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Date: Wed, 24 Jun 2015 15:16:49 -0700
Message-ID: 
 <CAE1xAnsnP0e53ztmc7bwyx=Xc-Xhdf-0p07QKsHWmHumzc16zA@mail.gmail.com>
Subject: Re: Metadata names generation
From: Steven Jacobs <sjaco002@ucr.edu>
To: dev@asterixdb.incubator.apache.org
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a clear case is where there is a data type with a field named "a.b" and
another field named "a" which has a nested field named "b".

This is allowed right now. You would have to access the first as "a.b" and
the second as a.b. The quotes basically tell the parser "this is a single
name with whatever characters I want in it." To me it seems fine to
disallow some characters, but back when I had discussions about this with
Vinayak, Mike, and Till, Till was arguing against disallowing characters. I
can't really remember his reasons now though.

@Till, what are your thoughts on this?

Steven

On Wed, Jun 24, 2015 at 11:56 AM, abdullah alamoudi <bamousaa@gmail.com>
wrote:

> If that's the case, then I think we need to disallow using the "." since =
it
> is used to access nested fields and can definitely cause ambiguity.
>
> a clear case is where there is a data type with a field named "a.b" and
> another field named "a" which has a nested field named "b".
>
> Thoughts?
>
>
> On Wed, Jun 24, 2015 at 9:51 PM, Steven Jacobs <sjaco002@ucr.edu> wrote:
>
> > I think there is no completely user-friendly way around this. Basically
> our
> > names allow ALL characters if they are incapsulated in quotes, so there
> > isn't a character we can use that doesn't have the potential for
> ambiguity
> > from the user's perspective. This is why I had to change the nested stu=
ff
> > in indexing to be a list of strings rather than a single string.
> > Steven
> >
> > On Wed, Jun 24, 2015 at 11:43 AM, Chen Li <chenli@gmail.com> wrote:
> >
> > > In this case, there could be ambiguity in the names.  Does it matter?
> > >
> > > Chen
> > >
> > > On Wed, Jun 24, 2015 at 11:17 AM, Steven Jacobs <sjaco002@ucr.edu>
> > wrote:
> > >
> > > > Fieldnames do allow these characters (both of them).
> > > > Steven
> > > >
> > > > On Wed, Jun 24, 2015 at 11:15 AM, Chen Li <chenli@gmail.com> wrote:
> > > >
> > > > > I also prefer "." than "_".  Also want to confirm that field name=
s
> > > don't
> > > > > allow these two characters.
> > > > >
> > > > > Chen
> > > > >
> > > > > On Wed, Jun 24, 2015 at 10:52 AM, Steven Jacobs <sjaco002@ucr.edu=
>
> > > > wrote:
> > > > >
> > > > > > I second Young-Seek (especially since this is the syntax that
> users
> > > > will
> > > > > > use themselves for nested information in queries).
> > > > > >
> > > > > > Steven
> > > > > >
> > > > > > On Wed, Jun 24, 2015 at 10:40 AM, Young-Seok Kim <
> > kisskys@gmail.com>
> > > > > > wrote:
> > > > > >
> > > > > > > It seems better to use "." instead of "_" since "." is more
> > > intuitive
> > > > > (at
> > > > > > > least to me) than "_".
> > > > > > > For example, the FacebookUserType_address will be
> > > > > > FacebookUserType.address.
> > > > > > >
> > > > > > > Best,
> > > > > > > Young-Seok
> > > > > > >
> > > > > > > On Wed, Jun 24, 2015 at 6:31 AM, Mike Carey <dtabass@gmail.co=
m
> >
> > > > wrote:
> > > > > > >
> > > > > > > > Much cleaner!  Others should weigh in here to help finalize
> the
> > > > > > > > conventions....  Thoughts?
> > > > > > > > On Jun 23, 2015 5:31 PM, "Ildar Absalyamov" <
> > iabsa001@cs.ucr.edu
> > > >
> > > > > > wrote:
> > > > > > > >
> > > > > > > > > So the general solution is that the generated names shoul=
d
