Re: Question about Bitmap Heap Scan/BitmapAnd

On 2/13/07, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> bitmapqualorig = list_difference_ptr(bitmapqualorig, qpqual);
>
> What's not immediately clear is why the condition was in both lists to
> start with. Perhaps idx_lieu_parking is a partial index with this as
> its WHERE condition?

Yes, it is: "idx_lieu_parking" btree (parking) WHERE parking = true .
Sorry for not pointing it immediatly.
If not, the index is not used at all (there are very few lines in lieu
with parking=true).

So the basic explanation is that it's in both lists due to the partial
index and only qpqual keeps the condition? I would have expected the
opposite but it doesn't change anything I suppose?

Thanks for your answer.

--
Guillaume