Le lundi 12 juin 2006 à 08:02 -0700, Suavi Ali Demir a écrit :
> if it is a forward only cursor, when you do a select * and loop
> through all rows and doSomething() with each row (and not hold a
> reference to the data yourself), there would be only 1 row's data in
> memory at a given time, no? (or few rows if Derby prefetches in chunks
> as you do rs.next())
Cool :)
if it's right it is wonderfull.
Yes I only deals with forward only cursor and I loopthought all rows
without hold any references.
I can't use stored procedure since this is BLOB data wich contains
serialized objects.
best regards
--
yves piel
>
>
> [EMAIL PROTECTED] wrote:
> yves pielusenet writes:
>
> > Le vendredi 19 mai 2006 à 13:13 -0700, Stanley Bradbury a
> écrit :
> >> yves pielusenet wrote:
> >>
> >> >Hello,
> >> >I have such a table :
> >> >CREATE TABLE data (
> >> > numvign INTEGER PRIMARY KEY,
> >> > data BLOB NOT NULL
> >> >)
> >> >
> >> >This table should have millions of records. I have to
> iterate over all
> >> >records.
> >> >What is the best way (I don't want to have a
> outOfMemoryException) :
> >> >
> >> >for(int i=0; i>> > theData = select data from data where
> numvign=i;
> >> > doSomething(theData);
> >> >}
> >> >
> >> >or :
> >> >
> >> >alldata = select data from data order by numvign;
> >> >while(alldata.hasNext()){
> >> > doSomething(allData.next());
> >> >}
>
> Depends on what "doSomething" does. If doSomething could be
> expressed
> as SQL or done from a stored procedure, you wouldn't have to
> materialize the entire 1 mill rowset in the client.
>
> Instead of either getting all 1 mill rows into a single rs, or
> performing 1 mill queries yielding a single-row rs, you could
> try to
> read as many rows as you think is safe, and repeat until you
> are
> done. But this doesn't work so well if there are "holes" in
> your pk
> sequence...
>
> --
> dt
>
>
