Marco Manyevere wrote:
> In one test I did a couple of months back, I found that appending IDs
to the end of a dynamic array perfomed _much_ _much_ slower than a
WRITESEQ to the end of a disk file and the dynamic array wasnt even a
100 000 records long. We were able to reduce the time required to
produce a report from over 30 minutes to less than 2 minutes by removing
the dynamic array operations and replacing them with WRITESEQs. We tried
all the different syntaxes of appending to the array with no noticeable
difference in poor performance once the array got large.
Quick test on my development PC, on unidata 7.1
Source:
BIG.REC = ""
FOR ZEROS = 1 TO 10
RUN.TO = 1:STR("0",ZEROS)
BIG.REC = ""
START.TIME = SYSTEM(12)
FOR A = 1 TO RUN.TO
BIG.REC<-1> = "test string"
NEXT A
END.TIME = SYSTEM(12)
CRT RUN.TO:" iterations = ":END.TIME - START.TIME)"MR2,":" ms
":((END.TIME-START.TIME)/RUN.TO):" ms per iteration"
NEXT ZEROS
Output:
10 iterations = 1 ms 0.1 ms per iteration
100 iterations = 0 ms 0 ms per iteration
1000 iterations = 0 ms 0 ms per iteration
10000 iterations = 3 ms 0.0003 ms per iteration
100000 iterations = 34 ms 0.0003 ms per iteration
1000000 iterations = 363 ms 0.0004 ms per iteration
10000000 iterations = 3710 ms 0.0004 ms per iteration
Error when attaching shm (-1476392888, 0, 0), errno=8
The above does show that <-1> gives fast appending and that there isn't
much of a penalty as sizes increase. The only issue would be running out
of memory :-)
This seems fast to me - is it totally out of line with your tests?
Ed
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