[EMAIL PROTECTED] wrote:
> >>
> >> --- vdbe.c~ 2005-12-19 12:42:25.000000000 -0500
> >> +++ vdbe.c 2006-10-22 16:32:45.000000000 -0400
> >> @@ -2937,7 +2937,7 @@
> >> if( pOp->p2 & OPFLAG_NCHANGE ) db->nChange++;
> >> if( pOp->p2 & OPFLAG_LASTROWID ) db->lastRowid = pNos->i;
> >> if( pOp->p2 & OPFLAG_CSCHANGE ) db->csChange++;
> >> - if( pC->nextRowidValid && pTos->i>=pC->nextRowid ){
> >> + if( pC->nextRowidValid && pNos->i>=pC->nextRowid ){
> >> pC->nextRowidValid = 0;
> >> }
> >> }
> >>
> >
>
> > The fix checked in was to remove the test altogether and unconditionally set
> > pC->nextRowidValid to 0.
>
> If, as you say, pC->nextRowidValid is always false anyway, wouldn't the
> correct fix be to not even unconditionally set pC->nextRowidValid to 0; just
> delete those two original lines entirely? It sounds like you're now
> unnecessarily setting a variable that's already false to false. (Or did I
> misunderstand your statement?)
>
I could not find a case where pC->nextRowidValid was true. But
neither did I prove it was impossible. Lets just say it was
very unlikely.
Setting pC->nextRowidValid merely invalidates a cache. Invalidating
the cache might make the code a little slower, but it will still get
the correct answer. So it is always safe to set pC->newRowidValid to
0. But we cannot leave pC->nextRowidValid in the true state because
that might leave an invalid value in the cache, resulting in a wrong
answer. So for safety, we always clear the cache here, even though
we have never seen an example where it is necessary. Better safe than
sorry.
--
D. Richard Hipp <[EMAIL PROTECTED]>
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