> > > become
> > > > > > less
> > > > > > > > > verbose (consider previous examples):
> > > > > > > > > 1) Anonymous fields naming scheme will change to
> > outerTypeName
> > > +
> > > > > =E2=80=9C_=E2=80=9D
> > > > > > +
> > > > > > > > > fieldName, i.e. =E2=80=9CField_address_in_FacebookUserTyp=
e=E2=80=9D is
> > changed
> > > to
> > > > > > > > > =E2=80=9CFacebookUserType_address=E2=80=9D
> > > > > > > > > 2) Anonymous collection item naming scheme stays the same=
,
> > i.e.
> > > > > > > > > =E2=80=9CField_employment_in_FacebookUserType_ItemType=E2=
=80=9D is changed
> to
> > > > > > > > > =E2=80=9CFacebookUserType_employment_ItemType=E2=80=9D (n=
ame is changed
> > because
> > > > the
> > > > > > > > > anonymous field employment naming was changed as describe=
d
> > > > earlier)
> > > > > > > > > 3) Union type completely seizes to exist in metadata (it
> > stays
> > > in
> > > > > the
> > > > > > > > > object model though), i.e.
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
> =E2=80=9CType_#1_UnionType_Field_end-date_in_Field_employment_in_Facebook=
UserType_ItemType=E2=80=9D
> > > > > > > > > is changed to
> > =E2=80=9CFacebookUserType_employment_ItemType_end-date=E2=80=9D,
> > > > > where
> > > > > > > the
> > > > > > > > > type metadata will have an additional field =E2=80=9COpti=
onal=E2=80=9D with
> > > value
> > > > > > > =E2=80=9Ctrue=E2=80=9D.
> > > > > > > > >
> > > > > > > > > > On Jun 19, 2015, at 18:11, Ildar Absalyamov <
> > > > iabsa001@cs.ucr.edu
> > > > > >
> > > > > > > > wrote:
> > > > > > > > > >
> > > > > > > > > > So I have done half of the fix, which is moved name
> > > generation
> > > > > > logic
> > > > > > > > out
> > > > > > > > > of the Metadata node to the client.
> > > > > > > > > > Up to that point nothing in Metadata format was changed=
,
> > > which
> > > > > > makes
> > > > > > > me
> > > > > > > > > wonder whether I should proceed with the following change=
s.
> > > > > > > > > >
> > > > > > > > > > As it could be seen from the previous email getting rid
> of
> > > > > > > > > union-inferred name generation would make auto generated
> type
> > > > names
> > > > > > > less
> > > > > > > > > scary, but not entirely.
> > > > > > > > > > Having in mind what Mike mentioned earlier today, shoul=
d
> we
> > > do
> > > > > > > > something
> > > > > > > > > about other auto generated type name cases?
> > > > > > > > > >
> > > > > > > > > >> On Jun 19, 2015, at 13:01, Ildar Absalyamov <
> > > > > iabsa001@cs.ucr.edu
> > > > > > > > > <mailto:iabsa001@cs.ucr.edu>> wrote:
> > > > > > > > > >>
> > > > > > > > > >> Currently we are generating the names for
> inner\anonymous
> > > > types
> > > > > in
> > > > > > > the
> > > > > > > > > following cases:
> > > > > > > > > >> 1) Anonymous field in the record.
> > > > > > > > > >> AQL Example:
> > > > > > > > > >> create type FacebookUserType as closed {
> > > > > > > > > >>         id: int32,
> > > > > > > > > >>         name: string,
> > > > > > > > > >>         address: {
> > > > > > > > > >>              address_line: string,
> > > > > > > > > >>              city: string
> > > > > > > > > >>              state: string
> > > > > > > > > >>      }
> > > > > > > > > >>     }
> > > > > > > > > >> The pattern for generating an anonymous field name is
> > > > "Field_" +
> > > > > > > > > fieldName + "_in_" + outerTypeName, which translates to
> > > > > > > > > "Field_address_in_FacebookUserType" in the given example
> > > > > > > > > >>
> > > > > > > > > >> 2) Anonymous collection (ordered\unordered list) item
> > > > > > > > > >> create type FacebookUserType as closed {
