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From Sanjay Madhavan <sanjay.madha...@gmail.com>
Subject Poi Excel 2007 and Large number of data records
Date Fri, 17 Jul 2009 13:20:42 GMT
We have been using POI  for EXCEL generation for a number of years
successfully.

Recently we started using the EXCEL2007 (OOXML) generation capabilities of
POI 3.5.
The reason we wanted the OOXML capabilities was to generate excel reports
with more than 64K records.

As soon as we started using the OOXML/POI 3.5beta5 version we started having
enormous memory issues that pretty much makes POI unusable for our
scenarios.

We regularly generate reports with 20K -50k records and this was handled
easily with the excel format.

The OOXML format with poi uses humongous amounts of memory even for modest
number of records.

For example we generated a report with 14K records and unless we allocated
1.2GB of heap space to the Java VM the report could not complete. The usual
error is the Java VM crashes with a not enough heap space error.

I would appreciate if anybody could advise us on how to avoid this memory
situation.

Also why does POI 3.5 keep everything in memory?

Are there any plans to rework POI 3.5 to better manage generation of large
excel 2007 worksheets?


Thanks and regards

/Sanjay

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