[Monetdb-developers] VACUUMing MonetDB? (was: MonetDB memory management)
monetdb at quidecco.de
Fri Apr 23 09:28:52 CEST 2010
Many RDBMS pile up stale index structures to a certain extent and
therefore have a cleanup operation ("vacuuming") which should be
invoked regularly in order to maintain best performance. So it
doesn't seem unreasonable if MonetDB also piles up some data
related to already deleted rows.
As I did not find anything related in the documentation, I wonder:
1. Does this actually apply to the MonetDB design?
2. If yes, is there a defined operation to do so (other than
restarting the server, which might do the trick according to some
3. When such a cleanup operation is performed (either through an
on-line feature, or through server restart), are there any tradeoffs
to be considered, like degradation of still useful indexes?
Many thanks in advance.
original message follows:
> Does anyone has the same memory management problem as me?
> When I inserted many records like: Insert into tbl1 (id,dt)
> values(1,blob ‘…………………………………………’);
> Memory is used up to 1G.
> That's OK. But when I delete the whole table like: Delete from tbl1;
> None memory is released, still 1G is used.
> And when i insert again, memory used keeps increasing.
> Is this a problem or is it the way MonetDB works?
> Best Regards,
> Xiao Lei
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