Tom Lane wrote:
> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > Sorry, I am not understanding. If he does:
> > ...
> > here, isn't he sitting at the start of the fourth row, no?
>
> No. He is sitting *on* the third row. If he now does FETCH 1, he will
> advance to and return the fourth row; on the other hand, if he does
> FETCH -1, he will back up to and return the second row.
OK, and it makes sense FETCH -1 will move back a row rather than
re-reading the row.
> The cursor must be considered to be positioned on its current row, not
> between rows, or the SQL-defined operations UPDATE WHERE CURRENT OF and
> DELETE WHERE CURRENT OF don't make any sense. (We don't support those
> yet, but we should someday.)
Yes, that's where the positioning makes sense.
> BTW, looking at Date and the SQL spec, I now realize that the recently
> made change to convert FETCH 0 into a no-op is wrong; per spec, FETCH
> RELATIVE 0 means "re-fetch the current row, if any". By analogy, MOVE 0
> should probably return "MOVE 1" if you are on a real row, "MOVE 0" if
> you are not, corresponding to the number of rows you'd have gotten from
> FETCH 0. Ugly, but ...
OK, I will fix those. I am working on it now. I think I am going to
have to break the internal representation that a zero fetch means fetch
all. Right now, we use INT_MAX for fetch all in PerformPortalFetch.
-- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610)
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