> > > > > > > > > >>         id: int32,
> > > > > > > > > >>         name: string,
> > > > > > > > > >>         employment: [{
> > > > > > > > > >>              organization-name: string,
> > > > > > > > > >>              start-date: date
> > > > > > > > > >>              end-date: date?
> > > > > > > > > >>      }]
> > > > > > > > > >>     }
> > > > > > > > > >> The pattern for generating an anonymous collection ite=
m
> > name
> > > > is
> > > > > > > > > collectionFieldName+_ItemType", which translates to
> > > > > > > > > "Field_employment_in_FacebookUserType_ItemType" in the
> given
> > > > > example
> > > > > > > > > >>
> > > > > > > > > >> 3) Nullable fields
> > > > > > > > > >> Same example as above could be used (end-date field):
> the
> > > > > pattern
> > > > > > > for
> > > > > > > > > generating a nullable field name is "Type_#" +
> > > > > > fieldsNumberInUnoinList
> > > > > > > +
> > > > > > > > > "_UnionType_" + outerTypeName, which translates to
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
> =E2=80=9CType_#1_UnionType_Field_end-date_in_Field_employment_in_Facebook=
UserType_ItemType"
> > > > > > > > > in the given example.
> > > > > > > > > >>
> > > > > > > > > >> So you can see these auto generated names could stack =
up
> > > > pretty
> > > > > > fast
> > > > > > > > > and be completely incomprehensible. Just to give you a
> small
> > > > flavor
> > > > > > of
> > > > > > > > > that, here is one of the metadata datasets type
> definitions:
> > > > > > > > > >>
> > > > > > > > > >> open {
> > > > > > > > > >>   DataverseName: STRING,
> > > > > > > > > >>   DatatypeName: STRING,
> > > > > > > > > >>   Derived: UNION(NULL, open {
> > > > > > > > > >>       Tag: STRING,
> > > > > > > > > >>       IsAnonymous: BOOLEAN,
> > > > > > > > > >>       EnumValues: UNION(NULL, [ STRING ]),
> > > > > > > > > >>       Record: UNION(NULL, open {
> > > > > > > > > >>           IsOpen: BOOLEAN,
> > > > > > > > > >>           Fields: [ open {
> > > > > > > > > >>               FieldName: STRING,
> > > > > > > > > >>               FieldType: STRING
> > > > > > > > > >>             }
> > > > > > > > > >>           ]
> > > > > > > > > >>         }
> > > > > > > > > >>       ),
> > > > > > > > > >>       Union: UNION(NULL, [ STRING ]),
> > > > > > > > > >>       UnorderedList: UNION(NULL, STRING),
> > > > > > > > > >>       OrderedList: UNION(NULL, STRING)
> > > > > > > > > >>     }
> > > > > > > > > >>   ),
> > > > > > > > > >>   Timestamp: STRING
> > > > > > > > > >> }
> > > > > > > > > >>
> > > > > > > > > >> And here are couple of fields names, generated for it =
:)
> > > > > > > > > >>
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
> Type_#1_UnionType_Field_Record_in_Type_#1_UnionType_Field_Derived_in_Data=
typeRecordType
> > > > > > > > > >>
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
> Field_UnorderedList_in_Type_#1_UnionType_Field_Derived_in_DatatypeRecordT=
ype
> > > > > > > > > >>
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
> Field_Fields_in_Type_#1_UnionType_Field_Record_in_Type_#1_UnionType_Field=
_Derived_in_DatatypeRecordType_ItemType
> > > > > > > > > >>
> > > > > > > > > >> Best regards,
> > > > > > > > > >> Ildar
> > > > > > > > > >>
> > > > > > > > > >
> > > > > > > > > > Best regards,
> > > > > > > > > > Ildar
> > > > > > > > > >
> > > > > > > > >
> > > > > > > > > Best regards,
> > > > > > > > > Ildar
> > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>
>
>
> --
> Amoudi, Abdullah.
>

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