On Fri, Dec 01, 2006 at 08:35:24AM +0100, kamil wrote: > I want to preallocate disk space for database. I have only one table with ~1 > milion entries, each entry takes about 30 bytes. Entries are added/removed > but there is some maximum number of items, which can be put into the table > at the same time. Is it possible to allocate a fixed disk space for such > database ? How large should it be ? If yes, then is there a better way to > create large files than massive insterts/deletes ?
It's not necessarily the case that pre-allocating space does what I suspect you want. Consider a filesystem like ZFS. Writing 1GB of garbage to a file that you will eventually overwrite does not guarantee that you'll have 1GB of space to write into that file. That's because ZFS uses a copy-on-write approach and snapshots can hold references to the space that would be released on a CoW operation. And SQLite might use CoW too someday, for all I know, so that pre-creating 10^6 rows wouldn't necessarily guarantee that you have room for 10^6 UPDATEs no matter what filesystem you're using. What you want is a way to get a guarantee from the OS that there will be some amount of disk space that you can use to grow some file. You can't get that portably. Nico -- ----------------------------------------------------------------------------- To unsubscribe, send email to [EMAIL PROTECTED] -----------------------------------------------------------------------------
