Re: Sequence usage patch

There was a lot of discussion about this patch, and shorter version
posted with just the CURRENT part. However, I think some felt that this
wasn't a standard yet, and therefore weren't ready to implement this.
Is that correct?

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Rod Taylor wrote:
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> Enables syntax: NEXT VALUE FOR <seqname> and CURRENT VALUE FOR <seqname>
>
> The 200N spec is based on DB2, not MSSQL, so it is very likely NEXT
> VALUE FOR will be the official syntax.
>
> http://216.239.37.100/search?q=cache:s5eWP72lHKcJ:www7b.software.ibm.com/dmdd/library/techarticle/0302fielding/0302fielding.html+%22Bobby+Fielding%22+&hl=en&lr=lang_en&ie=UTF-8
>
> DB2 uses PREVIOUS VALUE FOR <seqname> as their currval() (nothing in
> spec about this). I don't see PREVIOUS as a reserved word, but CURRENT
> certainly is -- WHERE CURRENT OF for cursors, and several other places.
>
> The attached patch makes CURRENT a reserved word. VALUE is treated as
> an IDENT to preserve the ability to use it as a column.
>
> SequenceOp is the node (primnode) used in the executor, and required
> splitting up nextval / currval into public and internal interfaces. The
> internal interface operates on the sequence OID, and the public
> interface on the sequence name as usual.
>
> Dependencies are recorded for the SequenceOp node so now we cannot drop
> a sequence used in a default expression.
>
> I've not figured out the best place to record the dependency to prevent
> the default expression from being changed for SERIAL columns yet, but
> that should be a separate patch. The concept of a serial will need to
> be brought in deeper than parser/analyze.c for this to happen.
>
> No documentation changes attached. I want to know whether this would be
> applied before I make those.
>
>
> Tom,
>
> Should I have created another parser node strictly for the gram.y stuff,
> then had it copy the info to the primnode within parse_expr.c? As it
> is, SequenceOp is left with a hanging RangeVar that is unused past that
> point.
> --
> Rod Taylor <rbt(at)rbt(dot)ca>
>
> PGP Key: http://www.rbt.ca/rbtpub.asc

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