Question

I have an application that generates an H2 database.

When I execute the application on Windows XP it generates an .h2.db file with size 176K, but when I execute the same application on Unix (SunOS) it generates an .h2.db file with size 1126K, although they contain exactly the same data.

Can anyone explain what might be causing the UNIX generated file to be so much larger?

Thanks!
Martin

Answer 1

The easiest way to shrink the database file in this case is to open and close it. An alternative is to run the statement shutdown compact

In your case, the “Unix” database is not fully compacted, that means it contains empty pages in the database file (the empty pages where most likely temporarily contained the transaction log; this is normal). When closing the database, H2 will try to compact the database file by moving unused pages to the end of the file and then truncating the file. The default compact time is 0.2 seconds. Probably this 0.2 seconds were not quiet enough to fully compact the database in case of the “Unix” platform, but enough for the “Windows” platform.