[Monetdb-developers] Memory use

Wouter Alink wouter.alink at gmail.com
Sat Dec 19 13:36:22 CET 2009


Hello Guido,

At the end of your COPY INTO transaction, your database will be saved
on disk, to give some guarantee that the data is on a sort of
non-volatile storage (see also
http://en.wikipedia.org/wiki/ACID#Durability). Besides storing the
data on disk, MonetDB tries to fully exploit your available (volatile)
main memory to answer your queries quickly, and tries to keep as much
of the data as possible in main memory (this is managed by MonetDB
internally).

There is one way you could trick a DBMS to use memory only: make
volatile storage to appear as non-volatile storage (for example by
creating a ram-disk).
You could also use the database in such a way that you never commit a
transaction (leave the transaction open, and roll-back at the end),
although the DBMS might still decide at some point to flush the data
to disk.

None of these tricks are recommended. For a DBMS (and I think this
holds for any proper DBMS) to function correctly, you should provide
some non-volatile storage, so that durability can be guaranteed.

Hope this answers your question,
Wouter


2009/12/18 Voornaam Achternaam <guido.middelkoop at nozhup.nl>:
>
> When I try to fill a database with the COPY INTO command, the data will
> (depending on the file used) either go:
> - Fully into Memory.
> - To HDD.
> - A combination of Memory and HDD space.
>
> Is there a way to configure MonetDB so that it always uses Memory only?
>
>
> Thanks in advance.
> --
> View this message in context: http://old.nabble.com/Memory-use-tp26843876p26843876.html
> Sent from the monetdb-developers mailing list archive at Nabble.com.
>
>
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