options either need Extents turned on (bad for performance) or a collection from which to search, is this correct? Q2: I am assuming that Extents cause the table contents to be transferred from the DBMS to DataNucleus, is this correct? Q3: As if the query expression tree were evaluated by DataNucleus instead of the DBMS (which would be bad for performance), is this correct? Q4: I MUST be misunderstanding something because I get the impression that to get good query performance implies coding the queries in native SQL, is this correct? Q1: why do you assume that you get bad performances. Do you have any evidence of this. Q2: No Q3: See Q1 answer Q4: it depends. Guido ---------------------------------------- Guido Anzuoni http://www.objectmagic.org |
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erik
Expert Belgium Joined: Mar 12, 2004 Post Count: 2991 Status: Offline |
Q4. datanucleus tries to push down queries to the database as much as possible ---------------------------------------- Erik Bengtson  |
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