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

integrity 357416268 at qq.com
Fri Jul 19 08:31:02 CEST 2013


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
> 

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| Stefan.Manegold at CWI.nl | DB Architectures   (DA) |
| www.CWI.nl/~manegold/  | Science Park 123 (L321) |
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