> -----Original Message----- > From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On > Behalf Of S øren Lassen > Sent: Wednesday, April 29, 2009 2:01 AM > To: SAS-L@LISTSERV.UGA.EDU > Subject: Re: How to create a dataset by appending a single > (i.e same) dataset multiple times.?? > > Gerhard, > I do not suggest using "set statement with 100 input > datasets". I suggest > iterating over the same set statement a number of times. > > Why so complicated? Because the original poster wanted that order > of the obs. > > I think that Dan is right - as the size of the input data set grows, > the advantage of using a single data step decreases, and may > eventually disappear. On the other hand, I still prefer this log > entry (the times were for the original 3 obs. sample data set): > > NOTE: The data set WORK.WANT has 300 observations and 2 variables. > NOTE: DATA statement used: > real time 0.00 seconds > cpu time 0.00 seconds > > to parsing a log with 100 notes about PROC APPEND. > > But of course, if the order of the observations is not > important, your suggestion is probably to be preferred. > > Regards, > Søren > > On Wed, 29 Apr 2009 04:44:37 -0400, Gerhard Hellriegel > <gerhard.hellriegel@T-ONLINE.DE> wrote: > > >I'd not use a set statement with 100 input datasets! Note > that SAS creates > >a buffer for each dataset which costs a lot of memory and a > lot of CPU > >time. > >If you want to do that, use at least open=defer as option for each > dataset. > > > >One question: why so complicated? The following does the > same, only with > >another order for the obs: > > > >data a; > > set sashelp.class; > > do i= 1 to 100; > > output; > > end; > > drop i; > >run; > > > >Gerhard > > > > > >

Well, as usual, then L has given the OP several options to choose from. I also appreciate the various posts because I always learn something, or at least am reminded of things to think about that I sometimes fail to do. I hadn't thought about the implications of having a very wide dataset on overhead for proc append. Thanks Gerhard. And I agree with Søren that a single data step produces a much cleaner log. And data _null_ presented a novel use of Proc surveyselect. Always interesting on the L.

Dan

Daniel Nordlund Bothell, WA USA