--- Tom Lane <tgl@xxxxxxxxxxxxx> skrev: > =?iso-8859-1?q?Rolf=20=D8stvik?= > <rolfostvik@xxxxxxxx> writes: > > First i have some queries to give you a feel of > size > > of datasets and plans and times. > > You said earlier that essentially all the rows of > step_result_subset > have step_parent = 0 ... is that really true? Not true, but i am sorry if it could be intepreted that way. What i tried to say was step_result_subset contain 17 179 506 rows uut_Result_subset contain 176 555 rows There is one entry in step_result_subset with the condition step_parent = 0 for each entry in uut_result_subset (there is 176 555 rows in step_result_subset which have step_parent = 0). For this (sample) query i have found that if i select just a little bigger data set (setting start_date_time to an earlier date) the plan selected by the server does the best job and gives a more stable execution time independent of size of data sets. I also have found that my theories of the best solution has been wrong. If you (Tom) still want me to do the following steps then please tell me. > I can > hardly believe > that either 7.4 or 8.2 would use an indexscan for > Q-A if so. > > I'd be interested to see the results of > > prepare foo(int) as select id from > step_result_subset sr > where uut_result = $1 and step_parent = 0; > explain analyze execute foo(42); > > (use some representative uut_result value instead of > 42). If it doesn't > want to use an indexscan for this, disable plan > types until it does. > This would perhaps shed some light on why 8.2 > doesn't want to use a scan > like that as the inside of a nestloop. > > regards, tom lane > Best regards Rolf Østvik __________________________________________________ Bruker du Yahoo!? Lei av spam? Yahoo! Mail har den beste spambeskyttelsen http://no.mail.yahoo.com
