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From Mike Carey <dtab...@gmail.com>
Subject Re: Strange Comparison Allowed
Date Wed, 19 Aug 2015 22:09:07 GMT
This all sounds somewhat wrong to me!  It's not what I remember from design
discussions of old...  I don't think we should be doing byte by byte
comparison between disparate types.  Why would users want or expect that?
Note that I'm talking about predicate cases - not internal needs like order
by or routing of data.
On Aug 19, 2015 11:47 AM, "Ildar Absalyamov" <ildar.absalyamov@gmail.com>
wrote:

> @Steven
> Index rewrite will not fire in this case, because of type mismatch. Hence
> it will fallback to non-indexed query results.
>
> 2015-08-19 11:25 GMT-07:00 Taewoo Kim <wangsaeu@gmail.com>:
>
> > @Steven: I never tried. However, it's worthwhile to check. If the query
> > semantic is correct, the optimizer will try to utilize the index
> regardless
> > of its type. My guess is, at the end, byte-by-byte comparison will occur.
> >
> > Best,
> > Taewoo
> >
> > On Wed, Aug 19, 2015 at 11:19 AM, Steven Jacobs <sjaco002@ucr.edu>
> wrote:
> >
> > > I think this is because the serialized versions of the list have their
> > > lengths among the beginning bytes, so this would make sense, since we
> > don't
> > > have a comparator for lists.
> > >
> > > @Taewoo-What about the case of an index search? Is it okay to pass the
> > > wrong type to the search (which will obviously yield unknown results)
> > >
> > > Steven
> > >
> > > On Wed, Aug 19, 2015 at 11:12 AM, Wail Alkowaileet <wael.y.k@gmail.com
> >
> > > wrote:
> > >
> > > > Actually I observed some strange behavior while comparing
> orderedLists
> > in
> > > > the order by clause.
> > > >
> > > > Input (dataset json):
> > > > { "a": 1i32, "b": [ 1, "hello" ] }
> > > > { "a": 2i32, "b": [ 1, "hello" ] }
> > > > { "a": 3i32, "b": [ 1, "hi" ] }
> > > >
> > > > Query:
> > > > for $x in dataset json
> > > > order by $x.b
> > > > return $x
> > > >
> > > > Result:
> > > > { "a": 3i32, "b": [ 1, "hi" ] }
> > > > { "a": 1i32, "b": [ 1, "hello" ] }
> > > > { "a": 2i32, "b": [ 1, "hello" ] }
> > > >
> > > > it seems the behavior is comparing by the length of the list not the
> > > values
> > > > themselves? is it expected?
> > > >
> > > > But if I do something like this:
> > > > for $x in dataset json
> > > > order by $x.b[1]
> > > > return $x
> > > >
> > > > Result:
> > > > { "a": 1i32, "b": [ 1, "hello" ] }
> > > > { "a": 2i32, "b": [ 1, "hello" ] }
> > > > { "a": 3i32, "b": [ 1, "hi" ] }
> > > >
> > > >
> > > >
> > > > On Wed, Aug 19, 2015 at 1:50 PM, Taewoo Kim <wangsaeu@gmail.com>
> > wrote:
> > > >
> > > > > Sorry. The direction of inequality operator was misleading. STRING
> 13
> > > is
> > > > > smaller than (<) POINT 20.
> > > > >
> > > > > Best,
> > > > > Taewoo
> > > > >
> > > > > On Wed, Aug 19, 2015 at 10:49 AM, Taewoo Kim <wangsaeu@gmail.com>
> > > wrote:
> > > > >
> > > > > > Yes. Type conversion (casting) only happens among numeric types
> so
> > > far.
> > > > > > Actually, since there is a type-tag, if you try to compare two
> non
> > > > > numeric
> > > > > > types, it stops the comparing as soon as it sees the first byte
> > from
> > > > both
> > > > > > side since type-tag itself has the given order (e.g., STRING
13 >
> > > POINT
> > > > > > 20). This is required for ORDER BY, too.
> > > > > >
> > > > > > Best,
> > > > > > Taewoo
> > > > > >
> > > > > > On Wed, Aug 19, 2015 at 10:45 AM, Steven Jacobs <
> sjaco002@ucr.edu>
> > > > > wrote:
> > > > > >
> > > > > >> I see, so we are technically allowed to compare anything
to
> > > anything?
> > > > > >>
> > > > > >> Steven
> > > > > >>
> > > > > >> On Wed, Aug 19, 2015 at 10:37 AM, Taewoo Kim <
> wangsaeu@gmail.com>
> > > > > wrote:
> > > > > >>
> > > > > >> > If there is no right comparator for the given types
(STRING vs
> > > > POINT),
> > > > > >> then
> > > > > >> > it does the "byte by byte" comparison.
> > > > > >> >
> > > > > >> > Best,
> > > > > >> > Taewoo
> > > > > >> >
> > > > > >> > On Wed, Aug 19, 2015 at 10:32 AM, Steven Jacobs <
> > sjaco002@ucr.edu
> > > >
> > > > > >> wrote:
> > > > > >> >
> > > > > >> > > This is currently working in master:
> > > > > >> > >
> > > > > >> > > create type CSXType as closed {
> > > > > >> > >   id: int32,
> > > > > >> > >   csxid: string
> > > > > >> > > }
> > > > > >> > > create dataset CSX(CSXType) primary key id;
> > > > > >> > >
> > > > > >> > > for $b in dataset('CSX')
> > > > > >> > > where $b.id > point("3,5")
> > > > > >> > > return $b;
> > > > > >> > >
> > > > > >> > > Is this supposed to be working?
> > > > > >> > > Steven
> > > > > >> > >
> > > > > >> >
> > > > > >>
> > > > > >
> > > > > >
> > > > >
> > > >
> > > >
> > > >
> > > > --
> > > >
> > > > *Regards,*
> > > > Wail Alkowaileet
> > > >
> > >
> >
>
>
>
> --
> Best regards,
> Ildar
>

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