-Re: logical plan design coming together
Timothy Chen 2012-10-12, 19:00
So is the conclusion now is to decide a new logical plan schema based on
On Fri, Oct 12, 2012 at 11:32 AM, Julian Hyde <[EMAIL PROTECTED]> wrote:
> For those implementing parsing & validation of the query language. Please
> let me share my hard-earned wisdom...
> 1. Separate parsing and validation. The parser should do the absolute
> minimum of validation. Don't try to validate identifiers. Don't do any
> type-checking. It will make errors better ('This function needs a boolean
> parameter' versus 'Expecting "true" or "false" or "<token> and" or 101
> other possibilities'.) And allows the parser to stay focused on one task
> which is difficult enough: converting text into a parse tree.
> 2. During the validation phase, do not modify the parse tree. If you need
> to annotate each node with a type, put it into a map from parse tree node
> -> type, not into a field in each node. Put any state you need (e.g. scope
> for resolving identifiers) into a temporary state that exists only during
> validation (think of the visitor pattern). And definitely do not do any
> tree-surgery. If you need to rewrite the tree, do it post validation. (In
> the planner, or just before planning, is a good time.) See
> On Oct 12, 2012, at 10:34 AM, Ted Dunning <[EMAIL PROTECTED]> wrote:
> > Great comments.
> > One particular high-level comment that Julian made is a criticism that I
> > have made in the past of other projects. It is probably good for my
> > character to be on the receiving side of this criticism for once.
> > The question is why should we use/invent a new concrete syntax when JSON
> > would do just as well (I am dropping the XML part of the suggestion due
> > known prejudices on this list).
> > I don't have a good answer to this question. It makes certain problems
> > quite a bit easier. Moreover, I have said in the past that it is nuts to
> > re-invent concrete syntax for config files and extension languages like
> > this.
> > My course going forward is that I think I will put down both syntaxes and
> > let folks form their own opinion. Using JSON will definitely move things
> > ahead more quickly since other folks have done the parser for us.
> > On Fri, Oct 12, 2012 at 12:05 AM, Julian Hyde <[EMAIL PROTECTED]>
> >> Ted,
> >> Great start. I've made some comments on the doc.
> >> Julian
> >> On Oct 11, 2012, at 10:48 PM, Ted Dunning <[EMAIL PROTECTED]>
> >>> The design for the logical plan is coming together. Anybody should be
> >> able
> >>> to get to the interim design document at
> >>> You should also be able to see the discussion so far. Many thanks to
> >>> Timothy Chen for kibitzing very well as I wrote. His astute
> >>> and questions were critical.
> >>> I have to go sleep now, but it would be great to see progress on this
> >> while
> >>> I sleep. Remember that comments and questions are as valuable (or more
> >> so)
> >>> than text. Remember also, this document has a complete history so we
> >>> reconstruct it no matter what happens.
> >>> I would particularly like eyes on this (if practical) from Camuel,
> >>> Gera and Julian Hyde. They have had some very good thoughts about this
> >>> layer in the past and probably will spot several errors in what I have
> >>> written.
> >>> The plan for this document as it stabilizes is to put it into the
> >> web-site
> >>> under the documentation area. WE will probably want to do that before
> >>> really is done to make sure that people can find it easily and to
> >> a
> >>> checkpoint is in Apache-land.
> >>> See y'all tomorrow.