How to determine the cursor record count before the "open cursor"?

Question

Is it possible to determine the record count of an explicit cursor without running a count()? Say, my cursor definition is something like this,
CURSOR cur_vehicle
IS
SELECT os.order_id, os.order_item, vs.part_id
vs.part_num,
vs.iso_num,
vs.model_yr
vs.dealer_cde,
vs.cust_cde,
px.plant_cd
FROM parts_source vs,
orders_source os,
plant_tbl_crossref px
wHERE os.order_id = vs.order_id
AND vs.part_id = os.part_id
AND vs.plant_cde = px.plant_cde
ORDER BY os.order_id;
I want to log the count of records returned by the above cursor prior to the first fetch, without running a count(1) for the query in cursor select.
I know adding " Count(1) over(order by null) " in the cursor SELECT will bring it. But that does not help me log the record count to some log file or table before opening the cursor for processing.
To conclude, my objective is to update the record count of cursor in some table before processing

Answer 1

sarvan wrote:
Is it possible to determine the record count of an explicit cursor without running a count()?
..snipped..No. The only way to do it correctly is inside that select.
Each select is a consistent read. Which means that if this is done as 2 select statements, the 1st select can see a different version of the data than the 2nd select statement. does. So if you want a count and that to be consistent and on the same version of the data than the select, it has to be done as part of the select.
Also consider what a cursor is. It is not a result set of sorts that is created in memory upfront - with a convenient interface that tells you the size/number of rows of that result set.
A cursor is basically a program that reads database data as input and produce output. A fetch from a cursor is an instruction for this program to execute and output data.
There's no data set that is created by the cursor from which the count can be determined. The cursor program does have state variables - like +%RowCount+ that specifies how many rows the cursor has thus far output. And you need to run that cursor to the end (no more output) in order to determine the total number of rows output by the cursor.