Sorry about the delayed response but I¹ve 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? I¹m happy to work on getting something together as I¹ll 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] >
