[Csync2] recursive selects with sqlite

[Lars Ellenberg]

On Wed, Oct 22, 2008 at 05:41:03PM +0200, Art -kwaak- van Breemen wrote:
> Hi,
> 
> On Wed, Oct 22, 2008 at 04:39:05PM +0200, Lars Ellenberg wrote:
> > but: my benchmarks show that it is in fact a HUGE improvement (factor 20
> > or so in my test setup) in case it is a recursive operation on a
> > non-recursive, single filename.
> > 
> > but the union DOUBLES the time compared to the "select this or (that and something)"
> > when it _is_ a recursive operation.
> I've got some real live values ;-) :

I thought so...

can you please repeat these test, for four variations:

  > /dev/null
  export LANG=C LC_ALL=C ; > /dev/null

  | wc -l 
  export LANG=C LC_ALL=C ; | wc -l

I expect some interessting results...

> Anyway:
> asdf clearly does not exist.
> 0.big.gen.jpg is a single file
> 0 is a rather large directory, but totals less than 10% of the
> database ;-).
> 
> I've run it a few times after stopping inetd on an idle system
> with 4G memory.
> 
> I've noticed the slowdown on sqlite2, and that's the reason that
> I switched to sqlite3, which did not solve this particular
> problem, so I fixed it to union all ;-).
> 
> I can try dumping the sqlite3 database into an sqlite2 database
> just to make sure...

won't hurt to know for both sqlite3 and sqlite2.

thanks,

-- 
: Lars Ellenberg
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