Re: ridiculously time-consuming subqueries

I have to ask which release of Oracle are you using?  Second, does subquery factoring help any (using WITH)?  You could combine those two queries into one WITH query.

To know why these are taking so long we'll need to see plans for each of the queries (I suspect the plans will be the same).


 
David Fitzjarrell
Primary author, "Oracle Exadata Survival Guide"




On Wednesday, March 12, 2014 11:52 AM, William Threlfall <William.Threlfall_at_albertahealthservices.ca> wrote:
 
 
Hi experts,
 
I have a query in which I am trying to get the CMV and EBV results for the patient’s last transplant.
I put in the following subquery code:
 
  (SELECT RECIPIENT_CMV_IGG
    FROM PAT_TRANSPLANT PT, SDF_SEROLOGY_VERIFICATION_TO SV,
         DOCUMENTS DOCS, TX_DOCUMENTS TXD
    WHERE PT.PAT_ID        = PD.PAT_ID
    AND   PT.PAT_ID        = DOCS.PAT_ID
    AND   PT.PAT_ID        = LTV.PAT_ID
    AND   PT.TRANSPLANT_ID = TXD.TRANSPLANT_ID
    AND   PT.DATE_OF_TRANS = LTV.LAST_TRANS_DATE
    AND   DOCS.DOC_ID      = TXD.DOC_ID
    AND   DOCS.DOC_ID      = SV.DOC_ID
    AND   DOCS.DOC_KIND_ID = 10108
  ) AS CMV,
  (SELECT RECIPIENT_EBV
    FROM PAT_TRANSPLANT PT, SDF_SEROLOGY_VERIFICATION_TO SV,
         DOCUMENTS DOCS, TX_DOCUMENTS TXD
    WHERE PT.PAT_ID        = PD.PAT_ID
    AND   PT.PAT_ID        = DOCS.PAT_ID
    AND   PT.PAT_ID        = LTV.PAT_ID
    AND   PT.TRANSPLANT_ID = TXD.TRANSPLANT_ID
    AND   PT.DATE_OF_TRANS = LTV.LAST_TRANS_DATE
    AND   DOCS.DOC_ID      = TXD.DOC_ID
    AND   DOCS.DOC_ID      = SV.DOC_ID
    AND   DOCS.DOC_KIND_ID = 10108
  ) AS EBV
 
In the above code, PD = PATIENT_DEMO and LTV = LAST_TRANSPLANT_VIEW, which are in the FROM clause in the main query.
 
When I comment out these subqueries, the rest of the main query executes in less than 5 minutes, but with these subqueries in I had to stop the query because it was running for over an hour and still wasn’t finished yet.
 
Can anyonesee any obvious explanation for why these subqueries are taking so long to execute?
Can anyonesuggest a better way to get the CMV and EBV results for the last transplant?
 
I only want one CMV and one EBV result(i.e. one value for each, in one row) returned per patient. I am not certain if there are multiple 10108 documentsattached to the last
transplantfor any patients -that is possible.  In that case I want the resultto be “POSITIVE”if any of them are POSITIVE, otherwise “NEGATIVE”.
 
Thanks, - Bill.
 
 
_______________________________________
Willliam J. (Bill) Threlfall, MSc
Clinical Informatics Coordinator - OTTR
Transplant Services, University of Alberta Hospital
Alberta Health Services
Aberhart Centre, Room 9221
8440 112 Street
Edmonton, AB T6G 2B7
 
Telephone: 780-407-6175  FAX: 780-407-8981
 
Alberta Health Services
www.albertahealhservices.ca
 
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