One hour without result ?

• cowabunga

  SSC Enthusiast

  Points: 121

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  July 8, 2009 at 1:41 am

  #208021

  Hello,

  Am I wrong somewhere ?

  I have two similar databases and I just want to count records on them.

  select count(*) from database1.dbo.tablex a, database2.dbo.tablex b

  where a.aDate > '2009-01-01' or b.aDate > '2009-01-01'

  I have cancelled this request after one hour of execution without any result !!

  If I split the request in two parts with counts stored into variables, then summed, the result is nearly immediate.

  So, is my first request wrong ? Or is there an explanation about this behaviour ?

  Thanks.

  Gedeon

• SwePeso

  SSC-Dedicated

  Points: 39757

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  July 8, 2009 at 2:24 am

  #1021524

  What you did was to calculate the CARTESIAN PRODUCT.

  SELECT SUM(Items)

  FROM (

  SELECT COUNT(*) AS Items FROM TableA WHERE Col1 > '20090101' UNION ALL

  SELECT COUNT(*) AS Items FROM TableB WHERE Col1 > '20090101'

  ) AS d

  ---

  N 56°04'39.16"
  E 12°55'05.25"

• cowabunga

  SSC Enthusiast

  Points: 121

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  July 8, 2009 at 7:00 am

  #1021628

  Oops ! Stupid mistake ! :crazy:

  With millions of records in each table, sure it lasts a very long time...

  Thanks.