In addition, what seems to be odd is that fetching the data takes most of the time from the total time. For example (snapshot from Aqua Data Studio retrieving the data from the Derby in-memory table):
Would it be considered normal to take over 2 minutes to fetch 2,357 records? Here is the same snapshot when the Left-Join was converted to the Inner-Join: ----- Forwarded by Pavel Bortnovskiy/JEFCO on 01/05/2011 12:12 PM ----- From: Pavel Bortnovskiy/JEFCO To: "Derby Discussion" <[email protected]> Date: 01/05/2011 12:04 PM Subject: Left-Join extremely slow in comparison to Inner-Join. How to tune Derby? Hello, all: I am using Derby as an in-memory DB. While executing a complex query (which contains a union and several left-joins), we discovered that this query with a left join would take about 3.5 mins to execute and fetch the data, whereas the same query with the left join replaced with the inner join would take just 30 seconds. What tools or API is available at our disposal to tune the in-memory Derby, to see its execution plan, to try to figure out why it is taking such an extraordinary time to fetch about 2,500-3000 records. I also noticed that by running the same query over and over, the time to execute and fetch seems to be slowly creeping up as well - it started with 2.5 mins, then grew to 3 mins and now it's almost 4 mins. Any help would be greatly appreciated! Regards, Pavel. Jefferies archives and monitors outgoing and incoming e-mail. The contents of this email, including any attachments, are confidential to the ordinary user of the email address to which it was addressed. If you are not the addressee of this email you may not copy, forward, disclose or otherwise use it or any part of it in any form whatsoever. This email may be produced at the request of regulators or in connection with civil litigation. Jefferies accepts no liability for any errors or omissions arising as a result of transmission. Use by other than intended recipients is prohibited. In the United Kingdom, Jefferies operates as Jefferies International Limited; registered in England: no. 1978621; registered office: Vintners Place, 68 Upper Thames Street, London EC4V 3BJ. Jefferies International Limited is authorised and regulated by the Financial Services Authority.
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