Re: Must the file be deleted after "copy binary into table from file"?

Stefan Manegold Stefan.Manegold at cwi.nl
Fri Jul 19 08:37:58 CEST 2013


Meng,

it is IMHO very unlikely that we will add such feature.
After all, copying the files yourself before executing the binary copy into is just as "convenient", isn't it?
Another advantage of the move rather than a copy is that MonetDB does not need room for two copies of the file on the filesystem where the dbfarm is located.

Stefan

----- Original Message -----
> Thanks very much for explaining these to me, but is it possible to provide
> two options of move, one do the move and reserve, one just move? That will
> be very convenient for uses.^_^
> 
> 
> Sincerely,
> Meng
> 
> 
> PS,google mail in China is very unstable, often got disconnected from
> internet for some reason, so I have to applie another account here.
> 
> 
> 
> 
> ------------------ Original ------------------
> From:  "Stefan Manegold"<Stefan.Manegold at cwi.nl>;
> Date:  Fri, Jul 19, 2013 02:15 PM
> To:  "Communication channel for MonetDB users"<users-list at monetdb.org>;
> Cc:  "Niels Nes"<Niels.Nes at cwi.nl>; "sjoerd"<Sjoerd.Mullender at cwi.nl>;
> Subject:  Re: Must the file be deleted after "copy binary into table from
> file"?
> 
> 
> 
> Hi Meng,
> 
> for efficiently, i.e., to avoid a file copy, MonetDB's binary copy into
> simply moves(^) the user-provided and to be loaded files into its dbfarm.
> Thus, if you need to preserve a copy of the files you provide, you need to do
> so yourself before executing a binary copy into.
> 
> Best,
> Stefan
> 
> (^)
> 
> 1) The actual behavior (move) is actually different than the copy that the
> documentation at
> http://www.monetdb.org/Documentation/Cookbooks/SQLrecipes/BinaryBulkLoad
> suggests. We need to fix the latter.
> 
> 2) The actual behavior currently differs between data types; for numerical
> types, the user-provided files are moved as explained above; for stings, the
> files are read and processed, i.e., the used-provided file remains in place
> as-is. We need to consider unifying this behavior, e.g., by deleting also
> the user provided files for strings once they have been processed/loaded.
> 
> 3) In case the copy into file, e.g., due to a failing sanity check after the
> file is moved, that data is factually lost, i.e., the files are gone, but no
> data is loaded into the database; we need to either document this clearly,
> or make the implementation behave like a transaction.
> 
> 
> 
> ----- Original Message -----
> > can i have the file reserved?
> > 
> > 
> > 
> > Thanks
> > Meng
> > _______________________________________________
> > users-list mailing list
> > users-list at monetdb.org
> > http://mail.monetdb.org/mailman/listinfo/users-list
> > 
> 
> --
> | Stefan.Manegold at CWI.nl | DB Architectures   (DA) |
> | www.CWI.nl/~manegold/  | Science Park 123 (L321) |
> | +31 (0)20 592-4212     | 1098 XG Amsterdam  (NL) |
> 
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-- 
| Stefan.Manegold at CWI.nl | DB Architectures   (DA) |
| www.CWI.nl/~manegold/  | Science Park 123 (L321) |
| +31 (0)20 592-4212     | 1098 XG Amsterdam  (NL) |




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