I think you will get a quicker response on the POI Developer list. Look for the thread "Performance Question with CTSheetDataImpl.java"
About all I can say now as I am under a deadline. Dave On Jun 17, 2010, at 5:26 PM, Zoran Avtarovski wrote: > Sorry about the delayed response but I’ve been away for while. If this is > correct this is huge (no pun intended). > > We have a project in which we desperately need something like this. Are > there instructions for this? I’m happy to work on getting something together > as I’ll have to do it anyway. > > Z. > > >> >> Yes, that is the correct track. There have been improvements in the last 10 >> days. >> >> (1) Get hold of the latest night build. >> >> (2) Find the email thread titled: "Performance Question with >> CTSheetDataImpl.java" in the archives. >> >> The short version is that Bryce Alcock analyzed where bad performance >> occurred >> and then later Yegor made some targeted improvements which yield significant >> improvements for "in order" creation of XSSF files. These are very likely the >> improvements that are sought. >> >> Regards, >> Dave >> >> >> On Jun 9, 2010, at 12:28 PM, <[email protected]> >> <[email protected]> wrote: >> >>>> This was suggested by Yegor Kozlov on Dec 7, 2008: >>>> >>>> Yegor - I created an example demonstrating how to generate large workbooks >>> and avoid OutOfMemory: >>>> >>> http://svn.apache.org/repos/asf/poi/trunk/src/examples/src/org/apache/poi/xss >>> f/usermodel/examples/BigGridDemo.java >>>> >>>> If you search this list you can find his original email explaining it in >>> more detail. >>>> >>>> Justin >>>> >>>> -----Original Message----- >>>> From: K raghavendra Rao [mailto:[email protected]] >>>> Sent: Tuesday, June 08, 2010 3:06 PM >>>> To: [email protected] >>>> Subject: Re: Performance Issue with POI 3.6 as compared to 2.5.1 >>>> >>>> Nick, David, >>>> Thank you both for your response. >>>> >>>> I got held up with other work and hence couldn't respond earlier. >>>> >>>> Please clarify the following. >>>>>>>> My hunch is that you'll find HSSFWorkbook from >>>> 3.6 to be slightly faster than from 2.5, or otherwise little different.<< >>>> >>>> My understanding is that, to be able to generate .xlsx files I need to use >>> XSSFWorkbook and NOT HSSFWorkbook. Hence that rules out the possibility of >>> using HSSFWorkbook. Please correct me if I am wrong. >>>> >>>> Based on David's reply, here is what I tried. >>>> <This is the first time I am working with NIGHTLY builds. Please correct me >>> if my approach is wrong> >>>> I downloaded the poi-3.7-SNAPSHOT-20100528.jar NIGHTLY build and replaced >>> the earlier one: poi-3.6-20091214.jar >>>> >>>> So now I have 2 environments with the following settings to test the >>> PERFORMANCE between POI 3.6 and 2.5.1. >>>> >>>> Env1: >>>> POI version 3.6 with XSSFWorkbook (updated with the above mentioned NIGHTLY >>> build jar. Other 3.6 jars are the same) >>>> >>>> Env2: >>>> POI version 2.5.1 with HSSFWorkbook >>>> >>>> The report that I am generating has a SQL SELECT query which returns 65,000 >>> records in 2 seconds. Env2 provides the file in less than 10 seconds. Env1 >>> takes around 15 mins!! >>>> >>>> The BIG QUESTION for my project team is: Can POI EFFICIENTLY support >>> generation of MS Excel 2007 (.xlsx) files which have more than 66,000 >>> records? Now, I need to be able to make this decision to accordingly convey >>> to the management. We had migrated from .CSV files to POI due to the user >>> preference of native MS Excel files over CSV. >>>> >>>> If anybody has managed to achieve this, PLEASE HELP. >>>> >>>> Let me know if you need any further details. >>>> >>>> Regards, >>>> Raghu >>>> >>>> >>>> >>>> ----- Original Message ----- >>>> From: [email protected] >>>> To: [email protected] >>>> Sent: Tuesday, May 25, 2010 5:33:51 AM GMT -05:00 US/Canada Eastern >>>> Subject: Re: Performance Issue with POI 3.6 as compared to 2.5.1 >>>> >>>> On Mon, 24 May 2010, K raghavendra Rao wrote: >>>>>> I was using POI 2.5.1 to generate .xls files until the record count >>>>>> crossed the 65k+ limit set by Excel 2003. At this point, I switched to >>>>>> POI 3.6 and to XSSFWorkbook (from the previous HSSFWorkbook) >>>> >>>> This'll be the main cause. My hunch is that you'll find HSSFWorkbook from >>>> 3.6 to be slightly faster than from 2.5, or otherwise little different. >>>> >>>> XSSFWorkbook is xml based (the whole of the ooxml file format is), and >>>> processing it needs a bit more memory and cpu than the older binary >>>> format. >>>> >>>> Otherwise, see David's reply about some recent xssf performance >>>> improvements >>>> >>>> Nick >>>> >>>> --------------------------------------------------------------------- >>>> To unsubscribe, e-mail: [email protected] >>>> For additional commands, e-mail: [email protected] >>>> >>>> >>>> --------------------------------------------------------------------- >>>> To unsubscribe, e-mail: [email protected] >>>> For additional commands, e-mail: [email protected] >>>> >> >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: [email protected] >> For additional commands, e-mail: [email protected] >> > --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
