On 08-12-2021 10:13, Dmitry Yemanov wrote:
28.11.2021 14:45, Mark Rotteveel wrote:
We don't have anything like this. Theoretically, we could extend
IRecordSet with something similar (although it would also require a
protocol change), but the question is whether it's really needed.
Personally, I don't see it useful per se. If users want to know a
number of rows, then perhaps an explicit getRowCount() method would
be more useful (*). But AFAIU the Java API does not mention it.
(*) not applicable to uni-directional cursors?
The intent of the method is to report the position of the current row.
The example it is abused by some to get the total size was just an
illustration of why people would expect a value after requesting the
last row. But the same would be a problem if people went to last,
scrolled around and then want to know the current row position.
I was thinking about providing both "current position" and "row count"
information values for a cursor. Both are doable, however the former has
some issues:
[..]
3) "row count" makes it possible to know the position after fetchLast()
and everything else could be calculated locally by the client library,
thus making the server-supported "current position" totally unnecessary.
Do I miss anything? Could we agree on having only "row count" returned
via op_info_cursor and leaving "cursor position" (getRow() in Java API)
up the connectivity library developers?
Looked at it again, and being able to get the total row count will work
for me. Is this information already available, or does this still need
to be implemented?
One last thing I was wondering about (but haven't had time to verify):
what happens with positional updates or deletes when scrolling?
Specifically:
- After an update: does the cursor have the original row content or the
updated content?
- After a delete: does the row disappear from the cursor, does the
cursor retain the original content of the row, or does an 'empty' (e.g.
all NULL) row exist in the cursor?
Mark
--
Mark Rotteveel
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