On Tue, Feb 08, 2011 at 06:02:28PM +0100, Branko Čibej wrote:
> On 08.02.2011 16:34, Bert Huijben wrote:
> > An even better solution would be that SQLite tries to do things completely 
> > in memory and only *creates* a tempfile when needed. (It seems it now 
> > creates the file anyway; but doesn't use it until needed. Introducing a 
> > heavy performance penalty on NTFS, but not on extXfs)
> 
> You mentioned testing on journalled filesystems. Maybe you don't
> consider ext3 and ext4 to be journalled, but my tests were done on
> journalled HFS+ on Mac OS.
> 
> Yes, creating a temporary file is moderately expensive. But in the
> approach I showed, you really only create one temporary table and/or
> database per WC operation, not 50 zillion.
> 
> That said, I agree that a lot more testing and measuring needs to be
> done. And after all, a memory-backed temporary table is in the worst
> case backed by swap space.

All good points, yes.

Getting the queries right is much more important than worrying about
the temp_store pragma.

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