[R] Huge memory comsumption with foreign and RPgSQL
Peter Dalgaard BSA
p.dalgaard at biostat.ku.dk
Wed Jan 17 12:10:24 CET 2001
Perttu Muurimäki <Perttu.Muurimaki at Helsinki.Fi> writes:
> I know this is something R isn't meant to do well but I tried it anyway :)
> I have this SPSS-datafile (size 31 MB). When I converted it to a R object
> with read.spss("datafile.sav") I ended up with a .RData-file which was 229
> MB big. Is this considered normal?
Doesn't sound completely unreasonable: If all your fields fit in a
single byte to begin with and get converted to double in the process,
you'll have an inflation by a factor of 8.
> Then I tried to dump that object into a database with RPgSQL-package
> function db.write.table(object) (Memory ran out first time I tried to
> convert SPSS-file into a R-object so I was quite prepared for the
> database manouvre ; I increased the size of swap (working with linux) to
> 2500 MB) The process kept going and going and getting bigger and bigger.
> After 6 hours and 30 minutes I aborted it. At that time the process had
> grown into 1400 MB:s. Again, is this considered normal? And further more,
> am I likely to succeed if I'm patient enough?
This, however, sounds a bit excessive, although I wouldn't know
exactly what goes on inside RPgSQL... If it is converting every field
in the entire data frame to string form before sending it to the
database, then I might understand. Might it be possible to send it in
O__ ---- Peter Dalgaard Blegdamsvej 3
c/ /'_ --- Dept. of Biostatistics 2200 Cph. N
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907
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