Query's first run, slow...
(1) By jose isaias cabrera (jicman) on 2021-01-05 14:32:08 [link] [source]
When I run a query, most times, the first time I run it, it runs slow. But, after running the same query again, it's really fast. I know that perhaps this has been said before here, and I may have even read it, but I can't remember why. For example,
SELECT ProjID, CID, Project_Name, Start_date, Finish_Date, Target_Go_Live_Date, BL_Start,BL_Finish, Ann_CapexP, Tot_CapexP, Progress, Status, Project_Manager FROM Project_List a WHERE a.PMO_Board_Report != 'No' AND ( ( a.Target_Go_Live_Date > substr(date('now'),1,4) || '-01-15' ) OR ( a.Target_Go_Live_Date = '' AND a.Finish_Date > substr(date('now'),1,4) || '-01-15' ) ) AND a.InsertDate = ( SELECT MAX(InsertDate) FROM Project_List WHERE ProjID = a.ProjID ) group BY a.ProjID ; timer result is: Run Time: real 4.195 user 0.125000 sys 0.750000 If I run this right back, this is the timer result: Run Time: real 0.834 user 0.093750 sys 0.218750 and again, Run Time: real 0.764 user 0.140625 sys 0.156250 once more, Run Time: real 0.721 user 0.125000 sys 0.203125
Why is that again? Thanks.
(2) By Gunter Hick (gunter_hick) on 2021-01-05 14:36:44 in reply to 1 [link] [source]
This is usually due to the operating system keeping recently used disk blocks in memory and/or SQLite doing the same with recently used pages from the database file.
(3) By jose isaias cabrera (jicman) on 2021-01-05 16:06:38 in reply to 2 [source]